Vaccine Adverse Event Reporting System (VAERS)

Vaccine Adverse Event Reporting System Summary

Summary:    Established in 1990, the Vaccine Adverse Event Reporting System (VAERS) is a national early warning system to detect possible safety problems in U.S. licensed vaccines. VAERS is co-managed by the Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA). VAERS is a post-marketing safety surveillance program, collecting information about adverse events (possible side effects) that occur after the administration of U.S. licensed vaccines. This online database provides a nationwide mechanism by which VAERS reports are made available to the public and may be reviewed and analyzed. The VAERS data are updated weekly. and include reports processed through the previous Friday, effective December 18, 2020. On June 30, 2017, VAERS released a new reporting form, called the VAERS 2.0 Report Form. This new form replaced the now obsolete VAERS-1 Report Form, which was active from July 1, 1990 to June 29, 2017. Changes include: addition of new data elements, revisions to existing data elements, and elimination of some older data elements. See the Vaccine Adverse Event Reporting System (VAERS) web site for more information.

DISCLAIMER:  

VAERS accepts reports of adverse events and reactions that occur following vaccination. Healthcare providers, vaccine manufacturers, and the public can submit reports to VAERS. While very important in monitoring vaccine safety, VAERS reports alone cannot be used to determine if a vaccine caused or contributed to an adverse event or illness. The reports may contain information that is incomplete, inaccurate, coincidental, or unverifiable. Most reports to VAERS are voluntary, which means they are subject to biases. This creates specific limitations on how the data can be used scientifically. Data from VAERS reports should always be interpreted with these limitations in mind.

The strengths of VAERS are that it is national in scope and can quickly provide an early warning of a safety problem with a vaccine. As part of CDC and FDA's multi-system approach to post-licensure vaccine safety monitoring, VAERS is designed to rapidly detect unusual or unexpected patterns of adverse events, also known as "safety signals." If a safety signal is found in VAERS, further studies can be done in safety systems such as the CDC's Vaccine Safety Datalink (VSD) or the Clinical Immunization Safety Assessment (CISA) project. These systems do not have the same limitations as VAERS, and can better assess health risks and possible connections between adverse events and a vaccine.

Key considerations and limitations of VAERS data:

  • Vaccine providers are encouraged to report any clinically significant health problem following vaccination to VAERS, whether or not they believe the vaccine was the cause.
  • Reports may include incomplete, inaccurate, coincidental and unverified information.
  • The number of reports alone cannot be interpreted or used to reach conclusions about the existence, severity, frequency, or rates of problems associated with vaccines.
  • VAERS data are limited to vaccine adverse event reports received between 1990 and the most recent date for which data are available.
  • VAERS data do not represent all known safety information for a vaccine and should be interpreted in the context of other scientific information.

VAERS data available to the public include only the initial report data to VAERS. Updated data which contains data from medical records and corrections reported during follow up are used by the government for analysis. However, for numerous reasons including data consistency, these amended data are not available to the public.

VAERS staff at CDC and the FDA follow up on all serious adverse event reports to obtain additional medical, laboratory, death certificates and/or autopsy records to help understand the circumstances. However, VAERS public data do not generally change based on the information obtained during the follow-up process.

There are limitations to VAERS data. A report to VAERS does not mean that the vaccine caused the adverse event, only that the adverse event occurred some time after vaccination. Read more about interpreting VAERS data at Additional Information: Data Limitations.

Incidence:   Reports of adverse events following immunization (AEFI) submitted to the Vaccine Adverse Event Reporting System. Event characteristics include symptoms reported, vaccine type, name and manufacturer, number of days between vaccination and the adverse event, vaccination date, report date, whether the event was considered serious, how the event outcome was categorized, whether the patient recovered, and the patient's age group, sex and home state.

Population:   All persons reporting adverse event(s) after vaccination, reports received in June 1990 through last Friday. Reports are updated weekly and include reports processed through the preceding Friday.

Source:    Department of Health and Human Services (DHHS), Public Health Service (PHS), Food and Drug Administration (FDA)/ Centers for Disease Control (CDC), Vaccine Adverse Event Reporting System (VAERS).
In WONDER:    You can produce tables, maps, charts, and data extracts. Obtain frequency counts for event reports, and show the percentage of unique events. Display the Event Details reported for any single event, or the text from the Adverse Event Description, Lab Data, Current Illness, Adverse Events After Prior Vaccinations, Medications At Time Of Vaccination, and History / Allergies. Select specific event, vaccine and demographic criteria to produce cross-tabulated incidence measures. You can limit and index your data by any and all of these variables:

