TABLE 6. Annual reported cases of notifiable diseases and rates, by race*,†, United States, excluding U.S. Territories and Non-U.S. Residents, 2021 column labels in same order that data fields appears in each record below: Disease American Indian or
Alaska Native, No. American Indian or
Alaska Native, Rate Asian or Pacific
Islander, No. Asian or Pacific
Islander, Rate Black, No. Black, Rate White, No. White, Rate Other or Multi-Race, No. § Race not stated, No. Total tab delimited data: Anthrax — — — — — — — — — — — Arboviral diseases, Chikungunya virus disease — — 6 0.03 4 0.01 8 0.00 3 14 35 Arboviral diseases, Eastern equine encephalitis virus disease, Neuroinvasive S S S S S S S S S S 5 Arboviral diseases, Eastern equine encephalitis virus disease, Non-neuroinvasive — — — — — — — — — — — Arboviral diseases, Jamestown Canyon virus disease, Neuroinvasive S S S S S S S S S S 21 Arboviral diseases, Jamestown Canyon virus disease, Non-neuroinvasive S S S S S S S S S S 11 Arboviral diseases, La Crosse virus disease, Neuroinvasive 1 0.02 1 0.00 — — 33 0.01 — 4 39 Arboviral diseases, La Crosse virus disease, Non-neuroinvasive S S S S S S S S S S 1 Arboviral diseases, Powassan virus disease, Neuroinvasive S S S S S S S S S S 24 Arboviral diseases, Powassan virus disease, Non-neuroinvasive S S S S S S S S S S 1 Arboviral diseases, St. Louis encephalitis virus disease, Neuroinvasive S S S S S S S S S S 11 Arboviral diseases, St. Louis encephalitis virus disease, Non-neuroinvasive S S S S S S S S S S 6 Arboviral diseases, West Nile virus disease, Neuroinvasive 11 0.22 17 0.08 75 0.16 1,645 0.65 83 176 2,007 Arboviral diseases, West Nile virus disease, Non-neuroinvasive 3 0.06 8 0.04 4 0.01 631 0.25 36 217 899 Arboviral diseases, Western equine encephalitis virus disease, Neuroinvasive — — — — — — — — — — — Arboviral diseases, Western equine encephalitis virus disease, Non-neuroinvasive — — — — — — — — — — — Babesiosis, Total 6 0.16 76 0.39 53 0.13 1,749 0.79 107 683 2,674 Babesiosis, Confirmed 5 0.13 68 0.35 52 0.13 1,577 0.71 99 628 2,429 Babesiosis, Probable 1 0.03 8 0.04 1 0.00 172 0.08 8 55 245 Botulism, Total 4 0.08 12 0.05 19 0.04 147 0.06 27 27 236 Botulism, Foodborne S S S S S S S S S S 20 Botulism, Infant 1 1.21 10 3.79 14 2.09 108 3.97 17 21 171 Botulism, Other (wound & unspecified) — — 2 0.01 3 0.01 29 0.01 9 2 45 Brucellosis — — 9 0.04 14 0.03 46 0.02 21 24 114 Campylobacteriosis 631 12.88 1,869 8.34 3,173 6.73 40,554 15.90 6,747 10,435 63,409 Candida auris, clinical ** 5 0.13 21 0.14 239 0.61 234 0.11 55 54 608 Carbapenemase-producing carbapenem-resistant Enterobacteriaceae 30 0.64 74 0.34 468 1.13 1,013 0.44 203 540 2,328 Chancroid S S S S S S S S S S 3 Chlamydia trachomatis infection 17,423 358.88 23,648 107.68 448,041 990.85 470,848 187.29 129,552 524,328 1,613,840 Cholera S S S S S S S S S S 5 Coccidioidomycosis 316 12.29 631 5.92 857 5.33 7,604 6.85 4,317 6,476 20,201 Coronavirus Disease 2019 (COVID-19), Total 339,951 6,938.50 1,051,703 4,692.23 4,200,445 8,902.79 18,529,588 7,266.80 3,846,354 8,128,453 36,096,494 Coronavirus Disease 2019 (COVID-19), Confirmed 283,744 5,791.30 911,747 4,067.80 3,452,348 7,317.20 14,504,676 5,688.34 3,213,179 6,710,574 29,076,268 Coronavirus Disease 2019 (COVID-19), Probable †† 56,207 1,147.20 139,956 624.42 748,097 1,585.58 4,024,912 1,578.46 633,175 1,417,879 7,020,226 Cryptosporidiosis, Total 63 1.29 144 0.64 675 1.43 6,500 2.55 596 1,177 9,155 Cryptosporidiosis, Confirmed 48 0.98 112 0.50 554 1.17 5,006 1.96 500 971 7,191 Cryptosporidiosis, Probable 15 0.31 32 0.14 121 0.26 1,494 0.59 96 206 1,964 Cyclosporiasis 7 0.16 40 0.19 110 0.25 1,726 0.73 137 404 2,424 Dengue virus infections, Dengue §§ 3 0.06 40 0.18 8 