What this is
Weekly counts of nationally notifiable diseases as reported to CDC's National Notifiable Diseases Surveillance System (NNDSS). Every figure comes from CDC's published data and every row links back to the CDC record it came from.
What "provisional" means here
In CDC's own words, cases reported by state health departments "are subject to ongoing revision of information and delayed reporting", so "numbers listed in later weeks may reflect changes made to these counts as additional information becomes available." A number you read here for a past week may not be the number CDC shows for that week later. This site records those changes rather than overwriting them, and the footer shows how many revisions have been observed.
MMWR weeks
Surveillance is reported by MMWR week — a standard week numbering used across US public health reporting, which does not line up exactly with calendar months. Week 1 of an MMWR year does not necessarily start on 1 January.
A blank is not a zero
Most cells in this dataset have no number. That is normal and it does not mean zero cases. CDC publishes a flag saying why, and these are CDC's definitions, not our paraphrase:
| Flag | CDC's definition |
|---|---|
| - | No reported cases — the reporting jurisdiction did not submit any cases to CDC. |
| U | Unavailable — the jurisdiction was unable to send the data, or CDC was unable to process it. |
| N | Not reportable — the condition was not reportable by law, statute or regulation in that jurisdiction. |
| NN | Not nationally notifiable. |
| NP | Nationally notifiable but not published. |
| NC | Not calculated — insufficient data to support the calculation of this statistic. |
Only - is close to "no cases", and even it means none were submitted, not that none occurred. Treating the others as zero would claim an absence of disease the data does not support, so they are always rendered as flags, never as numbers.
Reporting jurisdictions, and why totals are easy to get wrong
CDC publishes states, the District of Columbia, New York City, US territories, census divisions and national totals in a single column. The divisions and totals are aggregates of the same cases. Adding them to a list of states double- or triple-counts every case.
Worked example, cumulative year to date at MMWR week 33 of 2026, Measles,
Indigenous: CDC's U.S. Residents figure is 2,419; states plus DC plus New
York City also sum to 2,419; and the nine census divisions separately sum to 2,419. This
site therefore labels every row with its geographic level and never mixes levels in a total.
The national chart uses CDC's own U.S. Residents row rather than any sum we
compute.
New York City reports separately from New York State, so both appear and neither contains the other.
Cumulative figures are not all over the same span
CDC's footnote: cumulative year-to-date and 52-week-maximum figures "are determined from periods of time when the condition was reportable in the jurisdiction (i.e., may be less than 52 weeks of data or incomplete YTD data)." Comparing cumulative counts between jurisdictions can therefore mislead.
Coverage
MMWR years 2022 to the present, all 138 conditions CDC publishes in this table — from anthrax and botulism through Lyme disease, measles, pertussis, tuberculosis and the arboviral and viral haemorrhagic fevers.
CDC publishes 139 labels; two of them, Coccidioidomycosis, total and Coccidioidomycosis, Total, are one condition under two spellings, so joins use a normalised key and the label is kept verbatim on every observation. Measles appears as two labels that are genuinely different things and are kept apart: Measles, Indigenous (acquired in the US) and Measles, Imported (acquired abroad).
Many conditions have no reported cases at all in these years. They are still listed, because "nothing was reported" is a result and dropping them would misstate what the surveillance system covers. Where CDC published a flag rather than a number, the flag is shown.
Earlier years exist in separate archived CDC datasets and are not included yet.
Cases in people not usually resident in the US are assigned by CDC to a separate
Non-U.S. Residents reporting area and are not part of the national figure shown
here. CDC notes that country of usual residence "is currently not reported by all
jurisdictions or for all conditions".
Source
- CDC NNDSS Weekly Data — every figure on this site.
- CDC NNDSS weekly tables
- CDC measles data and research
No news reports, no aggregators, no third-party dashboards.
Out of scope
- Any case-level or patient-level detail.
- Vaccination advice, risk scoring or clinical guidance of any kind.
- Forecasting or modelling of outbreak trajectories.
Corrections
If something here contradicts CDC, that is a bug. Write to corrections@ushealthatlas.org.
Please include the reporting jurisdiction, MMWR year and week, disease label, and the CDC URL that contradicts it. Note that NNDSS counts are provisional and revised, so a figure differing from CDC's today may simply mean this snapshot predates a revision — the fetch date is in the banner.