‘Never give up’: why the fight against polio in the world is not over | Polio


AAs an eight-year-old, Anita Ghai was buried up to her neck in a mud grave during a solar eclipse, while her mother was pressured to sing verses from Hindu scriptures – ostensibly to cure Ghai of polio, which she contracted at the age of two. “I still carry guilt – for what my mother had to go through because of me,” said Ghai, now 67 and a dean at Ambedkar University in Delhi.

Such nightmares, Ghai thought, were over when the World Health Organization declared India — home to half of the world’s 2009 polio cases — free of the disease in March 2014. Yet eight years later, a disturbing series of events is unfolding around the world. Pakistan has witnessed a string of new cases, ending a 15-month period without a single new case of polio. The wild virus from Pakistan has led to infections in Mozambique and Malawi, previously free of the disease.

In June, the WHO reported cases of vaccine-derived polio — in which an attenuated virus contained in the vaccine itself spreads into the environment and infects humans — in Eritrea, Ghana, Togo, Ivory Coast, Israel, Yemen, Nigeria and the Democratic Republic of the United States. States. Congo. And in July, a patient in suburban New York was diagnosed with vaccine-based polio. Traces of this form of the virus have also been found in sewage samples in Kolkata and London for the past six weeks.

Health workers wait with a polio vaccination box at a train station in Kolkata, India.
Health workers with a box of polio vaccinations at a train station in Kolkata, India. Photo: Piyal Adhikary/EPA

These seemingly unrelated cases point to a common threat: Global polio vaccination levels fell to their lowest in 15 years in 2021, according to WHO data, with immunization initiatives disrupted during Covid. India and Indonesia, two of the world’s most populous countries, have witnessed particularly sharp declines in vaccination rates.

That makes the recent spate of cases a canary in a coal mine, experts say — warning that the crippling disease that has been eliminated from most of the world could return, especially in densely populated areas, unless countries redouble their efforts. doubling vaccinations and surveillance.

“It was pretty scary,” said virologist T. Jacob John, one of the founders of India’s polio vaccination program, of the virus trail found in Kolkata’s sewers. “A few more cases like that and we could have looked at an outbreak.”

That’s not just a hypothetical scenario: Papua New Guinea experienced an outbreak of vaccine-based polio infections in 2018, 18 years after the country was declared free from the disease.

So far, there is no evidence that the recent cases indicate an uncontrolled spread of the virus, at least in the US, Britain and India, experts say. In Kolkata, researchers surveyed all the neighborhoods near where traces of the virus had been found, to make sure no one might have been infected with polio.

The fact that health authorities have been able to detect cases – and traces in the sewage – points to the strength of surveillance systems in these countries. “It’s reassuring to me,” said Raman Bhatia, a veteran polio vaccine campaigner in India, associated with Rotary International, the US nonprofit that is one of the pillars of the global polio immunization efforts.

But like vaccination levels, regular checkups for polio-related paralysis cases have also declined over the past two years. In Indonesia, researchers found that such surveillance was severely disrupted during the pandemic.

That’s bad news, said Luthfi Azizatunnisa, a public health researcher at Yogyakarta-based Universitas Gadjah Mada, and lead author of the Indonesian study. The country has pockets of low vaccination coverage, she says. “If surveillance is disrupted, we will never know or may miss the polio virus circulating in the environment or community.”

Overall, the global polio burden of the wild virus has fallen by 99% since 1988, when the disease was endemic in more than 125 countries and infected 350,000 people a year. Today, those countries have shrunk to just two: Pakistan and Afghanistan.

The spate of cases of polio from vaccines has reopened debate among some experts about the benefits of the two main types of immunization commonly used against the disease.

The first, known as the IPV, uses an inactivated virus and is injected. The other, given orally, is known as the OPV and carries an attenuated but active virus that, after circulating in a population, can mutate and sometimes lead to outbreaks.

“Countries using exclusive IPV are not at risk of generating new circulating vaccine-derived polioviruses,” said Walter Orenstein, former director of the US National Immunization Program. For this reason, western countries are almost completely dependent on IPVs. But they too could inadvertently import vaccine-derived polio from countries where the OPV is used, he says.

A child is vaccinated against polio and diphtheria in Banda Aceh, Indonesia.
A child is vaccinated against polio and diphtheria in Banda Aceh, Indonesia. According to the WHO, global immunization and vaccination programs prevent two to three million deaths every year. Photo: Hotli Simanjuntak/EPA

Drops are easier to administer than injections because they don’t require qualified medical professionals, said Jay Wenger, director of the polio team at the Bill & Melinda Gates Foundation. The OPV is also more powerful than the IPV in reducing oral and fecal transmission of poliovirus, according to Steven Wassilak, associate chief for science at the Global Immunization Division of the U.S. Centers for Disease Control and Prevention (CDC) . “The OPV makes sense in those developing countries where sanitation is a challenge,” he says.

John is not convinced: In a letter published in July in the medical journal Lancet, he questioned the evidence behind the idea that the virus spreads mainly through oral or fecal routes in poorer countries.

What is clear is that like the wild virus, vaccine-derived polio seeks out victims among the unvaccinated. Those who have already received their doses are usually immune to the vaccine-derived virus, if they encounter it in the air or in the water.

“The primary risk factor of any polio virus – be it a wild virus or a vaccine – is low vaccination coverage,” said Zubair Wadood, a Geneva epidemiologist at the WHO. “If a population is fully vaccinated, it will be protected against any kind of polio virus.”

The threat increases if vaccination rates fall below 80%, says John Ross, assistant professor of medicine at Harvard Medical School. That creates an opening for “vaccine-derived poliovirus to circulate, increasing the risk of it reverting to a virulent form,” he says.

Indonesia, which uses a combination of the OPV and IPV vaccines, could be particularly vulnerable, Azizatunnisa said. According to the WHO and Unicef, the polio vaccination rate in the country has fallen to 68% by 2021. India also largely relies on the OPV, although the vaccination rate has not fallen below 80%.

A health worker walks through a narrow street full of sewage with a medical kit.
A health worker walks through a narrow street full of sewage as she approaches a house to administer a polio vaccination, Lahore, Pakistan, 2020. Photo: KM Chaudary/AP

Disinformation and conspiracy theories reached new heights during the pandemic, also impacting rates, Wassilak says. “Today, that’s a challenge we have to face to bring immunization levels back up.”

Rich countries should not leave their poorer neighbors alone to tackle the decline in vaccination rates, but donor countries and agencies should increase their support for the Global Polio Eradication Initiative, a public-private alliance including the Gates Foundation, the CDC , the WHO, step up. , says Unicef, Rotary International and Gavi, the vaccine alliance, Wenger says.

For health veterans like Orenstein, it’s a wake-up call. “We are still at risk,” he says. For patients like Ghai, the consequences of slipping against the debilitating disease are more personal.

“My parents taught me never to give up,” says the Delhi professor. “I didn’t let polio beat me. Neither should the world.”

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