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Yellow fever

Yellow fever spreads fast, often leading to epidemics with devastating consequences for densely-populated cities. GAVI funds help countries with routine immunisation as well as ensuring emergency stockpiles are available to prevent sudden epidemics.

What is yellow fever?

There is no cure for this viral fever, transmitted by mosquitoes, and no treatment beyond supportive care. Epidemics in unvaccinated populations can result in the death of more than half the infected adult population and up to 70 percent of infected children.

First symptoms usually appear three to six days after infection and are characterised by fever, muscle pain, headache, shivers, loss of appetite, nausea and vomiting. After four to six days, most patients improve and symptoms disappear.

However, in a few cases, the disease enters a toxic phase. The fever reappears and the patient develops jaundice, hence the name "yellow". Sometimes blood appears in vomit. About 50 percent of patients who enter the toxic phase die within 10-14 days.

Who is at risk?

Mass vaccination campaigns in the mid-20th century controlled the disease for over 40 years. With results thought to be permanent, large-scale immunisation ceased. However, the disease remained hidden in mosquito-ridden forests in Africa and the Americas, and, from the late 1980s onwards as populations became more urbanised, it re-emerged in cities where people were no longer immunised.

The World Health Organization (WHO) estimates that yellow fever causes 200,000 cases and 30,000 deaths each year.

Where?

The countries most at risk lie in tropical regions of Africa and the Americas, but the vast majority of cases and deaths are concentrated in a belt of 12 African countries: Benin, Burkina Faso, Cameroon, Côte D’Ivoire, Ghana, Guinea, Mali, Nigeria, Senegal, Sierra Leone, Togo and Liberia.

The vaccine

Since 1937, there has been a safe, highly effective vaccine against yellow fever offering 10 years’ protection.

WHO recommends a two-pronged preventive vaccination strategy:

  1. The vaccine should be included in national childhood routine immunisation programmes and given at nine months of age along with the first dose of the measles vaccination
  2. Mass campaigns should be implemented to ensure faster immunisation of susceptible populations.

To prevent an epidemic WHO estimates 60 to 80 percent of the target population needs to be immunised.

When an outbreak occurs, response immunisation should be done as soon as possible to reduce the spread of the disease.

GAVI’s response

GAVI has allocated US $58.6 million to the so-called Yellow Fever Initiative. This three-pronged approach consists of:

  • increasing dramatically the size of the global yellow fever vaccine stockpile, stored with its manufacturers in Brazil, Senegal and France.

    The 12 countries eligible for GAVI funding that are most at risk of yellow fever can draw from this stockpile to carry out preventative vaccination campaigns. In response to a sudden yellow fever outbreak, any country in the world can draw immediately on the stockpile. Both in preventative and emergency campaigns, the 72 “GAVI” countries do not need to replenish the stockpile.

  • funding part of the operational costs of campaigns;
  • supporting WHO assessments that identify high-risk populations.

GAVI also supports routine yellow fever immunisation. This enables eligible countries to top up their vaccination programmes, if coverage is lower than that for measles. See which countries have had their applications to GAVI for yellow fever support approved.