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World risk · Supply chains and chokepoints · Food, climate & health

The CDC or WHO confirms sustained human-to-human spread of H5N1 bird flu

The test Between 26 Oct 2026 and 25 Oct 2027, the US CDC or WHO states that sustained human-to-human transmission of influenza A(H5N1) has been identified.

Not under way · Confidence: medium · Reviewed 25 Oct 2026 · Scores from 1 to 10

This page answers: What could happen, how it is scored, and who is exposed?

Using this page
  1. Read the two scores: Likelihood and Impact are kept apart.
  2. Check what is happening, each fact with its source.
  3. Use the calendar for the dates to watch.

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Likelihood
3Low steady this month
Impact
9Severe steady this month
Breadth10
Depth9
Duration8
Hard to substitute7
Canada pointNot added0

Impact is the average of the four parts, rounded, plus one point when Canada is directly hit on two or more channels, up to 10.

Two separate scales from 1 to 10. Strature never multiplies or merges them.

What changed

Dated, newest first

  1. 72 US human cases since Feb 2024 (7 via flu surveillance, 65 via monitoring); public risk low. [1]
  2. US grade A egg price US$6.227 a dozen in Mar 2025, US$2.272 in Sep 2026. [6]
  3. One new human H5N1 case, a child in Bangladesh, reported 8 Aug to 6 Sep 2026; Bangladesh's fourth human A(H5) case of 2026; contacts stayed well, and the two who fell ill tested negative. [2]
  4. WOAH reports A(H5) detections in wild and domestic birds in Africa, the Americas, Asia, Europe and Oceania. [2]
  5. No reported human-to-human transmission of H5N1 since 2007; global public health risk low. [2]

Why it matters

H5N1 bird flu circulated in birds and mammals on every continent except Oceania as of 1 March 2026, and WHO's September 2026 summary lists A(H5) detections in birds in Oceania too. The US has counted 72 human cases since February 2024. WHO says no human-to-human spread has been reported since 2007, and both agencies rate the public risk low. Sustained spread between people would start a pandemic: unlikely in the next year, but severe if it happens.

Why Likelihood 3 A driver exists but is blocked: wide animal spread, 1,088 US dairy herds (as of 1 Mar 2026) and minimal human immunity push; no human-to-human spread since 2007, no efficient droplet transmission in lab studies and strong surveillance hold it down.

Why Impact 9 Threshold case: sustained spread confirmed, the start of a pandemic.

The other facts on file (4)
  • Nine more human H5N1 cases July 2025 to March 2026, eight in Cambodia. [3] (1 Mar 2026)
  • 1,204 poultry, 6,326 wild bird and nine bovine outbreaks reported to WOAH, 1 Jul 2025 to 1 Mar 2026; 1,088 US dairy herds in 19 states since 2024. [3] (1 Mar 2026)
  • Canada reported nearly 500 wild bird detections and over 80 poultry outbreaks. [3] (1 Mar 2026)
  • PABS annex talks extended to the May 2027 World Health Assembly, or a special session in 2026. [5] (1 May 2026)

Where it sits

Bab el-MandebStrait of HormuzStrait of MalaccaPanama CanalSuez CanalTaiwan Strait11. The CDC or WHO confirms sustained human-to-human spread of H5N1 bird flu: Severe impact · unlikely1 · Severe impact · unlikelyBab el-MandebStrait of HormuzStrait of MalaccaPanama CanalSuez CanalTaiwan StraitINDIAUNITED STATESINDONESIAPERUCOLOMBIAFRANCEPACIFIC OCEANINDIAN OCEANMap data: Natural Earth (public domain).
Bab el-MandebStrait of HormuzStrait of MalaccaPanama CanalSuez CanalTaiwan Strait11. The CDC or WHO confirms sustained human-to-human spread of H5N1 bird flu: Severe impact · unlikelyBab el-MandebStrait of HormuzStrait of MalaccaPanama CanalSuez CanalINDIAUNITED STATESINDONESIAPERUCOLOMBIAFRANCEMap data: Natural Earth (public domain).