0.02 60 0.02 37 34 182 Dengue virus infections, Dengue-like illness §§ S S S S S S S S S S 7 Dengue virus infections, Severe dengue §§ S S S S S S S S S S 4 Diphtheria — — — — — — — — — — — Ehrlichiosis and Anaplasmosis, Anaplasma phagocytophilum infection 28 0.64 61 0.29 31 0.07 4,897 1.99 129 1,583 6,729 Ehrlichiosis and Anaplasmosis, Ehrlichia chaffeensis infection 5 0.11 10 0.05 41 0.09 1,045 0.43 46 190 1,337 Ehrlichiosis and Anaplasmosis, Ehrlichia ewingii infection S S S S S S S S S S 19 Ehrlichiosis and Anaplasmosis, Undetermined ehrlichiosis/anaplasmosis 2 0.05 2 0.01 1 0.00 58 0.02 1 13 77 Giardiasis 53 1.40 278 1.45 711 1.97 6,355 3.12 1,461 2,785 11,643 Gonorrhea 9,939 204.72 9,125 41.55 270,308 597.79 199,894 79.51 50,222 160,097 699,585 Haemophilus influenzae, invasive disease, All ages, all serotypes 53 1.08 35 0.16 478 1.01 1,989 0.78 125 362 3,042 Haemophilus influenzae, invasive disease, Age <5 years, Serotype b 1 0.24 — — 2 0.06 19 0.14 2 3 27 Haemophilus influenzae, invasive disease, Age <5 years, Non-b serotype 10 2.41 3 0.21 19 0.56 85 0.60 7 13 137 Haemophilus influenzae, invasive disease, Age <5 years, Nontypeable 2 0.48 — — 17 0.50 47 0.33 8 20 94 Haemophilus influenzae, invasive disease, Age <5 years, Unknown serotype 6 0.12 1 0.00 27 0.06 109 0.04 6 23 172 Hansen's disease — — 11 0.05 1 0.00 29 0.01 3 13 57 Hantavirus infection, non-hantavirus pulmonary syndrome ¶¶ S S S S S S S S S S 2 Hantavirus pulmonary syndrome S S S S S S S S S S 14 Hemolytic uremic syndrome post-diarrheal 4 0.08 14 0.07 12 0.03 228 0.09 22 22 302 Hepatitis, Viral Disease, Hepatitis A *** 29 0.59 88 0.39 604 1.28 4,321 1.69 219 465 5,726 Hepatitis, Viral Disease, Hepatitis B, Acute *** 14 0.29 50 0.22 372 0.80 1,358 0.54 111 139 2,044 Hepatitis, Viral Disease, Hepatitis B, Perinatal infection *** S S S S S S S S S S 17 Hepatitis, Viral Disease, Hepatitis C, Acute *** 68 1.57 82 0.37 653 1.41 4,186 1.69 404 635 6,028 Confirmed 61 1.41 74 0.34 587 1.27 3,406 1.38 344 551 5,023 Probable 7 0.16 8 0.04 66 0.14 780 0.32 60 84 1,005 Hepatitis, Viral Disease, Hepatitis C, Perinatal infection *** — — 2 0.27 10 0.56 137 1.89 19 32 200 Human immunodeficiency virus diagnoses 198 4.04 705 3.15 12,865 27.27 8,114 3.18 9,387 — 31,269 Influenza-associated pediatric mortality S S S S S S S S S S 6 Invasive pneumococcal disease, All ages ††† 356 11.64 149 1.15 2,000 5.15 7,432 3.89 523 1,638 12,098 Invasive pneumococcal disease, All ages, Confirmed ††† 352 11.51 146 1.12 1,956 5.04 7,285 3.81 515 1,578 11,832 Invasive pneumococcal disease, All ages, Probable ††† 4 0.13 3 0.02 44 0.11 147 0.08 8 60 266 Invasive pneumococcal disease, Age <5 years ††† 7 0.19 15 0.11 185 0.45 401 0.19 37 125 770 Invasive pneumococcal disease, Age <5 years, Confirmed ††† 7 2.27 14 1.54 179 5.97 381 3.37 37 121 739 Invasive pneumococcal disease, Age <5 years, Probable ††† — — 1 0.11 6 0.20 20 0.18 — 4 31 Legionellosis §§§ 28 0.57 117 0.52 1,808 3.83 5,378 2.11 493 618 8,442 Leptospirosis 1 0.02 8 0.04 3 0.01 29 0.01 11 17 69 Listeriosis, Total ¶¶¶ 9 0.18 70 0.31 101 0.21 608 0.24 66 123 977 Listeriosis, Confirmed ¶¶¶ 9 0.18 67 0.30 97 0.21 587 0.23 63 118 941 Listeriosis, Probable ¶¶¶ — — 3 0.01 4 0.01 21 0.01 3 5 36 Lyme disease, Total 97 1.98 241 1.12 247 0.52 15,653 6.15 418 7,954 24,610 Lyme disease, Confirmed 54 1.10 143 0.67 154 0.33 10,261 4.03 276 5,323 16,211 Lyme disease, Probable 43 0.88 98 0.46 93 0.20 5,392 2.12 142 2,631 8,399 Malaria 1 0.02 48 0.21 1,050 2.23 99 0.04 123 182 1,503 Measles, Total **** — — 25 0.11 — — 11 0.00 1 11 48 Measles, Indigenous **** — — 18 0.08 — — 7 0.00 — 4 29 Measles, Imported **** — — 7 0.03 — — 4 0.00 1 7 19 Meningococcal disease, All serogroups 3 0.06 6 