VAERS Data Items

    Person and Place
  1. Age
  2. Sex
  3. State / Territory
    Event Characteristics:
  4. Symptoms - classified with Medical Dictionary for Regulatory Activities (MedDRA)
  5. Event Category - describes the outcome of the event
  6. Recovered - indicates if the patient recovered
  7. Serious - indicates whether event was classified as serious
  8. Onset Interval - number of days after vaccine when symptoms occurred
  9. Days in Hospital - number of days hospitalized
  10. Vaccine Administered By - public, private, other, military, work, pharmacy, senior living, school, unknown agency
  11. Vaccine Purchased By - public, private, other, military, unknown agency
  12. Report Form Version - all, VAERS-1, VAERS 2.0
  13. VAERS ID - unique identification number for this event
  14. Mfr/Imm Proj Num - Manufacturer/Immunization Project Number, when applicable
    Vaccine Characteristics:
  15. Vaccine Products - vaccine type and name
  16. Manufacturers - makers of vaccine products
  17. Vaccine Dose - the number of vaccine doses given for a vaccine
  18. Vaccine Lot - the lot number for a vaccine product
    Text fields from the VAERS form:
  19. Adverse Event Description
  20. Lab Data
  21. Current Illness
  22. Adverse Events After Prior Vaccinations
  23. Medications At Time Of Vaccination
  24. History / Allergies
    Date Characteristics:
  25. Year and month vaccinated
  26. Year and month reported
  27. Year and month report was received
  28. Year and month of onset of adverse event
  29. Year and month of death

Please refer to the following topics:


VAERS Data Request

Output:    You can produce tables, maps, charts, and data extracts. The output includes incidence counts of event reports and the percentage of unique events. As an option, you can choose to include the Adverse Event Descriptions for each event.

Variables:    You can limit and index your data by any and all of the variables.
How?    The Request screen has sections to guide you through the making a data request as step-by-step process. However, to get your first taste of how the system works, you might want to simply press any Send button, and execute the default data request. The data results for your query appear on the Table screen. After you get your data results, try the Chart and Map screens, or export your data to a file (tab-delimited line listing) for download to your computer.

For more information, see the following:
Quick Start Guide
Step 1: Organize table layout
Step 2: Select symptoms
Step 3: Select vaccine characteristics
Step 4: Select location, age and sex
Step 5: Select other event characteristics
Step 6: Search text fields
Step 7: Select dates for when the event was reported
Step 8: Select dates for when the report was received
Step 9: Select vaccination dates
Step 10: Select dates for the onset of the adverse health event
Step 11: Select dates of death
Step 12: Other options

'By-Variables'    Select variables that serve as keys (indexes) for organizing your data. See How do I organize my data? for more information.

Note:   

  • To map your data, you must select a geographical location as a "By-Variable" for grouping your results, such as State.

Help:    Click on any button labeled "Help", located to the right hand side of the screen at the top of each section. Or click on any label, such as the Group Results By label.
Send:    Sends your data request to be processed on the CDC WONDER databases. The Send buttons are located on the bottom of the Request page, and also in the upper right corner of each section, for easy access.



Step 1. Organize table layout:

Group Results By

Select up to five variables that serve as keys for grouping your data. For example, you could select to group (summarize, stratify, index) your data by Year Vaccinated and by Serious, to compare each year's number of serious and non-serious reports.

How?   

Hints:   

  • The default measures are counts and percent of total. The total number of events that match your query criteria is also shown on the Results tab, in the messages area above the table.
  • About the optional measures:
    Check the boxes under Optional Measures in section 1 on the Request tab, if you wish to output the entries from the text fields in the VAERS report form. You must group results by VAERS ID when requesting any of the optional measures. When you do so, the counts and percentages are disabled by default. You can show the counts and percentages by using the "Quick options" menu on the Results tab.
  • About charts:
    You cannot make charts when your data has more than two By-Variables.
  • About maps:
    To make a map, you must request data with a geographic location variable, such as State, as a "By-Variable." Then click the Map tab.

The following measures are measures are available as query results:

  1. Events Reported
  2. Percentages


Events Reported

The Events Reported column shows the summary count or the frequency incidence of the selected categories in the data request. For example, when data are grouped by Symptoms, then the Events Reported column shows the number of times a specific symptom occurs in the reports included in the data request, which is not to say that this is the number of persons affected by the symptom, nor the total number of unique events. This is number of times the specific symptom is mentioned in event reports.

Notes:  

  • Events and reports are not the same. For example, a single event has one "primary" or initial report, and may also have several subsequent or follow-up reports. Since January 2011, only primary reports are included in the data.
  • Some items may have more than 1 occurrence in any single event report, such as Symptoms, Vaccine Products, Manufacturers and Event Categories. If data are grouped by any of these items, then the number in the Events Reported column may exceed the total number of unique events. If percentages are shown, then the associated percentage of total unique event reports will exceed 100% in such cases. For example, the number of Symptoms mentioned is likely to exceed the number of events reported, because many reports include more than 1 Symptom. When more than 1 Symptom occurs in a single report, then the percentage of Symptoms to unique events is more than 100%. For more information, see Multiple Mentions.


Percentages

The Percent column shows the percentage of this row's cases in comparison to the total number of unique events in your query. The number of unique events is shown in the column title.

Notes:  

  • Percentages may exceed 100% of the total number of unique events. For example, the number of Symptoms mentioned is likely to exceed the number of events reported, because many reports include more than 1 Symptom. When more than 1 Symptom occurs in a single report, then the percentage of Symptoms to unique events is more than 100%. Items that may have multiple occurrences in any single Event report include Symptoms, Vaccine Products, Manufacturers and Event Categories. When data are grouped by these items, then the summary totals and associated percentages may exceed the number of unique events. For more information, see Multiple Mentions.


