The WHO declares the eradication of wild polio in Africa

On Tuesday, the world celebrated a rare piece of good news from 2020: The World Health Organization (WHO) announced that the wild poliovirus has been eradicated from Africa.

The milestone comes after three years went by without a single case of wild polio recorded anywhere on the continent (there are still so-called vaccine-descended cases circulating, though — more on that below). It brings us one step closer to the worldwide eradication of polio; however, that achievement is still a ways away.

The eradication of a major disease is huge news, and it’s not a common event. In the 1970s, the world came together in a concerted global campaign to eradicate smallpox, which the WHO officially certified in May 1980. It was an enormous accomplishment, both for global public health and for the power of countries working together to solve one of the world’s greatest problems.

But it’s one we haven’t duplicated in the more than 40 years since. Efforts to eradicate diseases have run aground on both technical difficulties and political ones. In polio’s case, the disease is harder to eradicate than smallpox because in rare cases, the vaccine can give rise to a case of the disease. Meanwhile, the cause of polio eradication was dealt a setback in the 2000s when the CIA, during the Obama administration, used a fake vaccination program as part of the effort to track down Osama bin Laden.

The WHO’s announcement Tuesday is a reminder that progress continues, albeit at a bumpy, frustrating, and sometimes disappointing pace. And although eradication of diseases may be hard, requiring global coordination on a scale it is easy to feel pessimistic about these days, it’s achievable — and well worth the effort. Once a disease is gone from the world, we never have to devote public health resources to it again. It can never again take or change another life, allowing humanity to move on to the next target on the list.

The global fight against polio, explained

Polio is caused by a virus, usually contracted in childhood, and often results in paralysis and can lead to death.

In the early 20th century, massive outbreaks of polio devastated communities in the United States and around the world. One New York outbreak in 1916 caused 9,000 cases and 2,400 deaths, mostly of children. Terrified New Yorkers, unsure of what caused the virus, engaged in mass killings of cats and dogs believed to transmit the disease. (They also took more sensible measures to fight the spread of a contagious virus, like shutting down schools and movie theaters.)

By the 1950s we understood polio a little better, and researcher Jonas Salk had developed a vaccine he thought would be safe and effective against the disease. In 1952, a devastating outbreak in the US saw nearly 58,000 cases and more than 3,000 deaths. The following year, the vaccine was introduced in one of the first large-scale, randomized controlled trials in history: 1.83 million American children received either the vaccine or a placebo.

Studies demonstrated that the Salk vaccine worked. Other researchers developed a more effective vaccine that could be orally administered rather than injected, making it easier to deploy on a mass scale. The country’s outbreak was brought to a halt, and by the 1970s, the scourge of polio was nearly gone from the US. At the same time, the fight went worldwide, and more and more countries drove the disease from their shores throughout the 1980s and ’90s.

But there was a complication, albeit a mild one. The oral polio vaccine contains a live virus, which can (very, very rarely) mutate back into a harmful form, causing the vaccinated child to become sick. This is estimated to happen about once every 2.7 million doses.

And if a vaccinated person with a mutated transmissible form of the virus lives in an area with very low vaccination rates, the virus can start circulating in the community again. This is even rarer. Since 2000, 10 billion vaccine doses have been administered, and there have been 24 outbreaks of circulating vaccine-derived poliovirus. Sufficient vaccination makes these outbreaks all but impossible, as the mutated virus does not get the chance to start circulating in the first place. But this scary side effect, while exceptionally rare, has led to fears of the vaccine in a few developing countries, as has viral misinformation about other side effects and rumors that it’s a Western plot to sterilize Muslims.

All of this has made eradication more complicated. Tuesday’s declaration specified that the wild poliovirus had not been observed on the African continent for three years — but the continent has still experienced outbreaks of vaccine-derived poliovirus. For true eradication, we’ll need to stamp those out, too. In recent years, the global eradication effort has decided to switch from oral vaccines to injected ones, which do not present a risk of the virus mutating.

Paying the price of a fake vaccine campaign

The other barrier to global eradication is polio’s prevalence in rural Afghanistan and Pakistan. Vaccination efforts in those areas have not been comprehensive enough to keep a lid on the virus.

For a long time, vaccination in that region was made difficult by poverty, suspicion of aid workers, and ongoing violence. During the Obama administration in 2011, the Guardian reported that the CIA had tried to confirm bin Laden’s location by using a fake hepatitis vaccination campaign to obtain DNA samples it hoped would confirm the identity of his children in a Pakistani compound.

The effects of this deception on polio eradication efforts in the area were catastrophic. Local militants began attacking health workers delivering polio vaccines, suspecting them of being US spies. International aid organizations were forced to suspend their vaccination efforts.

Polio cases spiked immediately. “Release of this information has had a disastrous effect on worldwide eradication of infectious diseases, especially polio,” read a 2014 editorial in the Lancet medical journal. “News of the vaccination program led to a banning of vaccination in areas controlled by the Pakistan Taliban, and added to existing skepticism surrounding the sincerity of public health efforts by the international health community. Consequently, the WHO declared that polio has reemerged as a public health emergency in Pakistan.”

The White House later stated that the US would stop using fake vaccine programs for espionage, but the damage had been done. In the next few years, at least 70 polio vaccine workers in the region were murdered. To this day, the Taliban bans polio vaccination and shoots health workers who try to provide it. There has been no accountability for the Obama administration’s decision to authorize a fake program for military purposes, and public trust in the region hasn’t recovered.

An embattled eradication effort still worth fighting for

This year, the ongoing battle against the poliovirus was further complicated by fears of spreading the coronavirus, which brought much of the world’s public health initiatives against polio to a halt. “We did not want to have the program be responsible for worsening the situation with Covid-19,” Michel Zaffran, head of the WHO’s Global Polio Eradication Initiative, told Science magazine in April. But without vaccination, polio resurges quickly.

“The numbers look awful for eradication,” Hamid Jafari, who leads the WHO’s polio eradication efforts in Pakistan and Afghanistan, said in July. With both wild polio and vaccine-derived polioviruses circulating, and with little immunity to the latter, affected regions could see vaccine-derived polio “going up to the thousands of cases if we don’t intervene,” Jafari added.

Vaccine-derived polioviruses continue to circulate in Africa, too, and efforts to keep a lid on outbreaks have been damaged by coronavirus-related pauses in polio response. The milestone the WHO announced on Tuesday is real, but in many ways this year was a setback for polio eradication.

Despite all of those challenges, there’s something important to celebrate here. A century ago, the world was ravaged by a terrifying disease about which we understood nothing. It targeted mainly children, killing them or leaving them paralyzed for life. In the century since then, we learned how polio worked and how to fight it.

We embarked on a breathtakingly ambitious campaign to make sure it would never kill a child again.

And while we’re not quite there, the eradication of wild polio from the continent of Africa is a genuine cause for celebration. “It is a vivid reminder that vaccines work and that the collective actions of communities, governments, and partners can bring about tremendous changes,” Dr. Matshidiso Moeti, WHO’s regional director for Africa, said in a Zoom call announcing the news.

Sometimes — despite our mistrust and suspicion, and despite wrongdoing by government and violence by militants — we’re able to make the world a safer one for children. We can be proud of that, even as we’re careful not to underestimate the work ahead.

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