0.03 42 0.09 115 0.05 18 24 208 Meningococcal disease, Serogroups ACWY 1 0.02 3 0.01 16 0.03 40 0.02 11 12 83 Meningococcal disease, Serogroup B 1 0.02 2 0.01 2 0.00 24 0.01 3 — 32 Meningococcal disease, Other serogroups 1 0.02 1 0.00 2 0.00 7 0.00 1 4 16 Meningococcal disease, Unknown serogroup — — — — 22 0.05 44 0.02 3 8 77 Mumps 1 0.02 11 0.05 10 0.02 95 0.04 13 59 189 Novel Influenza A virus infections S S S S S S S S S S 16 Pertussis 7 0.14 46 0.21 122 0.26 1,337 0.52 99 505 2,116 Plague †††† S S S S S S S S S S 4 Poliomyelitis, paralytic — — — — — — — — — — — Poliovirus infection, nonparalytic — — — — — — — — — — — Psittacosis S S S S S S S S S S 4 Q fever, Total 3 0.06 2 0.01 12 0.03 127 0.05 19 29 192 Q fever, Acute 3 0.06 2 0.01 11 0.02 106 0.04 18 25 165 Q fever, Chronic — — — — 1 0.00 21 0.01 1 4 27 Rabies, Human S S S S S S S S S S 5 Rubella S S S S S S S S S S 7 Rubella, congenital syndrome — — — — — — — — — — — Salmonella Paratyphi infection §§§§ 1 0.02 29 0.13 2 0.00 16 0.01 9 7 64 Salmonella Typhi infection ¶¶¶¶ 1 0.02 86 0.38 16 0.03 62 0.02 43 26 234 Salmonellosis (excluding S. Typhi infection and S. Paratyphi infection) ***** 381 7.78 1,545 6.89 4,422 9.37 31,338 12.29 4,344 7,219 49,249 Severe acute respiratory syndrome-associated coronavirus disease — — — — — — — — — — — Shiga toxin-producing Escherichia coli (STEC) 91 1.86 365 1.63 762 1.62 9,499 3.73 1,505 1,721 13,943 Shigellosis 95 1.94 311 1.39 1,565 3.32 5,259 2.06 1,433 1,336 9,999 Smallpox — — — — — — — — — — — Spotted fever rickettsiosis, Total 19 0.40 9 0.04 44 0.09 965 0.38 31 189 1,257 Spotted fever rickettsiosis, Confirmed — — — — 1 0.00 38 0.01 1 3 43 Spotted fever rickettsiosis, Probable 19 0.40 9 0.04 43 0.09 927 0.36 30 186 1,214 Streptococcal toxic shock syndrome — — 1 0.01 20 0.06 108 0.07 6 10 145 Syphilis, Total, all stages ††††† 3,552 73.16 3,725 16.96 56,026 123.90 77,493 30.83 17,182 16,389 174,367 Syphilis, Congenital §§§§§ 112 268.26 39 13.89 886 139.61 1,412 50.60 162 209 2,820 Syphilis, Primary and secondary 1,213 24.99 1,181 5.38 17,153 37.93 24,433 9.72 4,656 4,398 53,034 Tetanus — — — — 5 0.01 20 0.01 1 2 28 Toxic shock syndrome (other than Streptococcal) S S S S S S S S S S 15 Trichinellosis S S S S S S S S S S 2 Tuberculosis 109 2.22 2,852 12.72 1,481 3.14 3,101 1.22 221 118 7,882 Tularemia 15 0.31 2 0.01 4 0.01 116 0.05 8 17 162 Vancomycin-intermediate Staphylococcus aureus — — 1 0.01 14 0.03 43 0.02 3 12 73 Vancomycin-resistant Staphylococcus aureus ¶¶¶¶¶ S S S S S S S S S S 5 Varicella morbidity 29 0.73 147 0.74 243 0.58 2,073 0.95 207 797 3,496 Varicella mortality U U U U U U U U U U U Vibriosis, Total 15 0.31 128 0.57 251 0.53 1,846 0.74 199 414 2,853 Vibriosis, Confirmed 8 0.17 72 0.32 116 0.25 1,019 0.41 112 229 1,556 Vibriosis, Probable 7 0.14 56 0.25 135 0.29 827 0.33 87 185 1,297 Viral hemorrhagic fevers, Crimean-Congo hemorrhagic fever virus — — — — — — — — — — — Viral hemorrhagic fevers, Ebola virus — — — — — — — — — — — Viral hemorrhagic fevers, Guanarito virus — — — — — — — — — — — Viral hemorrhagic fevers, Junin virus — — — — — — — — — — — Viral hemorrhagic fevers, Lassa virus — — — — — — — — — — — Viral hemorrhagic fevers, Lujo virus — — — — — — — — — — — Viral hemorrhagic fevers, Machupo virus — — — — — — — — — — — Viral hemorrhagic fevers, Marburg virus — — — — — — — — — — — Viral hemorrhagic fevers, Sabia virus — — — — — — — — — — — Yellow fever S S S S S S S S S S 1 Zika virus, Zika virus disease, congenital ****** S S S S S S S S S S 1 Zika virus, Zika virus disease, non-congenital S S S S S S S S S S 2 Zika virus, Zika virus infection, congenital ****** — — — — — — — — — — — Zika virus, Zika virus infection, non-congenital — — — — — — — — — — — —: No reported cases - The reporting jurisdiction did not submit any cases to CDC. U: Unavailable - The data are unavailable. S: Suppressed * Conditions with <25 cases reported in the year were not broken down by race. † Race data were collected using current Office of Management and Budget (OMB) standards for race/ethnicity data and were mapped to bridged race categories. § Any variation of disease incidence by race or ethnicity does not reflect biological differences but reflects systemic, cultural, behavioral, and social factors including structural racism. ¶ Includes individuals reported as other race or multiple races. ** Candida auris colonization/screening cases are not included in this table. These data are available on the Mycotic Diseases Branch's Tracking Candida auris page (https://www.cdc.gov/fungal/candida-auris/tracking-c-auris.html) †† Of the reporting areas that submitted 2021 aggregate COVID-19 data to CDC, two did not submit probable cases. New York (excluding New York City) and U.S. Virgin Islands did not collect probable cases. §§ Counts include confirmed and probable dengue cases. ¶¶ Case counts may include Old World hantavirus infections, such as Seoul virus. *** Chronic hepatitis B and chronic hepatitis C data are not included in NNDSS tables but reported case counts are included in the annual Viral Hepatitis Surveillance Report, 2021, published online by CDC's Division of Viral Hepatitis, available at https://www.cdc.gov/hepatitis/statistics/SurveillanceRpts.htm. ††† Counts include drug resistant and susceptible cases of Invasive Pneumococcal Disease. This condition was previously named Streptococcus pneumoniae invasive disease and cases were reported to CDC using different event codes to specify whether the cases were drug resistant or in a defined age group, such as <5 years. §§§ Beginning in 2020, the CSTE case definition changed such that cases diagnosed by PCR were classified as confirmed, whereas previously those cases were classified as suspect and did not meet the publication/print criteria. ¶¶¶ Before 2019, probable cases were not reported, and cases in neonates ≤60 days of age were counted as one case in a mother-infant pair. Beginning in 2019, confirmed and probable cases are being reported, and maternal and neonatal cases are being counted separately. **** Measles is considered imported if the disease was acquired outside of the United States and is considered indigenous if the disease was acquired anywhere within the United States or it is not known where the disease was acquired. †††† Beginning in 2020, confirmed and probable plague cases began to be combined and published. §§§§ Beginning in January 2019, cases began to be reported as Salmonella Paratyphi infection. In 2018, cases were reported as paratyphoid fever. Prior to 2018, cases of paratyphoid fever were considered salmonellosis. ¶¶¶¶ Beginning in January 2019, cases began to be reported as Salmonella Typhi infection. In previous years, cases were reported as typhoid fever. ***** Beginning in January 2019, cases began to be reported as salmonellosis (excluding Salmonella Typhi infection and Salmonella Paratyphi infection). In 2018, cases were reported as salmonellosis (excluding paratyphoid fever and typhoid fever). Prior to 2018, cases of paratyphoid fever were considered salmonellosis. ††††† Includes the following categories: primary; secondary; early non-primary non-secondary (includes cases previously reported as early latent); unknown duration or late (includes cases previously reported as late latent syphilis and cases previously reported as late syphilis with clinical manifestations) and congenital syphilis. §§§§§ Congenital syphilis cases are