When she was eight years old, Anita Ghai was buried up to her neck in a mud grave during a solar eclipse, while her mother was pressured to chant verses from Hindu scriptures, ostensibly to cure Ghai of polio, which she had contracted at the age of two “I still have guilt, for what my mother had to endure because of me,” says Ghai, now 67 and dean of Delhi’s Ambedkar University.
Those nightmares, Ghai thought, were over when in March 2014 the World Health Organization declared India, home to half the world’s polio cases in 2009, free of the disease. However, eight years later, a disturbing sequence of events is occurring around the world. Pakistan has witnessed a spate of new cases, ending a 15-month period without a new case of polio. The wild virus from Pakistan has caused infections in Mozambique and Malawi, previously free of the disease.
In June, WHO reported cases of vaccine-derived polio, where a weakened virus from the vaccine itself spreads in the environment and infects people, in Eritrea, Ghana, Togo, Ivory Coast, Israel, Yemen , Nigeria and the Democratic Republic of the Congo. And in July, a patient in a New York City suburb was diagnosed with vaccine-derived polio. Traces of this form of the virus have also been found in sewage samples in Calcutta and London over the past six weeks.
Health workers with a box of polio vaccines at a railway station in Kolkata, India. Photo: Piyal Adhikary/EPA
These seemingly unconnected cases highlight a common threat: Globally, polio vaccination levels in 2021 fell to their lowest level in 15 years, according to WHO data, with immunization initiatives halted during covid India and Indonesia, two of the world’s most populous nations, have seen particularly steep declines in vaccine coverage.
That makes the recent wave of cases a canary in a coal mine, experts say, warning that the crippling disease eliminated in most of the world could return, especially in densely populated regions, unless countries redouble their efforts in vaccinations and surveillance.
“It was pretty scary,” says virologist T Jacob John, one of the founders of India’s polio vaccination program, of the trace of the virus found in Calcutta’s sewers. “A few more cases like this and we could be looking at an outbreak.”
It’s not just a hypothetical scenario: In 2018, Papua New Guinea experienced an outbreak of vaccine-derived polio infections, 18 years after the country was declared free of the disease.
So far, there is no evidence that the recent cases represent an uncontrolled spread of the virus, at least in the United States, Britain and India, experts say. In Calcutta, researchers surveyed every neighborhood near where traces of the virus had been found, to make sure no one was potentially infected with polio.
That the health authorities have been able to detect cases – and traces in the waste water – points to the strength of the surveillance systems in these countries. “It’s reassuring to me,” says Raman Bhatia, a veteran Indian polio vaccine activist associated with Rotary International, the US nonprofit that is a pillar of global immunization efforts. against poliomyelitis.
But like vaccination levels, periodic checks of polio-related paralysis cases have also fallen over the past two years. In Indonesia, researchers found that such surveillance was severely disrupted during the pandemic.
That’s bad news, says Luthfi Azizatunnisa, a public health researcher at Yogyakarta-based Universitas Gadjah Mada and lead author of the Indonesian study. The country has pockets with low immunization coverage, he says. “When surveillance is interrupted, we’ll never know or miss poliovirus circulating in the environment or community.”
Overall, the global burden of wild poliomyelitis has fallen by 99% since 1988, when the disease was endemic in more than 125 countries and infected 350,000 people a year. Today, these countries have been reduced to just two: Pakistan and Afghanistan.
The main risk factor for any poliovirus, whether wild or vaccine-derived, is low vaccination coverage Zubair Wadood, WHO
The rise in vaccine-related polio cases 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 IPV, uses an inactivated virus and is injected. The other, administered orally, is known as OPV and carries a weakened but active virus that, after circulating in a population, can mutate and cause outbreaks.
“Nations using exclusive IPV are not at risk of generating new circulating vaccine-derived polioviruses,” says Walter Orenstein, former director of the US National Immunization Program. For this reason, Western nations are almost entirely dependent on IPV. But they, too, could accidentally import vaccine-derived polio from countries where OPV is used, he says.
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 each year. Photo: Hotli Simanjuntak/EPA
The drops are easier to administer than injections because they don’t require trained medical professionals, says Jay Wenger, director of the polio team at the Bill & Melinda Gates Foundation. OPV is also more potent than IPV at stopping oral and fecal transmission of the polio virus, according to Steven Wassilak, chief science associate at the Centers for Disease Control and Prevention’s Global Division of Immunization. the US Centers for Disease Control (CDC). “OPV makes sense in those developing countries where sanitation is a challenge,” he says.
John is not convinced: In a letter published in the Lancet medical journal in July, he questioned the evidence behind the idea that the virus is predominantly spread by oral or faecal routes in poorer countries.
What is clear is that like the wild virus, vaccine-derived poliomyelitis seeks victims among the unvaccinated. Those who have received all doses are mostly immune to the virus derived from the vaccine, if they find it in the air or water.
“The main risk factor for any poliovirus, whether wild or vaccine-derived, is low vaccination coverage,” says Geneva-based WHO epidemiologist Zubair Wadood. “If a population is fully vaccinated, it will be protected from any form of poliovirus.”
The threat increases if vaccination levels fall below 80 percent, says John Ross, an assistant professor of medicine at Harvard Medical School. This creates an opening for the “vaccine-derived poliovirus to circulate, increasing the risk that it will revert to a virulent form,” he says.
Indonesia, which uses a combination of the OPV and IPV vaccines, could be particularly vulnerable, Azizatunnisa suggests. The country’s polio vaccination rates plummeted to 68% in 2021, according to the WHO and Unicef. India is also mostly dependent on OPV, although vaccination rates have not fallen below 80%.
A health worker walks through a narrow street filled with sewage as she approaches a house to administer a polio vaccine, Lahore, Pakistan, 2020. Photo: KM Chaudary/AP
Misinformation and conspiracy theories reached new heights amid the pandemic, affecting rates as well, Wassilak says. “Today, this is a challenge we must face to raise immunization levels again.”
Rich nations should not leave their poorer neighbors to deal with declining vaccination rates alone, but donor nations and agencies must step up their support for the Global Polio Eradication Initiative, a public-private alliance that includes the Gates Foundation, the CDC, the WHO. , Unicef, Rotary International and Gavi, the vaccine alliance, says Wenger.
For healthcare veterans like Orenstein, it’s a wake-up call. “We’re still at risk,” he says. For patients like Ghai, the consequences of slipping up against the debilitating disease are more personal.
“My parents taught me to never give up,” says the teacher from Delhi. “I haven’t let polio defeat me. The world shouldn’t either.”
Sign up for a different view with our global dispatch newsletter – a round-up of our top stories from around the world, recommended reading and our team’s thoughts on key development and human rights issues, which delivered to your inbox every two weeks:
Register for Global Dispatch: Please check your spam folder for the confirmation email