Polio in Gaza: Experts explain the outbreak and the public health response
October 3, 2024 – In August, a confirmed case of polio was reported in Gaza—the first in 25 years—which created significant concern for further spread. The Palestine Program for Health and Human Rights convened a discussion on September 24 to examine the causes of the outbreak and the public health response.
Below are excerpts from the discussion and thoughts from the panel’s moderator, lightly edited for clarity.
Amir Mohareb, an infectious disease doctor at Massachusetts General Hospital and an assistant professor at Harvard Medical School:
There are two types of polio vaccines. One is an intramuscular shot, which is very safe and effective, but is not as practical in an outbreak setting—particularly in low-resource environments. Thankfully, we also have the oral polio vaccine. This is the one that’s used in the majority of low-income countries around the world. The oral polio vaccine is a live, attenuated vaccine, meaning it uses a weak form of the actual virus to induce immunity.
The oral vaccine is also very safe and effective, and much more affordable and easier to distribute. However, it has a very rare downside: when the weakened form of the virus gets shed in the stool of vaccinated people and begins to circulate, in rare cases it can form a genetic mutation that reverts to a virus that can cause paralysis, like the wild-type virus.
This can lead to vaccine-derived polio, which has caused outbreaks around the world—and now, we are seeing this risk become reality in Gaza.
Sam Rose, the senior deputy director of the United Nations Relief and Works Agency (UNRWA) Affairs in Gaza.
In July, traces of polio were detected in Gaza’s wastewater. In my view, that is directly related to the ongoing conflict’s decimation of both the health care sector and the waste management and sewage infrastructure, combined with the fact that 90% of the population is displaced. These conditions raised the risk of infectious disease.
In August, a 10-month-old boy suffering from partial paralysis was confirmed to have polio, which activated a vaccination campaign by UNRWA, the World Health Organization, local health authorities, and other partners. We had a target of vaccinating 640,000 children, or 90% of all children under 10 in the region.
I’ve been on the ground for these campaigns, which took place during agreed-upon pauses in fighting. However, these pauses did not cover the entire geographical area. In addition, northern Gaza has been cut off since October of last year, making the campaign challenging in that region.
At the end of the first vaccination round, about 560,000 children had been vaccinated—below the target, but still a successful effort given the massive complexity facing Gazans amidst a conflict that has harmed infrastructure, logistics, and communications as well as general safety. Additionally, our surveys showed polio vaccine coverage exceeded 90%, the goal to interrupt transmission, suggesting that we may have overestimated the number of children under 10 years. Before the current conflict in Gaza, polio vaccination coverage exceeded approximately 99%.
Guy Shalev, executive director of Physicians for Human Rights Israel and a research fellow at the Minerva Center for the Rule of Law Under Extreme Conditions
The very impressive international campaigns unfolding right now are up against serious challenges, including an attack on the Gazan healthcare system that is more damaging and of a greater scale than we’ve seen in any other recent global conflict.
But the challenges aren’t new; they should be viewed in context. The COVID-19 vaccine is a strong example. We at PHRI appealed to the High Court of Justice in Israel in March 2021 to force the Israeli government to fulfill its responsibility to provide vaccinations in the West Bank and Gaza. At that time, almost 6 million Israeli citizens were already vaccinated against COVID, compared to only a few thousand vaccinated in the West Bank and Gaza.
So we must acknowledge that, even as we continue to hope for a ceasefire, the social determinants of health and infrastructure in Gaza are still issues that will concern us for many years going forward.
Mary Bassett, director of the François-Xavier Bagnoud (FXB) Center for Health and Human Rights and FXB Professor of the Practice of Health and Human Rights in the Department of Social and Behavioral Sciences at Harvard T.H. Chan School of Public Health
In July of 2022, I was the New York State health commissioner when a young adult with paralysis was diagnosed with polio.
While poliovirus was eliminated from the United States in 1979, the disease did continue to be diagnosed from time to time in people who had been infected outside the U.S. This case was different because the patient— who was unvaccinated—had been infected by a vaccine-derived poliovirus circulating within the U.S. We believe that low vaccination rates in some U.S. communities gave the virus a foothold.
After the diagnosis, there was tremendous shock in New York and around the country. But there should be no shock to see polio in Gaza today. The region is a perfect storm for a polio outbreak that was completely preventable and poses a threat to the whole region, especially for the under-vaccinated and unvaccinated.
It’s also important to note that we are likely seeing just the tip of the iceberg. An estimated 70% of polio infections are asymptomatic. Symptomatic infections most commonly result in flu-like symptoms. Fewer than 1% of infected individuals develop irreversible, paralytic disease. So, when you see one case of paralytic polio, many more people are likely to be infected.
Achieving necessary levels of vaccination coverage in Gaza will require a massive effort. Israeli pediatrician Dorit Nitzan, director of the master’s program in emergency medicine at Ben-Gurion University and former regional emergency director for the World Health Organization’s European office, offered this appraisal: “The prescription is ceasefire, vaccines, and good public health conditions.”
Photo: Anas Mohammed / Shutterstock