usually assigned to the mother's state of residence at the time of delivery. Data for congenital syphilis are aggregated by the infant's year of birth. ¶¶¶¶¶ Vancomycin-resistant Staphylococcus aureus cases reported in this table may not have been verified by CDC. CDC verified 2 vancomycin-resistant Staphylococcus aureus cases in 2021. ****** Data reported to ArboNET using the national surveillance case definition for congenital Zika virus infection (CSTE Position Statement 16-ID-01). Notes: These are annual cases of selected infectious national notifiable diseases from the National Notifiable Diseases Surveillance System (NNDSS). NNDSS data reported by the 50 states, New York City, the District of Columbia, and the U.S. territories are collated and published. Cases are reported by state health departments to CDC weekly. Because source datasets may be updated as additional information is received, statistics in publications based on that source data may differ from what is presented in these tables. Source datasets for the 2021 annual tables were officially closed on March 29, 2023. The list of national notifiable Infectious diseases and conditions for 2021 and their national surveillance case definitions are available by navigating to the https://ndc.services.cdc.gov/, Surveillance Case Definitions | CDC web page, selecting "2021" for the notifiable condition list year, checking "Infectious" conditions, and clicking "Get Notifiable List by Year". CSTE adopted the first coronavirus disease 2019 (COVID-19) national surveillance case definition on April 5, 2020, and they approved a revision to the COVID-19 national surveillance case definition, effective August 5, 2020. On June 17, 2021, a revision to the COVID-19 national surveillance case definition was approved, effective September 1, 2021. Publication criteria for the finalized 2021 data are available at https://wonder.cdc.gov/nndss/documents/2021_NNDSS_Publication_Criteria_06072023.pdf, https://wonder.cdc.gov/nndss/documents/2021_NNDSS_Publication_Criteria_03162022.pdf. See also https://www.cdc.gov/nndss/data-statistics/readers-guides/index.html, Guide to Interpreting Provisional and Finalized NNDSS Data. Population estimates for incidence rates are July 1st, 2020, estimates obtained from the National Center for Health Statistics (NCHS) postcensal estimates of the resident population of the United States for April 1, 2010, to July 1, 2020, by year, county, single year of age (range: 0 to 85 years), bridged-race (white, black or African American, American Indian or Alaska Native, Asian, or Pacific Islander), Hispanic ethnicity (not Hispanic or Latino, Hispanic or Latino), and sex (Vintage 2020), prepared under a collaborative arrangement with the U.S. Census Bureau. Population estimates for states released September 22, 2021, are available at https://www.cdc.gov/nchs/nvss/bridged_race/data_documentation.htm, https://www.cdc.gov/nchs/nvss/bridged_race/data_documentation.htm. Population estimates for territories are the 2020 mid-year estimates from the U.S. Census Bureau International Data Base, accessed on March 15, 2022, at https://www.census.gov/data-tools/demo/idb/#/country?YR_ANIM=2022, https://www.census.gov/data-tools/demo/idb/#/country?YR_ANIM=2022. The choice of population denominators for incidence is based on the availability of population data at the time of publication preparation. Annual tables for 2016 and later years are available on https://wonder.cdc.gov/nndss/nndss_annual_tables_menu.asp, CDC WONDER. Annual summary reports from 1993–2015 are available as published in the https://www.cdc.gov/mmwr/mmwr_nd/index.html, Morbidity and Mortality Weekly Report. NNDSS annual tables since 1952 are