47% fewer hepatitis b cases in the US: 957 in the last 30 days

The full briefing

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

The US reported 4,410 hepatitis b cases in the 90 days to 22 September. 957 of them came in the 30 days to 22 September, against 1,802 in the 30 days before. The same 30 days a year earlier had 2,542.

Why it matters

The US accounts for 5.7% of the hepatitis b cases reported to ENCLAI worldwide so far in 2026. It ranks 2 of 19 reporting countries. 2025 closed at 22,681 cases, 5108% above the three-year baseline of 436 a year. 2026 so far stands at 20,616.

The numbers

Period	Reported cases
Last 30 days (to 22 September)	957
The 30 days before that	1,802
Same 30 days a year earlier	2,542
90 days to 22 September	4,410
2026 so far (ENCLAI export)	20,616
Three-year baseline (a year)	436

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

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

Retained reporting context

Sources and limitations

• ENCLAI surveillance dataset — methodology, coverage and limitations (ENCLAI · 2026-09-22)
• Data sources — aggregate coverage by region and source type (ENCLAI · 2026-09-22)

• 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

• Editorial review. Reviewed and approved for publication by Dr Natalya Mathur (MD), Founder, Enclai, on 22 Sep 2026.
• Update history. No corrections or updates have been issued for this briefing.
• Spotted an error? Tell us and we will correct it on the record.

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