Yellow Fever Epidemiology Forecast 2026-2035

Parameter

Insight

Largest Patient Pool

France

Fastest Growing Country

France

High-Risk Population

Within the eight countries, the principal high-risk groups are unvaccinated travellers visiting yellow fever transmission-risk areas, people with prolonged exposure in forested or rural environments where infected mosquitoes circulate, and individuals whose travel or residence history places them at risk of infection. People with contraindications to live yellow fever vaccine require individualized travel-health assessment.

Key Diagnostic Method

Laboratory confirmation using molecular or serological testing is central to yellow fever diagnosis. Reverse-transcription polymerase chain reaction (RT-PCR) can detect viral RNA early in illness, while serological testing can identify yellow fever-specific antibodies later in the course.

Major Risk Factor

The principal risk factor is travel to or residence in an area with active yellow fever transmission without effective vaccination. In the eight markets, imported infections are the main concern in settings without established local transmission. Risk is influenced by travel destination, duration and type of outdoor exposure, mosquito activity, and vaccination status.

Major gap in the market

The principal gap is the limited comparability of recent country-specific case data and the low likelihood of detecting every imported infection promptly. Yellow fever is rare in most of the eight markets, so surveillance often relies on clinical suspicion, travel histories, and specialist laboratory confirmation.

Epidemiology Segment

Key Insights

Diagnosed Prevalent Cases of the Disease

Yellow fever is an acute infection, so annual confirmed cases and place of acquisition are more meaningful epidemiological measures than conventional diagnosed prevalence. The UK Health Security Agency reported no yellow fever cases in England, Wales, and Northern Ireland in 2023 or 2024.

Gender-Specific Cases of the Disease

Comparable 2023-2026 sex-disaggregated yellow fever case counts were not identified across the eight countries. The small number of cases expected in non-endemic settings makes it difficult to infer meaningful sex-related differences from sporadic notifications. Risk is more directly associated with vaccination status, travel destination, exposure to infected mosquitoes, and relevant clinical factors than with sex alone.

Age-Specific Cases of the Disease

A comparable age-specific distribution of yellow fever cases was not established for the eight countries from 2023-2026 sources. In these settings, case numbers are shaped mainly by travel-related exposure and vaccination status, so sporadic cases cannot reliably establish a national age profile. Age remains clinically important when assessing vaccination eligibility and the risk of rare serious vaccine-associated adverse events.

Ethnicity-Wise Cases of the Disease

Ethnicity is not an appropriate substitute for individual exposure history: travel destination, residence in an area with transmission, vaccination status, and mosquito exposure are more relevant to risk assessment. Any differences in reported cases should be interpreted in the context of travel patterns, access to vaccination, and surveillance coverage rather than attributed to ethnicity without supporting evidence.

Mortality and Survival Analysis of the Disease

Severe yellow fever can progress to jaundice, haemorrhage, liver and kidney dysfunction, shock, and death. In clinical assessment, early recognition of severe disease and supportive hospital care are essential; mortality estimates from transmission-endemic regions should not be transferred to these countries.

Country

Key Insights

United States

Yellow fever is not an established source of ongoing domestic transmission in the country, and surveillance focuses on suspected and confirmed cases, including infections acquired during travel. The US National Notifiable Diseases Surveillance System publishes provisional case reports, but these should not be treated as a prevalence estimate without a verified annual total and a defined denominator. A numerical prevalence percentage is therefore not assigned.

Germany

In a setting without established local transmission, the relevant measures are confirmed imported cases, travel-related exposure, and access to vaccination before travel. No recent, nationally representative denominator-based estimate was verified for Germany, so a prevalence percentage or diagnosed-patient count would be unsupported. Surveillance should distinguish infections acquired abroad from any suspected locally acquired transmission.

France

Mainland France is primarily concerned with imported cases, while French Guiana has a different yellow fever exposure context. A comparable 2023-2026 population-prevalence estimate covering the requested French geography was not established from the reviewed sources. National reporting should specify the territory, place of acquisition, vaccination history, and denominator before any prevalence percentage is assigned.

Italy

In the absence of established ongoing local transmission, surveillance of travel-associated infections is more informative than a conventional prevalence measure. Any reported cases should be interpreted by year, laboratory confirmation, and probable place of acquisition. A national prevalence percentage or total infected population cannot be responsibly assigned without a recent, verified Italian surveillance source.

Spain

For epidemiological monitoring, confirmed imported cases and the location where infection was acquired are the relevant indicators; sporadic travel-related cases would not demonstrate sustained domestic transmission. A recent, nationally representative estimate with a defined population denominator was not verified, so no numerical prevalence is assigned.

United Kingdom

The UK Health Security Agency reported zero yellow fever cases in England, Wales, and Northern Ireland in both 2023 and 2024. Its 2024 travel-associated infection report, updated in March 2026, confirms that these figures concern reported confirmed and probable cases in the specified jurisdictions. They should not be interpreted as evidence of zero exposure risk or as a population-prevalence estimate.

Japan

Epidemiological monitoring is principally concerned with imported infection, vaccination of eligible travellers, and preventing introduction into areas where competent mosquito vectors may be present. No recent, verified national case count sufficient to calculate a prevalence rate was established in the reviewed evidence. Japan’s epidemiology entry should therefore state that a reliable current population-prevalence estimate is unavailable rather than assign a numerical value

India

The available evidence does not establish a current national burden of confirmed yellow fever cases, and a numerical prevalence should not be inferred from travel-related risk or vaccination requirements. For India, relevant surveillance priorities include prompt investigation of suspected imported cases, laboratory confirmation, and assessment of travel history and vaccination status.