By Michael Le Page
On 10 January, renowned cancer doctor Martin Gore of the Royal Marsden Hospital in London died of organ failure shortly after getting the yellow fever vaccine, according to the Times newspaper. This has led to concern about the vaccine’s safety, particularly for older people – Gore was 67. Here’s what we know:
What is yellow fever?
It’s a mosquito-borne virus found in Africa, South America and the Caribbean. People infected with the virus develop flu-like symptoms. About 85 per cent of people recover but in 15 per cent it damages the liver and kidneys, causing internal bleeding that is often fatal. In recent years there have been a series of outbreaks in Africa, leading to a vaccine shortage. There are also fears the virus could spread to Asia.
Did the yellow fever vaccine cause Gore’s death?
We don’t know, contrary to some reports. The case should now go to the agency responsible for vaccine safety in the UK, the Medicines and Healthcare products Regulatory Agency, which will determine if the vaccine was the cause of death.
Could the vaccine have killed him?
Yes, although it is exceedingly unlikely. The yellow vaccine is a live vaccine – a harmless variant of the wild virus. In around 1 in 250,000 people, according to the US Centers for Disease Control (CDC), it causes “yellow fever vaccine-associated viscerotropic disease” – serious damage to internal organs.
How many people have died as a result of the vaccine?
Of the hundreds of millions given the yellow fever vaccine since it was introduced in 1936, there have been just 62 confirmed cases and 35 deaths from vaccine-associated viscerotropic disease, according to a 2016 study. It’s likely that cases have been missed in poor countries, but because the condition is so serious it is unlikely to go unnoticed in rich countries.
Are there other risks of having the vaccine?
About one person in 55,000 experiences a severe allergic reaction to a vaccine component and one person in 125,000 experiences severe nervous system reaction. So overall the risk of serious side effects is very low, but still higher than other vaccines, where the risk is typically one in several million, says Ron Behrens of the London School of Hygiene & Tropical Medicine.
Are older people more vulnerable?
Yes, it appears people aged over 55 are several times more likely to develop vaccine-associated viscerotropic disease than younger people, although the overall risk remains very low. According to a 2013 paper, vaccination of older people should be based on a careful risk-benefit analysis.
So should people get the vaccine?
Behrens thinks all travellers – whatever their age – should weigh the risks of vaccination versus the risks of getting the disease, and decide for themselves, although in some countries it is mandatory for entry. He points out that people travelling to countries like Kenya, where there have been no cases of yellow fever for decades, are often still advised to get vaccinated. Yet in this case the risks of vaccination may outweigh the benefits.
But isn’t it selfish not get vaccinated?
It is if you live in a country where a disease is spreading. But travellers visiting an area for a week or two are very unlikely to get ill and spread yellow fever to others. Cases in returning travellers are extremely rare, says Behrens. “In this case, the vaccination is for your own benefit.”
What causes yellow fever vaccine-associated viscerotropic disease?
We don’t know. The leading hypothesis is that a few rare individuals have little defence against the vaccine strain of the virus, so it does as much damage as the wild virus.
Can it be prevented?
In theory, a vaccine that does not contain a live virus might prevent all cases of vaccine-associated viscerotropic disease. A 2010 paper called for the replacement of the current yellow fever vaccine for this reason, and a number of new vaccines are already being tested. But establishing the safety and efficacy of new vaccines takes time and money.
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