North America 21 Sep 2026 · Dr Natalya Mathur
ENCLAI ID ENCLAI-2026-0000420-4 · Cite

Varicella in the US: 1,011 cases in 90 days, 321 in the last 30

ENCLAI SURVEILLANCE BRIEFING · 21 SEPTEMBER 2026Varicella in the US: 1,011 cases in 90days, 321 in the last 30Varicella · The US · reported cases321reported cases in the 30 days to 21 September▲ 23% more than the 30 days before (262)262The 30 daysbefore254Same 30 days, ayear earlier1,01190 days to 21September3,6572026 so farThree 30-day windows254A year earlier26230 days before321Last 30 daysLargest counts, last 90 daysAustralia5,466South Korea5,082The US1,011Germany484Bulgaria346Hungary26111 countries with a reported count in this windowWhat this briefing shows1Reported cases rose from 262 to 321 between the two latest 30-daywindows, 23% more.2The latest count of 321 is above the 254 reported in the same 30days a year earlier.3The US accounts for 2.7% of the varicella cases reported to ENCLAIworldwide in 2026 and ranks 6 of 16 reporting countries.Read with care: reports to official surveillance, not people and not a rate. A change between30-day windows can come from reporting timing as much as from transmission.Source: official surveillance reports compiled by ENCLAI · data as of 2026-09-21 ·enclai.net/newsVerify every figure against the source data before use; ENCLAI does not guarantee accuracy orcompleteness.
  1. Reported cases rose from 262 to 321 between the two latest 30-day windows, 23% more.
  2. The latest count of 321 is above the 254 reported in the same 30 days a year earlier.
  3. The US accounts for 2.7% of the varicella cases reported to ENCLAI worldwide in 2026 and ranks 6 of 16 reporting countries.
Customise it in Visual Studio
Largest included reported counts (6 of 11 countries) · 2026-06-23 through 2026-09-21 · source-record dates; coverage varies
Australia5,466
South Korea5,082
United States1,011
Germany484
Bulgaria346
Hungary261
Varicella — United States · reported surveillance count · 2026-06-23 through 2026-09-21 · inclusive source-record dates
Varicella — United States · reported surveillance count · 2026-08-22 through 2026-09-21 · inclusive source-record dates
Varicella — United States · reported surveillance count · 2026-07-22 through 2026-08-21 · inclusive source-record dates
Varicella — United States · reported surveillance count · 2025-08-22 through 2025-09-21 · inclusive source-record dates
Varicella · combined reported surveillance count · 2026-06-23 through 2026-09-21 · inclusive source-record dates
Varicella · weekly reported-count series · Weeks starting 2026-06-15 through 2026-08-31
Largest included reported counts (6 of 11 countries) · 2026-06-23 through 2026-09-21 · source-record dates; coverage varies

The full briefing

Full 2026 picture: Varicella in United States — reported cases by year, monthly records and every briefing for this pair.

The US reported 1,011 varicella cases in the 90 days to 21 September. 321 of them came in the 30 days to 21 September, against 262 in the 30 days before. The same 30 days a year earlier had 254.

Why it matters

The US accounts for 2.7% of the varicella cases reported to ENCLAI worldwide so far in 2026. It ranks 6 of 16 reporting countries. 2025 closed at 4,326 cases, 129% above the three-year baseline of 1,886 a year. 2026 so far stands at 3,657.

The numbers

PeriodReported cases
Last 30 days (to 21 September)321
The 30 days before that262
Same 30 days a year earlier254
90 days to 21 September1,011
2026 so far (ENCLAI export)3,657
Three-year baseline (a year)1,886
The card shows varicella in the US. It compares the last 30 days with the 30 days before, as reported to ENCLAI.
The card shows varicella in the US. It compares the last 30 days with the 30 days before, as reported to ENCLAI.

What the source says

These figures come from official surveillance reports. They count reports, not people. They are not an incidence rate, the rate of new cases in a population. They do not cover the whole population. The reporting periods do not match these dates exactly. Some reports are incomplete or still in progress. Some run past the window. Some reports do not say which date they use: symptom onset, notification, or confirmation.

Caveats

  • A change between two 30-day windows can come from reporting timing as much as from transmission. The source does not say which.

Where to learn more

Varicella in the US: the 2026 picture · Varicella worldwide · the US: all diseases · How to read these counts

Retained reporting context

Included reporting countries

Varicella

12,896

combined reported surveillance count

2026-06-23 through 2026-09-21 · inclusive source-record dates

For Varicella, the combined reported surveillance count across the 11 countries with positive reported counts in this selection is 12,896. The selection uses source-record dates 2026-06-23 through 2026-09-21, inclusive. This covers only these reporting countries; source periods and completeness vary.

Exact included country membership
CountryReported countSource-record dates
Australia5,4662026-06-23 through 2026-09-21
Bulgaria3462026-06-23 through 2026-09-21
Germany4842026-06-23 through 2026-09-21
Finland802026-06-23 through 2026-09-21
Guam22026-06-23 through 2026-09-21
Hong Kong1362026-06-23 through 2026-09-21
Hungary2612026-06-23 through 2026-09-21
South Korea5,0822026-06-23 through 2026-09-21
Puerto Rico172026-06-23 through 2026-09-21
Singapore112026-06-23 through 2026-09-21
United States1,0112026-06-23 through 2026-09-21

Snapshot 2026-09-21

Weekly reporting history

Varicella

weekly reported-count series

Weeks starting 2026-06-15 through 2026-08-31

A retained retrospective weekly reported-count series across included reporting countries. Country membership and reporting completeness can vary by week. Missing weeks remain gaps. This is a separate report-series measure; it does not establish exact incidence or laboratory confirmation. Exact country membership could not be reconciled to the current primary snapshot.

Retained weekly report series
WeekReported count
2026-06-15 through 2026-06-2117711
2026-06-22 through 2026-06-2813897
2026-06-29 through 2026-07-0514196
2026-07-06 through 2026-07-1211171
2026-07-13 through 2026-07-198462
2026-07-20 through 2026-07-267303
2026-07-27 through 2026-08-025370
2026-08-03 through 2026-08-093997
2026-08-10 through 2026-08-164140
2026-08-17 through 2026-08-232450
2026-08-24 through 2026-08-302413
2026-08-31 through 2026-09-061431

Snapshot 2026-09-20

Sources and limitations

  • Window. Each quantity keeps its recorded source-selection dates and coverage notes. Dated batches and weekly or genomic observations retain their separate measures. Publication or capture dates do not establish case onset, equal cohorts or period completeness.
  • Denominator. The retained counts do not establish complete populations, equal reporting cohorts or incidence rates. Source period bounds and definitions can differ.
  • Case definition. Case definitions are set nationally and change over time. Counts for the same disease in different countries may not be counting the same thing.
  • Revisions. Agencies restate figures. Values here are as reported at the time of publication; see the update history below.

ENCLAI counts reflect verified records available from reporting sources for the stated window. They are not estimates of total incidence and should not be interpreted as medical advice. Full methodology: the dataset.

Review and corrections

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