Optional Measures

Check the box in Section 1 with your Mouse of Spacebar key to display the narrative text entries submitted with each event report. Group results by VAERS ID when requesting optional measures. The optional measures include these text fields:

  1. Adverse Event Description
  2. Lab Data
  3. Current Illness
  4. Adverse Events After Prior Vaccinations
  5. Medications At Time Of Vaccination
  6. History / Allergies

Hints:

  • You must group by VAERS ID when you select any optional measure.
  • When optional measures are shown, the counts and percentages are disabled by default. You can show the counts and percentages by using the "Quick options" menu on the Results tab.
  • The limit for the number of rows returned in any single results set is lower when the results include any optional text fields, due to the size of these fields. The current limit for results with optional measures is 10,000 rows. If your request exceeds the limit, you can try to narrow the criteria. For example, run separate queries for each desired year of data, or for each sex.

Title

Enter any desired description to display as a title with your results.


Step 2. Select symptoms:

Symptoms

Select specific symptoms for the query. The coding of VAERS reports requires careful interpretation. All narrative text taken from original VAERS reports are classified with Medical Dictionary for Regulatory Activities (MedDRA) concepts. Symptoms represent the medical condition(s) in the adverse event description and lab data from the VAERS Report Form.

How?  
  • Select symptoms describing adverse events. The default selection is all symptoms.
  • You can search for a matching word and view details describing the symptoms associated with a specific MedDRA code. See How do I use a Finder? for help.
    Hints:
    • Click the Search tab above the list of symptoms to search.
    • After you select an item in the list, click the Details tab above the list to see details for the selected item(s).
    • Leave box empty, or use *All*, to select all values.
  • Click the "Advanced Finder Options" link for more complex searches. The link is above the list of symptoms. The "Advanced Finder" lets you look for VAERS events with any mention of symptoms in a group, AND any mention of symptoms in another group. There is no limit to the number of items in each group. You can specify up to 5 groups. For example, you may wish to find events with any mention of fever and rash. Perform the following actions:
    1. Use the top "Move" button to put terms for fever in the top box under the "Select Records" section at the left.
    2. Use the 2nd "Move" button to put terms for rash in the 2nd box, labeled "AND any of these items."
    3. If you wish to add another group, click the "Add Another Section" button below the boxes.
  • If you happen to know a symptom code, then you may:
    1. Click the link for Advanced mode (if JavaScript is enabled).
    2. Type the code into the Selections box, one code per each line. You can also paste text into the boxes.
  • See Finder Tool help for more hints.
Notes:
  • Each event report may be assigned multiple MedDRA codes, representing the symptoms described.
  • Careful interpretation of the assigned codes is recommended. Use the Finder's Search feature to find all codes associated with your interest, by searching the text in both the label and the description.
    • For example, a report coded for "Infection Bacterial" may not also be coded for "Infection," thus a requests for all of the reports with the "Infection" code value INFECT will not include those reports only coded to the value INFECT_BACT.
    • Symptom codes are unique, yet the labels and the descriptions are not unique. Click the Details tab in the Finder to see the distinctions. For example, the following Symptom labels have two different codes:
      1. Label:  FUNNY FEELING
        1. Code:   LIGHTHEADEDNESS_[IN_CONTEXT]
          Description:   FUNNY FEELING
        2. Code:   MALAISE_[IN_CONTEXT]; Description:   FUNNY FEELING
      2. Label:  FEVER
        1. Code:  FEVER
          Description:   DRUG FEVER, FEBRILE REACTION, FEVER, FEVER NEONATAL, HEAT PRODUCTION INCREASED, HYPERPYREXIA, HYPERTHERMIA, PYREXIA, REACTION FEBRILE, TEMPERATURE, TEMPERATURE ELEVATION
        2. Code:  CONVULSIONS; Description:   FEVER
      3. Label:   HEPATIC NEOPLASIA
        1. Code:   NEOPL_LIVER
          Description:   ADENOMA LIVER, HEPATIC NEOPLASM, HEPATIC NEOPLASM BENIGN, LIVER TUMOR, NEOPLASM LIVER, TUMOR LIVER
        2. Code:   CARCINOMA_LIVER
          Description:  CARCINOMA LIVER, LIVER CARCINOMA
  • The universe of possible symptoms may change with each data update, to include new symptoms that were not previously reported. To see the universe of symptoms at a given point in time, group the data request by Symptom.
  • When the data are exported, separate columns show both the symptom label and the MedDRA code for each value.
  • Note that the Finder's Expand and Collapse buttons have no effect, because the Symptoms classification list has only 1 hierarchical level.
  • Prior to the March 2007 release on WONDER, symptoms were coded in the VAERS database utilizing the FDA's Coding Symbols for a Thesaurus of Adverse Reaction Terms (COSTART) classification system. COSTART classification was replaced by MedDRA classification for all event reports in the March 2007 release.

Step 3. Select vaccine characteristics:

Limit your data to the selected categories, if desired:

  1. Vaccine Products - vaccine type and vaccine
  2. Manufacturers - makers of vaccine products
  3. Vaccine Dose - the number of vaccine doses given for a vaccine
  4. Vaccine Lot - the manufacturer's lot number for a vaccine product


Vaccine Products

Select specific vaccine type(s) and name(s) for the query. These products are organized by Vaccine Type. Your data are limited to the selected criteria.