How it spreads

If

Between 26 Oct 2026 and 25 Oct 2027, the US CDC or WHO states that sustained human-to-human transmission of influenza A(H5N1) has been identified.

Not under way

Channels 5 on the card

  1. CanadaShared flyways and poultry trade; over 80 poultry outbreaks July 2025 to March 2026 [3].
  2. Health and labourMinimal human immunity to the H5 part of the virus [3] means wide reach.
  3. World economyCOVID-19 guide: the IMF projected -3% world growth in 2020 and a US$9 trillion loss over 2020-21 [7].
  4. FoodPoultry losses already moved US egg prices; a pandemic adds travel and labour shocks.
  5. Supply chains and rulesBorder checks, export bans and vaccine nationalism; pandemic sharing rules not in force.

Goods 3

  • Eggs
  • Poultry
  • Milk

Sectors 3

  • Agriculture and food
  • Banks and insurers
  • Ports and logistics

Who is exposed

Countries
United States, Cambodia, Bangladesh, Canada, Mexico, European Union
Sectors
Agriculture and food, Banks and insurers, Ports and logistics
Goods
Eggs, Poultry, Milk

Three scenarios and their signposts

  1. S1

    Sporadic cases

    Animal outbreaks continue with a handful of human cases and no spread.

  2. S2

    A cluster

    A small cluster with limited spread between people, contained.

  3. S3

    Sustained spread

    The CDC or WHO confirms sustained transmission.

The signposts of each scenario
PathSignpost
S1WHO monthly summaries keep the risk at low
S2WHO reports a cluster where human-to-human transmission could not be excluded
S3CDC raises its public risk rating above low

No probability is given for the three paths.

Dates to watch

Calendar

The dates to watch

A dot is a day, a bar a month or a year; a hollow mark is tentative. The line marks today.

  1. Oct 2026 Northern bird migration season to March 2027 (risk window) [3] Tentative · Window
  2. Nov 2026 WHO monthly summary on influenza at the human-animal interface [4] Tentative · Outside event
  3. 10 Nov 2026 US egg price for October 2026 released [6] Declared · Outside event

    Remind me

  4. May 2027 World Health Assembly due to receive the pathogen-sharing annex (or a special session in 2026) [5] Declared · Outside event

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SourceStrature world-risk card; the dates cite the sources below.
Exhibit R-3 · WORLD · strature.net

The other side

Years of animal outbreaks have built tools: WHO keeps candidate vaccine viruses under review [3], and US and Canadian surveillance catches cases early [1][3]. Countries with vaccine and diagnostics capacity would be suppliers in a pandemic.

Connected in Strature

Sources

7 sources, numbered as the text cites them

  1. H5 Bird Flu: Current Situation. US CDC · 15 Oct 2026 · Official · confidence high · retrieved 25 Oct 2026
  2. Influenza at the human-animal interface: summary and risk assessment, 8 August to 6 September 2026. World Health Organization · 6 Sep 2026 · International body · confidence high · retrieved 26 Oct 2026
  3. Updated joint FAO/WHO/WOAH public health assessment of recent HPAI A(H5) virus events in animals and people. FAO, WHO and WOAH · 18 May 2026 · International body · confidence high · retrieved 25 Oct 2026
  4. Monthly risk assessment summary. World Health Organization · 6 Sep 2026 · International body · confidence high · retrieved 25 Oct 2026
  5. WHO Member States agree to extend negotiations on Pathogen Access and Benefit Sharing annex. World Health Organization · 1 May 2026 · International body · confidence high · retrieved 25 Oct 2026
  6. Average Price: Eggs, Grade A, Large, U.S. City Average (APU0000708111). US BLS via FRED · 14 Oct 2026 · Official · confidence high · retrieved 25 Oct 2026
  7. The Great Lockdown: Worst Economic Downturn Since the Great Depression. IMF Blog · 14 Apr 2020 · International body · confidence high · retrieved 25 Oct 2026

Reviewed 25 Oct 2026 · version 1 · last change: reviewed · All risks