ONLY PUBLIC HYSTERIA – AND NOT THE VACCINES – DOES MORE HARM THAN GOOD
The sudden death of a leading cancer expert after a routine inoculation for yellow fever has reignited one of the biggest controversies in medicine – how safe are vaccines?
Prof Martin Gore of the Institute of Cancer Research in London suffered total organ failure shortly after receiving the vaccine, and died last week.
While his death is still under investigation, attention has focused on the vaccine as the most likely cause.
The incident has reopened a long debate on whether the benefits of vaccines outweigh the potential risks, and offered new insight into how the public can be swayed by raw emotion and mass media outrage.
It is believed Gore, 67, had the vaccination prior to travelling to a region where yellow fever is endemic.
The lethal, mosquito-borne disease is common in tropical regions of Africa and Central and South America, and kills up to 50 per cent of those who develop the full-blown disease.
But since the 1930s, a vaccine has been available that offers life-long protection. Over the decades, the shot has protected hundreds of millions of people.
Like all vaccines, however, the protection is not without risks. It causes mild side effects including headaches and a fever in about one in three of those who receive it.
But in about one in 250,000 cases, it triggers symptoms very similar to yellow fever, including kidney and liver failure, leading to the jaundice that gives the disease its name.
These risks are substantially higher for those over the age of 60, such as Gore.
Despite the risk being considered more than 1,000 times lower than the risk of dying from the disease, some experts believe they are enough to justify avoiding travel to infected countries.
Whether Gore was aware of this fact is not known. What is clear is that for many people, vaccination involves making decisions that are based on more than numbers.
Attitudes to the risks involved can be dictated by subjective concerns that scientists often underestimate.
One crucial concern is the effect from media coverage and the fact that even rare events will eventually occur.
This has profound implications for public health measures such as vaccinations, which routinely involve millions of people.
And when rare events do occur, they often gather media coverage because they are linked to something familiar to many of us.
In 2008, many countries – including the UAE – began offering young women vaccinations against human papillomavirus, the virus responsible for cervical cancer.
Within months, the UK media reported the case of a girl, 14, who had died within hours of receiving the vaccine.
The coverage prompted calls for the programme to be abandoned.
But doctors found the girl succumbed to an undiagnosed malignant tumour, making her death a tragic coincidence unrelated to the vaccine.
The coverage, however, sparked public concern that probably deterred many from getting the proven protection offered by the vaccine.
Scientists stress that risk assessments cannot be based on anecdotes, and must be put in context. Yet evidence suggests many people find anecdotes more compelling than numbers.
During his campaign for the US presidency, Donald Trump repeatedly claimed that a vaccine given to children to protect against mumps, measles and rubella was linked to autism.
Mr Trump’s claims became the focus of a US Republican primary TV debate in 2015.
Rival candidate Dr Ben Carson, a retired neurosurgeon, insisted many studies had failed to find “any correlation between vaccinations and autism”.
In response, Mr Trump told a story of how a child of someone he knew was given the vaccine, and a week later “got a tremendous fever, got very, very sick, and now is autistic”.
Even scientists conversant with the facts conceded to finding Mr Trump’s personal anecdote more immediately compelling than Dr Carson’s facts.
Some researchers say this is because humans have spent far longer understanding the world through stories than through data. The best advice is perhaps to follow the scientific maxim that the plural of anecdote is not data.