How?  
  • The top or first level of the hierarchy are the Vaccine Types. First select an item from the first list of Vaccine Types, then click the Expand button in the Finder to see the Vaccine Names for this type of vaccine.
  • Click the Search tab and type in a word or phrase to find matching Vaccine Types and Names.
  • If you happen to know a code for either Vaccine Type or Name, then click the Advanced mode, and simply type the code into the box, one code per each line. (Advanced mode is only available when JavaScript is enabled.)
  • See How do I use a Finder? and Finder Tool help for more hints.
Notes:
  • An event report may be associated with multiple vaccine products, because the patient may have received more than one vaccine.
  • The universe of possible vaccine products may change with each data update, to include new vaccine types and names that were not previously reported. To see the universe of vaccine products at a given point in time, group the data request by Vaccine Type and by Name.
  • Effective with the November 2012 release of reports processed through October 14, 2012, the vaccine names and codes have been revised in the data. Influenza vaccines are listed by brand name. If you wish to search for reports for by influenza season, please limit or group by Date Vaccinated.
  • When the data are exported, separate columns show both the label and the code for each value.


Manufacturers

Select vaccine product manufacturers for the query. Your data are limited to the selected criteria.

How?  
Notes:
  • An event report may be associated with multiple vaccine products and thus manufacturers, because the patient may have received more than one vaccine.
  • The universe of possible vaccine manufacturers may change with each data update, to include new manufacturers that were not previously reported. To see the universe of vaccine manufacturers at a given point in time, group the data request by manufacturer.
  • When the data are exported, separate columns show both the label and the code for each value.


Vaccine Dose

Select values for how many vaccine doses the patient received. Your data are limited to the selected criteria.

How?  
Notes:
  • An event report may include multiple vaccine products and thus multiple vaccine dose values, because the patient may have received more than one vaccine.
  • Each vaccine indicated in the event report has a dose value. Group results by Vaccine Product and by Vaccine Dose to see this association. To see the association for each event, group results by VAERS ID, Vaccine Product and Vaccine Doses.
  • When the data are exported, separate columns show both the label and the code for each value. These labels and codes are:
    Code    Label
    1 1 Dose
    2 2 Doses
    3 3 Doses
    4 4 Doses
    5 5 Doses
    6 6 Doses
    7+ 7 or more Doses
    Unk Unknown
    NA Not Applicable


Vaccine Lot

Limit your data to the specified vaccine lot number(s).

How?  
  • Type full or partial identifiers, one per line, into the box, to request data limited to events with matching Vaccine Lot Numbers.
  • Leave the box blank for all events.
  • Type "NONE" to limit data to those events without a Vaccine Lot number.

Notes:
  • An event report may be associated with multiple vaccine products and thus multiple vaccine lot numbers, because the patient may have received more than one vaccine.
  • The vaccine lot numbers are not unique. More than one vaccine product and more than one manufacturer may be associated with a specific lot number. For example, Vaccine Lot Numbers 0745B and 0758K are each associated with events that indicate both POLIO VIRUS, ORAL (ORIMUNE) made by LEDERLE LABORATORIES and VARICELLA (VARIVAX) made by MERCK & CO. INC. Vaccine Lot Numbers 0970R, 1008M and 1180H are each associated with 2 different vaccines, MEASLES + MUMPS + RUBELLA (MMR II) and MEASLES + MUMPS + RUBELLA (VIRIVAC) made by a single manufacturer, MERCK & CO. INC.
  • To see the vaccine lot numbers associated with a specific vaccine product and manufacturer, group results by lot number, manufacturer and vaccine. There are over 88,000 distinct lot numbers, so you should also limit your query criteria in some other respect, such as specifying place or time period.
  • You can also type "NONE" to limit your data to those events where no lot number was indicated.
  • Some events have specified "unknown" in the Vaccine Lot Number box. These events are shown as reported with "unknown" and not recoded to show "NONE" as the value.

Step 4. Select location, age, and sex:
  1. State / Territory
  2. Age
  3. Sex
How?

State / Territory

Select all values or any combination of values to request data limited to the selected criteria.

How?  

Notes:  

  • The "United States, Territories and Unknown" group includes all of the location values, except for "Foreign" locations. Before the December 17, 2009 data release, this group was named "United States and Territories" and the group excluded both "Unknown" and "Foreign" locations.
  • The "Foreign" group includes patients from any location other than those included in the drop down list.
  • The "Unknown" group includes patients where a state is not identified. Prior to the December 18, 2020 data release, the "Unknown" category included patients who did not report their home state.
  • The identified state is from the VAERS reporting form. As of the December 18, 2020 data release, state is reported as follows:
    • patient's home state is identified;
    • if the patient's home state is missing, then the provider's state is identified;
    • if the patient's and the provider's state are missing, then the reporter's state is identified.
  • When the data are exported, separate columns show both the label and the code for each value. These labels and codes are in VAERS-Locations.txt, a simple text file with tab-separated values that can be opened as a spreadsheet.

Age

Select all values or any combination of values to request data limited to the selected criteria.

How?  

Notes:  

  • Age group at time of vaccination is determined by subtracting the patient's birth date from the vaccination date.
  • When the data are exported, separate columns show both the label and the code for each value. These labels and codes are:
    Code    Label
    0 < 6 months
    1 6-11 months
    1-2 1-2 years
    3-5 3-5 years
    6-17 6-17 years
    18-29 18-29 years
    30-39 30-39 years
    40-49 40-49 years
    50-59 50-59 years
    60-64 60-64 years
    65+ 65+ years
    U Unknown


Sex

Select all values or any combination of values to request data limited to the selected criteria.

