Avian influenza A: What the US Data Actually Shows

The published figures

Every number below is reproduced from a primary source and carries that source beside it. Where a figure is absent it is shown as unavailable rather than estimated — the reasoning for each gap is set out further down this page.

70 is a cumulative outbreak total (April 2024 onward) rather than a clean annual figure. CDC's situation summary (updated March 6, 2026) reports 71 A(H5) cases and 2 deaths since February 2024 across all H5 subtypes; one of those — the November 2025 Washington case — was confirmed as A(H5N5), not H5N1 (WHO DON 590, 5 December 2025), so the H5N1 figures are 71 − 1 = 70 cases and 2 − 1 = 1 death. WHO's cumulative H5N1 table (data as of 7 August 2026) agrees: United States 67 cases / 1 death with 2024 onset, 3 / 0 in 2025, 0 in 2026. CDC's exposure breakdown of the 71: 41 dairy herds, 24 poultry farms and culling operations, 3 other animal exposure, 3 unknown. No human-to-human transmission identified. cases_per_100k and case_fatality_rate_pct are derivations per SITE-PLAYBOOK.md §12a from the March 19, 2025 CDC update — the counts have not changed since, so the inputs stand — both explicitly labelled as covering the outbreak-to-date window (not a calendar year) and, for CFR, the mild US outbreak specifically (not the far higher global historical H5N1 rate).

How these figures were calculated

One figure above is arithmetic rather than a number lifted straight from an agency page. Both inputs are given below with their own source, geography, and reporting period, so the calculation can be checked rather than taken on trust. A derived figure is never rated more reliable than its weakest input.

What this data cannot tell you

2 of the five funnel metrics have no publishable US figure for Avian influenza A. That is a deliberate result, not an oversight. Where no primary source publishes a comparable figure, this site leaves the cell empty rather than filling it with an estimate, a number borrowed from a different population, or a single-study result presented as a general rate.

• Severe Outcome Rate — no comparable figure published by the record's primary source as of 2026-03-06.
• Hospitalization Rate — no comparable figure published by the record's primary source as of 2026-03-06.

This matters when comparing viruses. A blank cell is not a low number: it means the measurement does not exist, and treating it as zero would make Avian influenza A look safer than the evidence supports. The comparison table on the Virus Risk Perspective page applies the same rule — unavailable figures are excluded from ranking rather than sorted to the bottom.

How Avian influenza A compares

Ranked only against viruses in this collection that publish the same metric. Viruses without a published figure are excluded from each comparison rather than counted as zero, so the denominator differs from metric to metric.

Read the case comparison carefully. Records in this collection do not all measure exposure the same way. Some report confirmed cases counted by a surveillance system (measles, West Nile), others a modelled estimate of total annual illness including cases that are never reported (norovirus, seasonal influenza). A modelled burden figure will always dwarf a confirmed-case count, so a gap on this metric can reflect how a disease is counted as much as how often it occurs. The per-figure sources above state which basis each number uses.

How the figures have moved

Each observation below is a figure as it stood on a given date, with the source that published it. Points are not interpolated: where an agency published a figure once, one point is shown rather than a line drawn through invented values.

Global picture

WHO's cumulative table of confirmed human A(H5N1) cases (data in WHO HQ as of 7 August 2026) gives 30 cases and 12 deaths with onset in calendar year 2025 — the latest complete year — and 1,002 cases / 479 deaths in total since 2003 (for the United States it counts cases reported as A(H5) too). 2026 to 7 August: 9 cases, 2 deaths (partial year, not charted). Annual counts by onset year, 2020–2025: 1, 2, 6, 12, 81, 30 cases and 0, 1, 1, 4, 4, 12 deaths. CDC's own tally (June 26, 2026) is 1,022 cases worldwide since 1997. The WHO Influenza (avian and other zoonotic) fact sheet, re-dated 21 January 2026 and re-read 2026-09-15, still gives no precise total ("hundreds of human cases, and many deaths"), so the table is cited instead. Surveillance confidence is low: only laboratory-confirmed cases are counted and testing of mild illness varies widely by country.

Source: WHO — Cumulative number of confirmed human cases for avian influenza A(H5N1) reported to WHO, 2003–2026 (data as of 7 August 2026) · Data as of 2026-08-07 · Surveillance confidence: low

Sources

• CDC — A(H5) Bird Flu: Current Situation (updated March 6, 2026) primary source · retrieved 2026-03-06
• CDC — A(H5N1) Bird Flu Response Update, March 19, 2025 (deaths ÷ cases, both cumulative US outbreak totals) primary source · retrieved 2025-03-19
• WHO — Cumulative number of confirmed human cases for avian influenza A(H5N1) reported to WHO, 2003–2026 (data as of 7 August 2026) primary source · retrieved 2026-08-07

Sourcing tiers, and the rule that a derived figure inherits its weakest input's tier, are set out on the Our Sources page. The process behind every figure is described in How We Answer Questions.