The defeat of polio proved that immunisation saved lives, but there’s a sting to the tale | Global

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Half a century since its eradication in the west, it is hard today to appreciate the terrible effect that polio had on people’s lives then and how feared it was as a disease. The virus killed hundreds every year in the UK alone, and left thousands afflicted with long-lasting paralysis.

A list of noted figures who contracted polio in their youths reveals its global impact. Among those who suffered were Arthur C Clarke, Donald Sutherland, Mia Farrow, Francis Ford Coppola, Joni Mitchell, Neil Young, Frida Kahlo and many others.

In the end, polio was defeated, emphatically, by vaccines that were introduced in the 50s and 60s in the west and later in other parts of the planet. Today, only Pakistan and Afghanistan still suffer outbreaks caused by the wild form of the virus. The polio vaccine is proof of the power of immunisation programmes to save lives.

But there is a sting to this tale, one which has important implications for how we deal with Covid-19 in coming months. The vaccine that has so effectively dealt with polio for the past four or five decades is getting old. In a few rare cases, the disabled virus used by the vaccine to stimulate immune systems in advance of infection has mutated. The result has been the emergence of a strain, known as vaccine-derived poliovirus, which is spreading across nations.

According to the journal Science, more than 600 vaccine-derived cases of polio have been recorded this year, a fivefold increase in numbers on last year, with a total of 23 countries, most of them in Africa, now battling rising numbers of vaccine-derived polio outbreaks.

“It’s really quite worrying,” says epidemiologist Kathleen O’Reilly, of the London School of Hygiene and Tropical Medicine. “The geographic spread of cases suggests there is a lot of transmission going on now.”

A new polio vaccine has now been created to deal with these cases. It also uses a weakened live virus, but it has been genetically engineered to prevent it from mutating and becoming harmful. This new vaccine is now being tested, with funds provided by the Bill and Melinda Gates Foundation and others.

However, the vaccine is not yet licensed. Not surprisingly, this is causing frustration as vaccine-derived polio cases rise alarmingly. As a result, many doctors and scientists are now urging the World Health Organization to use its emergency-use listing process to give them the go-ahead to use the vaccine now. Given that the same WHO emergency-use listing process is likely to be used to give the go-ahead to many of the vaccines being developed to counter Covid-19, it’s not hard to see parallels between our highly charged responses to the arrival of the coronavirus and frustrated reactions to the emergence of the new strain of polio.

Both cases are urgent. With Covid-19, numbers of cases and deaths continue to spiral. Equally, the issues surrounding the new strain of polio are becoming critical, as epidemiologist Professor Nicholas Grassly, of Imperial College London, points out.

“We are currently responding to outbreaks of vaccine-derived poliovirus by using millions of doses of the old polio vaccine, yet this itself is responsible for seeding more outbreaks,” he told the Observer. “At the same time, we have got a vaccine that gets round that issue and we need to get it out into widespread use. This is the tool we need to halt the spread of vaccine-derived polio outbreaks, and it should be put into the field as a matter of urgency.”

Hafta Ichi
Source: The Guardian
Keyword: The defeat of polio proved that immunisation saved lives, but there’s a sting to the tale | Global

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