How?  

Notes:  

  • When the data are exported, separate columns show both the label and the code for each value. These labels and codes are:
    Code    Label
    F Female
    M Male
    U Unknown


Step 5. Select other event characteristics:
Limit your data results to the selected query criteria:
  1. Event Category - describes the outcome of the event
  2. Recovered - indicates if the patient recovered
  3. Serious - indicates whether event was classified as serious
  4. Vaccine Administered By - public, private, other, military, work, pharmacy, senior living, school, unknown agency
  5. Onset Interval - number of days after vaccine when symptoms occurred
  6. Days in Hospital - number of days hospitalized
  7. Form Version - indicates VAERS Reporting Form version
  8. Vaccine Purchased By - public, private, other, military, unknown agency
  9. VAERS ID - unique identification number for this event. Leave this box empty, if you don't wish to limit your query to specific VAERS IDs.
  10. Mfr/Imm Proj Num - Manufacturer/Immunization Project Number, when applicable. Leave this box empty, if you don't wish to limit your query to specific project numbers.
How?
  • See How do I select items from the list box? for help using the list boxes.
  • Only Primary Reports are shown (not additional or follow-up reports for the same event).
  • To request data only for specific events, type full or partial VAERS IDs, one per line, into the VAERS ID box. You can send a request grouped by VAERS ID in order to see the unique event identification numbers.

Event Category

Select all values, or any combination of values, to request data limited to the selected criteria.

How?  
Notes:  
  • The outcome of the event is categorized into one or more of the following options: death, life threatening, permanent disability, congenital anomaly or birth defect, hospitalized, existing hospitalization prolonged, emergency room / office visit, emergency room, office visit, and none of the above. Note that the following three categories were added June 30, 2017: emergency room (only), office visit (only), congenital anomaly or birth defect.
  • When the data are grouped by Event Category, the number of categories mentioned in the Events Reported column is likely to exceed the number of unique events, because a single event may fall into more than category. For example, a single report may mention an emergency room visit and a life threatening reaction as outcomes.
  • When the data are grouped by Event Category, and if the total number of Events Reported exceeds the total number of unique event reports, the percentages shown will exceed 100%. The percentages are based on the total number of unique events.
  • When the data are exported, separate columns show both the label and the code for each value. These labels and codes are:
    Code    Label
    DTH Death
    LT Life Threatening
    DBL Permanent Disability
    BD Congenital Anomaly or Birth Defect*
    H Hospitalized
    HP Hospitalized, Prolonged
    ER/OF Emergency Room / Office Visit**
    ER Emergency Room*
    OF Office Visit*
    NONE None of the above
    * These values are from VAERS 2.0 Report Form,
    active June 30, 2017 to present.
    ** These values are from VAERS-1 Report Form,
    active July 1, 1990 to June 29, 2017.


Recovered

Select all values or any combination of values, to request data limited to the selected criteria.

How?  
Notes:  
  • Recovery status indicates whether the patient has recovered, not recovered, recovery is unknown, or the recovery information is missing from the report form.
  • This field is from box 20 on the current VAERS 2.0 Report Form. Box 20 is labeled: "has the patient recovered from the adverse event(s)?" For data obtained from the VAERS-1 Report Form, this field is from box 9, labeled: "Patient Recovered."
  • When the data are exported, separate columns show both the label and the code for each value. These labels and codes are:
    Code    Label
    N No
    Y Yes
    U Unknown
    M Missing


Serious

Select all values or any combination of values to request data limited to the selected criteria.

How?  
Notes:  
  • Events are classified as serious when any of the following outcomes are associated with the event:   Death, Permanent Disability, Life Threatening, Hospitalized, Existing Hospitalization Prolonged, Congenital Anomaly or Birth Defect. Prior to June 30, 2017, events were classified as serious when any of the following outcomes were associated with the event:   Death, Permanent Disability, Life Threatening reaction, or Hospitalization. Note that Congenital Anomaly or Birth Defect was added June 30, 2017.
  • When the data are exported, separate columns show both the label and the code for each value. These labels and codes are:
    Code    Label
    SER Serious
    NSER Not Serious


Administered By

Select all values or any combination of values to request data limited to the selected criteria.

How?  
Notes:  
  • The following four categories were added June 30,2017: work, pharmacy, senior living, school.
  • For events submitted using the VAERS 2.0 Report Form, military value is captured using Box 28.
  • When the data are exported, separate columns show both the label and the code for each value. These labels and codes are:
    Code    Label
    PUB Public
    PVT Private
    OTH Other
    WRK Work
    PHM Pharmacy
    SEN Senior Living
    SCH School
    UN Unknown


Onset Interval

Select all values or any combination of values, to request data limited to the selected criteria.

How?  
Notes:  
  • When the data are exported, separate columns show both the label and the code for each value. These labels and codes are:
    Code    Label
    0 0 days
    1 1 day
    2 2 days
    3 3 days
    4 4 days
    5 5 days
    6 6 days
    7 7 days
    8 8 days
    9 9 days
    10-14 10-14 days
    15-30 15-30 days
    31-60 31-60 days
    61-120 61-120 days
    121+ Over 120 days
    U Unknown


Days in Hospital

Select all values or any combination of values, to request data limited to the selected criteria.

