LONDON (AP) — The baby in Gaza recently paralyzed by polio was infected with a mutated strain of the virus that vaccinated people shed in their feces, according to scientists who say the case is the result of “an unqualified failure” of public health policy.
The infection, which marked the first detection of polio in the war-torn Palestinian territory in more than 25 years, paralyzed the lower part of one leg in the unvaccinated 10-month-old. The baby boy was one of hundreds of thousands of children who missed vaccinations because of fighting between Israel and Hamas.
Scientists who have monitored polio outbreaks said the baby’s illness highlighted the failures of a global effort by the World Health Organization and its partners to address serious problems in their otherwise largely successful eradication campaign, which has nearly wiped out the highly contagious disease. Separately, a draft report from experts called the WHO effort a failure and “a serious setback.”
The polio strain in question originated from a weakened virus that was originally part of an oral vaccine that saved millions of children worldwide from paralysis. But that virus was removed from the vaccine in 2016 in hopes of preventing vaccine-related outbreaks.
Public health authorities knew this move would leave people unprotected against that particular strain, but they thought they had a plan to head off and quickly contain outbreaks. Instead, the move resulted in thousands of cases.
“It was a terrible strategy,” said virologist Vincent Racaniello of Columbia University, who was not involved in the report or the WHO. “The decision to switch vaccines was based on a false premise, and the result is that we now have more polio and more paralyzed children.”
A draft version of the report, commissioned by the WHO and independent experts, said the plan underestimates the scale of the environmental burden and overestimates how well authorities could suppress outbreaks.
The plan led to vaccine-induced polio outbreaks in 43 countries, paralyzing more than 3,300 children, the report found.
Even before the Gaza case was discovered, officials assessing the initiative to tinker with the vaccine concluded that “the worst-case scenario had materialized,” the report said.
According to the WHO, the report has not yet been published and some changes are likely to be made before the final version is published next month.
The strain that infected the baby in Gaza had lingered in the environment and mutated into a version capable of causing outbreaks. It was traced to polioviruses that spread in Egypt last year, through genetic sequencing, the WHO said.
In 2022, vaccine-linked polioviruses were discovered spreading in Britain, Israel and the US. An unvaccinated man was left paralyzed in upstate New York.
Scientists are concerned that polio could spread further if the virus emerges in a war zone with an undervaccinated population.
Racaniello said the failure to accurately track polio and adequately protect children from the strain removed from the vaccine has had devastating consequences.
“Only about 1% of polio cases are symptomatic, so 99% of infections spread the disease silently,” he said.
The oral polio vaccine, which contains a weakened live virus, was withdrawn in the U.S. in 2000. Doctors continued to vaccinate children, eventually switching to an injected vaccine, which uses a dead virus and does not carry the risk of polio being present in human waste. Such a waste-borne virus could mutate into a form that causes outbreaks in unvaccinated people.
The report’s authors criticized leaders at WHO and its partners, saying they were unable or unwilling “to recognize the seriousness of the evolving problem and take corrective action.”
WHO spokesman Oliver Rosenbauer acknowledged that the vaccination strategy “exacerbated” the risk of vaccine-related epidemics.
He said in an email that immunization “was not implemented in a way to quickly stop outbreaks or prevent new strains from emerging.” Rosenbauer said missing vaccination targets was the greatest risk for the emergence of vaccine-related viruses.
“You have to reach the children with the vaccines…regardless of which vaccines are used,” he said.
The WHO estimates that 95% of the population needs to be vaccinated against polio to stop outbreaks. The UN health agency said that only about 90% of Gaza’s population had been vaccinated earlier this year.
To stop polio in Gaza and the wider region, WHO and its partners are planning two rounds of vaccination campaigns later this week and next month, with the aim of covering 640,000 children. Authorities will use a newer version of the oral polio vaccine that targets the problematic strain. The weakened live virus in the new vaccine is less likely to cause vaccine-related outbreaks, but they are still possible.
Racaniello said it was “unethical” for WHO and its partners to use a vaccine that is not approved in wealthy countries, precisely because it could increase the risk of polio in unvaccinated children.
The oral polio vaccine, which has reduced infections by more than 99% worldwide, is easy to make and distribute. Children need only two drops per dose, which can be administered by volunteers. The oral vaccine is better at stopping transmission than the injected version, and it is cheaper and easier to administer.
But as the number of cases of polio caused by the wild virus has declined sharply in recent years, health officials have struggled to contain the growing spread of vaccine-related cases, which now account for the majority of polio infections in more than a dozen countries, along with Afghanistan and Pakistan, where transmission of the wild virus has never been contained.
“This is the result of the Faustian bargain we made when we decided to use the oral polio vaccine,” said Dr. Paul Offit, director of the Vaccine Education Center at the University of Philadelphia. “If we really want to eradicate polio, we have to stop using the live (attenuated) virus vaccine.”
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