Until recently, the situation seemed very encouraging. In the middle of the first sad year of the corona pandemic, health experts were able to celebrate the great success of having banned polio from all of Africa. Last year it was polio again that gave reason for optimism: Six more cases of the condition, also known as poliomyelitis, or polio for short, were registered worldwide. The goal of global extinction was closer than ever.
But in the past few weeks, a whole series of unexpected and sobering developments have become known. At the end of July, a man in the US state of New York fell ill with the typical paralysis. It’s the first case of polio in the United States in almost a decade. The patient had not been vaccinated and, according to the authorities, had not traveled before. So he must have been infected in his home country, where the pathogen has long since been eradicated.
It quickly became clear that the patient had contracted the vaccine polio. It results from live vaccines that contain weakened pathogens. In rare cases, these pathogens can be passed on to unvaccinated people. In even rarer cases, if they circulate for a period of time, they can change and lose the mutation that weakened them. They regain the ability to trigger the dreaded paralysis just like the naturally occurring polio virus. In most countries, including the USA, these vaccines have therefore not been used for years.
The pathogens discovered in the USA are closely related to viruses from Great Britain and Israel
Genetic analyzes revealed another finding: the US patient’s viruses were not unknown, but closely related to viruses that had previously been discovered in sewage samples in three countries. As reported by the Global Polio Eradication Initiative (GPEI)., these virus strains had already appeared in June near the American patient’s place of residence. They were also discovered in London between February and June and in Israel around the same period. A three-year-old girl became paralyzed there at the beginning of the year. Another child tested positive for the condition but showed no symptoms. The GPEI is currently calling on all states to increase virus surveillance and ensure that the population has a high level of vaccination protection.
Because these discoveries suggest that the pathogens that made the American ill have been circulating in various places around the world for a long time. The polio virus paralyzes only one in about 200 infected people, so many infections go unnoticed.
The discoveries in London’s sewage also indicated such a silent infection process. The finds indicate that the viruses come from several people, said Philip Minor, who worked for the National Institute for Biological Standards and Control for a long time, after the reports in June: “Viruses had also been detected in the wastewater before, but it was These are isolated cases that likely came from someone who caught the virus while visiting a foreign country.” To his knowledge, the findings are the first sign of sustained poliovirus circulation in the UK since 2004, when immunizations with the live vaccine were stopped.
The classic polio diseases are also increasing again
Vaccination polio cases do not count in the official statistics used to measure the success of the eradication campaign. Ultimately, they are unavoidable as long as the older live vaccines are still being used somewhere. But the vaccine viruses can cause just as much suffering as the natural pathogens. They are now more common than diseases caused by the wild virus. Last year about 700 cases of vaccine polio were counted in more than 20 countries, most of them in Nigeria.
However, polio diseases caused by natural viruses are currently on the rise again. A total of almost 20 such cases have already occurred this year, most of them in Pakistan. At the same time, the wild virus returned to states that previously thought it had been defeated. A few days ago, Mozambique reported three classic cases of polio, one of them in the border area with Zimbabwe, which gives rise to fears of spreading to another country. A case had already surfaced in Mozambique in March. Polio was also discovered in Malawi earlier this year.
The following applies to both forms of polio: they spread where there are vaccination gaps. And these vaccination gaps have grown during the corona pandemic. 23 million children missed vaccinations in 2020, nearly four million more than a year earlier, it found an analysis by the World Health Organization and the children’s charity Unicef. About 17 million children likely did not receive any vaccination at all in the first year of the pandemic.
“Terrible, but sadly not unexpected,” said David Elliman, a pediatrician at London’s Great Ormond Street Hospital, and warned: “With communicable diseases, the impact of events in one part of the world can spill over into the entire globe.” Covid-19 has made this clear in a very dramatic way – as well as the rapid spread of monkeypox and “the worrying presence of poliovirus in sewers”.