How?  
Notes:  
  • When the data are exported, separate columns show both the label and the code for each value. These labels and codes are:
    Code    Label
    0 0 days
    1 1 day
    2 2 days
    3 3 days
    4 4 days
    5 5 days
    6 6 days
    7 7 days
    8 8 days
    9 9 days
    10-14 10-14 days
    15-30 15-30 days
    31-60 31-60 days
    61-120 61-120 days
    121+ Over 120 days
    U Unknown


Report Form Version

Select all values or any combination of values, to request data limited to the selected criteria.

How?  
Notes:  
  • The VAERS 2.0 Report Form became active June 30, 2017.
  • Before June 30, 2017, VAERS events reports were submitted using the VAERS-1 Report Form.
  • When the data are exported, separate columns show both the label and the code for each value. These labels and codes are:
    Code    Label
    1 VAERS-1
    2 VAERS 2.0


Purchased By

Select all values or any combination of values, to request data limited to the selected criteria.

How?  
Notes:  
  • For events submitted using the VAERS 2.0 Report Form, the "Purchased By" information is no longer collected.
  • For data obtained from the VAERS-1 Report Form, this category is from box 16.
  • When the data are exported, separate columns show both the label and the code for each value. These labels and codes are:
    Code    Label
    PUB Public
    PVT Private
    MIL Military
    OTH Other
    UN Unknown
    NA Not Applicable


VAERS ID

Request data for specific event identification numbers.

How?  
  • Type full or partial VAERS IDs, one per line, into the VAERS ID box, to request data limited to matching events.
  • Leave the box blank, to request data for all events.
Notes:  
  • Each event has a unique identification number, the VAERS ID.
  • If you don't know the VAERS ID for a report, you can send a request grouped by VAERS ID in order to see the list unique event identification numbers.


Manufacturer/Immunization Project Number

Request data for events that match the specified Manufacturer/Immunization Project Number(s).

How?  
  • Type full or partial identifiers, one per line, into the box, to request data limited to events with matching Manufacturer/Immunization Project Numbers.
  • Leave the box blank for all events.
  • Type "NONE" to limit data to those events without a Manufacturer/Immunization Project Number.
Notes:  
  • This field is also known as "splttype."
  • Some specific Manufacturer/Immunization Project Numbers are associated with more than one event, more than one vaccine, or with more than one manufacturer.
  • There are over 150,000 distinct identifiers, so you should also limit your query in some respect, such as selecting only a specific place or time period.
  • Some events have specified "unk" in this field to indicate an unknown value. These events are shown as reported and not recoded to show "NONE" as the value.
  • Many events do not indicate a Manufacturer/Immunization Project Number.


Step 6. Search text fields:
Limit your output by searching for words or phrases in any of these text fields:
  1. Adverse Event Description
  2. Lab Data
  3. Current Illness
  4. Adverse Events After Prior Vaccinations
  5. Medications At Time Of Vaccination
  6. History / Allergies
Hints:
  • Enter one or more words per line to find events with all words found in line. For example, if you type egg allergy, then your results show only records where both the egg and allergy were mentioned in the field.
  • Entries on more than one line will find events with any word or entire phrase found on each line. For example, if allergy is typed on the first line and sensitivity is typed on the second line, then your results show records that mention allergy OR sensitivity.
  • The default search is non-exact and finds events with other forms of the search term such as plurals. For example, if you type pregnancy, the search also looks for pregnancies. Or you can type geese and find mentions of goose.
  • Exact word searches can be performed by enclosing entire entry on single line in double quotes. For example, type "fetal loss" to look for that exact phrase only.
  • Use an asterisk (*) suffix after a word fragment to find events with this exact fragment at the beginning of the word. For example, type miscar* to find mentions of miscarry, miscarried, miscarriage, and miscarriages.
Other hints:
  • To see the text fields that match your search criteria, be sure to go up to Section 1 on the Request tab, group results by VAERS ID and also check the box to request the desired optional measure.
  • To find the search term matches to your optional measure(s) in the results, use your web browser's search function to highlight the desired text. For example, open the web browsers "Edit" menu, then click the "Find on This Page" option in the menu. An entry field labeled "Find:" appears above your web page. Type the word you wish to see highlighted into this box.
Notes:
  • See VAERS 2.0 Report Form for the instructions provided for completing the current form.
  • The contents of these text fields are from the initial VAERS reports. The text appears as submitted, removing any personal identifying information.

Adverse Event Description
This field is box 18 on the current VAERS 2.0 Report Form. Box 18 is labeled: "Describe the adverse event(s), treatment, and outcome(s), if any: (symptoms, signs, time course, etc.)." For data obtained from the VAERS-1 Report Form, this field is from box 7, labeled "Describe adverse event(s) (symptoms, signs, time course) and treatment, if any."

Current Illness (at time of vaccination)
This field is box 11 on the current VAERS 2.0 Report Form. Box 11 is labeled:  "Other illnesses at the time of vaccination and up to one month prior." For data obtained from the VAERS-1 Report Form, this field is from box 18, labeled:  "Illness at time of vaccination (specify)."