available at https://stacks.cdc.gov/nndss, CDC Stacks (once in CDC Stacks, select "Annual Reports" in the "Genre" box to the left). For most conditions, national incidence rates are calculated as the number of reported cases for each infectious disease or condition divided by the U.S. resident population for the specified demographic population or the total U.S. resident population, multiplied by 100,000. When a national notifiable infectious condition is associated with a specific age restriction, the same restriction was applied to the population in the denominator of the incidence rate calculation. In addition, population data from reporting jurisdictions in which the disease or condition was not reportable or not available were excluded from the denominator of the incidence rate calculations. Age restrictions in the numerator and denominator are applied for the following childhood conditions: Zika virus disease, congenital (age restriction in numerator and denominator is <1 year) Zika virus infection, congenital (age restriction in numerator and denominator is <1 year) Haemophilus influenzae, invasive disease <5 years (age restriction in numerator and denominator is <5 years) Invasive pneumococcal disease <5 years (age restriction in numerator and denominator is <5 years) Influenza associated pediatric mortality (age restriction in numerator and denominator is <18 years) Infant botulism (age restriction in numerator and denominator is <1 year) Congenital rubella syndrome (age restriction in numerator and denominator is <1 year) Perinatal hepatitis B infection (age restriction in numerator and denominator is ≤24 months) Perinatal hepatitis C infection (age restriction in numerator and denominator is ≤36 months). Data for congenital syphilis are aggregated by the infant's year of birth. The rate for congenital syphilis is based upon the number of reported cases per 100,000 live births, using natality data for 2021 (National Center for Health Statistics https://wonder.cdc.gov/natality.html, Natality 2021, as compiled from data provided by the Vital Statistics Cooperative Program). Congenital syphilis cases are usually assigned to the mother's state of residence at the time of delivery. The mother's race and ethnicity are used for race- and ethnicity-specific rates of congenital syphilis cases. Surveillance data reported by other CDC programs might vary from data reported in these tables because of differences in 1) the date used to aggregate the data, 2) the timing of reports, 3) the source of the data, 4) surveillance case definitions, and 5) policies regarding case jurisdiction (i.e., which jurisdiction should submit the case notification to CDC). Disease data presented in the 2021 tables reflect impacts of the COVID-19 pandemic, such as changes in exposure-related behavior, healthcare-seeking behavior, disease reporting, and public health investigations. Suggested Citation: Centers for Disease Control and Prevention. National Notifiable Diseases Surveillance System, 2021 Annual Tables of Infectious Disease Data. Atlanta, GA. CDC Office of Public Health Data, Surveillance, and Technology, 2024. Available at: https://www.cdc.gov/nndss/data-statistics/infectious-tables/index.html, https://www.cdc.gov/nndss/data-statistics/infectious-tables/index.html. Acknowledgment: CDC acknowledges the local, state, and territorial health departments that collected the data from a range of case ascertainment sources (e.g., healthcare providers, hospitals, laboratories) and reported these data to CDC's National Notifiable Diseases Surveillance System. https://www.cdc.gov/nndss/, National Notifiable Diseases Surveillance System Provided by https://wonder.cdc.gov, CDC WONDER