Lab Data
This field is box 19 on the current VAERS 2.0 Report Form. Box 19 is labeled:  "Medical tests and laboratory results related to the adverse event(s): (include dates). " For data obtained from the VAERS-1 Report Form, this field is from box 12, labeled:  "Relevant diagnostic tests/laboratory data."

Adverse Events After Prior Vaccinations
This field is box 23 on the current VAERS 2.0 Report Form. Box 23 is labeled:  "Has the patient ever had an adverse event following any previous vaccine?: (If yes, describe adverse event, patient age at vaccination, vaccination dates, vaccine type, and brand name)." For data obtained from the VAERS-1 Report Form, this field is from box 21, labeled:  "Adverse event following prior vaccination (check all applicable, specify)." Please note the current Report Form only focuses on the patient, while the previous Report Form focused on the patient and siblings.

Medications At Time Of Vaccination
This field is box 9 on the current VAERS 2.0 Report Form. Box 9 is labeled:  "Prescriptions, over-the-counter medications, dietary supplements, or herbal remedies being taken at the time of vaccination." For data obtained from the VAERS-1 Report Form, this field is from box 17, labeled:  "Other medications."

History / Allergies
This field combines information from boxes 12 and 10 on the current VAERS 2.0 Report Form. Box 12 is labeled: "Chronic or long-standing health conditions;" and box 10 is labeled: "Allergies to medications, food, or other products." For data obtained from the VAERS-1 Report Form, this field is from box 19, labeled:  "Pre-existing physician-diagnosed allergies, birth defects, medical conditions (specify)."

Steps 7-11: Selecting Dates
Select specific years or year/month dates to limit your request to the selected time periods. Choose between these two controls:
  1. The Date Range control is selected at first by default, with the full time period of available data shown in the range controls. Use this control to select a continuous span of time, such as May 25, 2010 - September 25, 2010.
  2. The Aggregate Date Finder lets you select specific, discrete year/month dates, such as January 2003. Any number of distinct, separate dates may be selected.
How?
  • Click a round button to switch between Date Range, Individual Date Fields or Aggregate Dates.
  • Hints for the Date Range fields:
    • Click the down-arrow to the right of each field to open the drop-down list, then click on your selection in the list.
    • Click the blue counter-clockwise swoop image to the right of the date range fields to reset the entries to the default values (all).
  • Hints for the Individual Date Fields:
    • To select more than one value in the list, press down the Ctrl key on your keyboard while you click your left Mouse button.
    • To select a range of continuous values, press down the Shift key on your keyboard while you click and drag your left Mouse button.
  • Hints for the Aggregate Date Finder:
    • The default for the Aggregate Date Finder is all values.
    • The Advanced mode let you easily pick several items from different parts of the list. Items are not selected until you click the "Move" button in Advanced mode. You may also enter values by hand, one code per line, in the Advanced mode. The code format is YYYY/MM/DD. For example, 2003/09 is September 2003.
    • The "plus" symbol, "+" indicates that you can open the item, to see more items below it.
    • The results to a search are shown in blue, and indicated by ">".
    • See How do I use a Finder? for more information on using the Aggregate Date Finder.
    • See Finder Tool help for more hints.
Notes:  
  • The Individual Date Fields for vaccination, onset and death dates combine all dates prior to 1980 into a group labeled "Before 1980." The Individual Date Field for report completed date has a group labeled "Before 1990" because the VAERS program began in 1990.
  • The universe of possible vaccination, onset and report dates may change with each data update, to include new dates that were not previously reported. To see all possible values for vaccination dates at a given point in time, group the data request by Month Vaccinated.
  • When the data are exported, separate columns show both the label and the code for each value.

Step 7. Select dates for when the report was completed:

Select dates for when the report was completed. Select specific years or year/month dates to limit your request to the selected time periods for when the report was completed. See Selecting Dates for more information using the controls.


Step 8. Select dates for when the report was received:

Select dates for when the report was received. See Selecting Dates for more information using the controls.


Step 9. Select vaccination dates:

Select dates for when the vaccination was given. See Selecting Dates for more information using the controls.


Step 10. Select dates for the onset of the adverse health event:

Select specific years or year/month dates to limit your request to the selected time periods for when the onset of the adverse health event occurred. See Selecting Dates for more information using the controls.


Step 11. Select dates of death:

Select specific years or year/month dates to limit your request to the selected time periods for when the death occurred. See Selecting Dates for more information using the controls.



Step 12. Other options:
Export Results:    If checked, then query results are exported to a local file. More information on how to import this file into other applications can be found here.
Show Totals:    If checked totals and sub-totals will appear in the results table.
Show Zero Values:    If checked rows containing zero values will appear in the results table. If unchecked, zero value rows are not displayed.
Precision:    Select the precision for the percentage calculations. When the measure calculated for a small numerator (number of items mentioned in reports) is zero, you may increase the precision to reveal the value by showing more numbers to the right of the decimal point.
Data Access Timeout:    Select the data access timeout value. This value specifies the maximum time to wait for the data access for a query to complete. If the data access takes too long to complete, a message will be displayed and you can increase the timeout or simplify your request. If you can't complete a request using the maximum timeout, contact user support and we will try to run a custom data request for you.

Data Source Information

Established in 1990, the Vaccine Adverse Event Reporting System (VAERS) is a national early warning system to detect possible safety problems in U.S. licensed vaccines. VAERS is co-managed by the Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA). VAERS is a post-marketing safety surveillance program, collecting information about adverse events (possible side effects) that occur after the administration of U.S. licensed vaccines. This online database provides a nationwide mechanism by which these reports may be analyzed and made available to the public. The data are updated weekly and include reports processed through the previous Friday.

To learn more about the methods and source of these data please refer to:


Additional Information

Suggested Data Source Citation:    United States Department of Health and Human Services, Department of Health and Human Services (DHHS), Public Health Service (PHS), Food and Drug Administration (FDA) / Centers for Disease Control (CDC), Vaccine Adverse Event Reporting System (VAERS) 1990 - last Friday, CDC WONDER Online Database.
Contact:    Please visit http://vaers.hhs.gov, or call VAERS toll-free 1-800-822-7967 or e-mail info@vaers.org.
Notes:    Review the following information:

Data Limitations:

Review the limitations and interpret VAERS data with caution:
  • The data are unverified reports of health events, both minor and serious, that occur after vaccination.
  • VAERS data are from a passive surveillance system. Such data are subject to limitations of under-reporting, reporting bias, and lack of incidence rates in unvaccinated comparison groups.
  • Reports show the simultaneous administration of multiple vaccines (making it difficult to know to which of the vaccines, if any, the event might be attributed).
  • VAERS occasionally receives case reports from U.S. manufacturers that were reported to their foreign subsidiaries. Under FDA regulations, if a manufacturer is notified of a foreign case report that describes an event that is both serious and unexpected (in other words, it does not appear in the product labeling), they are required to submit it to VAERS. These case reports are of variable data quality and completeness, due to the differences in country reporting practices.
  • In some media reports and on some web sites on the Internet, VAERS reports are presented as verified cases of vaccine deaths and injuries. Statements such as these misrepresent the nature of VAERS.
  • Establishing causal relationships between vaccines and adverse events requires additional scientific investigation. The CDC and FDA take into account the complex factors mentioned above, and others, when monitoring vaccine safety and analyzing VAERS reports.
  • VAERS staff at CDC and FDA follow up on all serious adverse event reports to obtain additional medical, laboratory, death certificates, and/or autopsy records to help understand the circumstances. However, VAERS public data do not generally change based on the information obtained during the follow-up process.
  • VAERS data available to the public include only the initial report data to VAERS. Updated data which contains data from medical records and corrections reported during follow up are used by the government for analysis. However, for numerous reasons including data consistency, these amended data are not available to the public.
  • See also the Disclaimer at Summary above.

There are limitations to VAERS data. A report to VAERS does not mean that the vaccine caused the adverse event, only that the adverse event occurred some time after vaccination. Read more about interpreting VAERS data at Additional Information above.


Multiple Mentions:

Some items may have more than 1 occurrence in any single event report, such as Symptoms, Vaccine Products, Manufacturers and Event Category. If data are grouped by any of these items, the number in the Events Reported column may exceed the total number of unique events. If percentages are shown, the associated percentage of total unique event reports will exceed 100% in such cases. For example, the number of Symptoms mentioned is likely to exceed the number of events reported, because many reports include more than 1 Symptom. When more than 1 Symptom occurs in a single report, the percentage of Symptoms to unique events is more than 100%.


Reporting Issues:

VAERS reports are included for data processed through the previous Friday, based on the date received by VAERS. VAERS data in WONDER are updated weekly. The data included in WONDER represent a "snap shot" of the VAERS records for reports received through the preceding Friday at a given point in time. For example, a report form is filled out on February 27th, for an event that occurred in January. VAERS receives the report on March 3rd. Due to processing time for data entry and verification, the report is entered into the electronic records on March 6th. Follow-up reports are entered into the record on March 16th. The initial report is captured in the WONDER system's "snap shot" for the next data update. However, follow-up reports do not appear in the WONDER system. The VAERS system receives continuous updates including revisions and new reports for preceding time periods. Duplicate event reports and / or reports determined to be false are removed from VAERS.


VAERS Event Details Report:

How to see all data for a single report?
The report feature allows you to search for details on any specific VAERS report by the VAERS ID number. There are 3 ways to get a report showing all of the data for a single event report.
  1. Select the "VAERS Report Details" button on the About page, which moves you to the "Report" tab and shows the "Event Details Report" page.
  2. Click the "Report" tab to move to the "Event Details Report" page.
  3. Send a data request from the "Request Form" tab and group results by VAERS ID. Each VAERS ID in the Results is a link to the Event Details report for that event.
Hints:
  • From the "Report" tab and the "Event Details Report" page:
    1. Type a VAERS ID into the "VAERS ID" box.
    2. Then click the "Event Details" button to get an event details report for the matching VAERS ID.
  • After a report is displayed:
    • Look below the report to find the "Event Details Report" form and request another report.
    • If you have a Results table grouped by VAERS ID, then click the "Results" tab to return to the list of VAERS IDs after you have displayed a specific report.
  • A VAERS ID consists of seven numbers followed by -1, such as 1234567-1. You may omit the '-1' from IDs entered here. for example, 1234567. Please note that some VAERS IDs start with 0, such as 0012345-1.
  • Each report shows the values for all of the fields available in CDC WONDER. See the list of variables for more information on any specific field.




This page last reviewed: Friday, July 02, 2021
This information is provided as technical reference material. Please contact us at cwus@cdc.gov.