I’d like to talk about a couple of challenges to polio eradication that we still need to manage on this journey to zero polio: exported cases of wild polio and circulating vaccine-derived poliovirus (cVDPV2).
On May 18, 2022, health authorities in Mozambique confirmed that a child had contracted wild poliovirus type 1. The child had first experienced paralysis in March of 2022. This case in Mozambique followed an earlier case of wild poliovirus type 1 in a child in Malawi in mid-February 2022. The virus in both cases were gene sequenced and were found to be linked genetically to a polio strain that was circulating in Pakistan. Because these cases were imported from Pakistan, they do not represent a change in Africa’s polio-free status. Mozambique and Malawi, along with Tanzania, Zambia, and Zimbabwe have increased their ongoing vaccination campaigns in response to these cases.1
People regularly move across borders in this region and these cases demonstrate the potential for outbreaks beyond Afghanistan and Pakistan, where wild poliovirus remains endemic. The potential for polio outbreaks to erupt beyond Afghanistan and Pakistan is very real and we need to continue the aggressive push to eradicate this disease from our world.
Circulating vaccine-derived poliovirus (cVDPV) is a challenge to the overall eradication of polio. In under-immunized populations, the live, but weakened virus that is contained in the oral polio vaccine can circulate within the population. If an unvaccinated person comes into contact with the stool or respiratory secretions of an individual who is infected, that unvaccinated person may contract cVDPV. Every time a virus replicates itself, the opportunity for mutations in that virus is present. If these strains circulate for an extended period of time in these under-immunized populations, more mutations can occur and eventually these mutations can result in a form that causes paralysis. This is cVDPV.2 There are three types of cVDPV (Types 1, 2, and 3), with Type 2 causing the overwhelming majority of cases.
Thankfully, the incidence of cVDPV is relatively rare as compared to the billions of doses of oral polio vaccine administered each year. In 2021, a total of 688 cases of cVDPV were confirmed worldwide and in 2022, as of May 24, there were a total of 68 cases worldwide, according to the World Health Organization.3 While cVDPV is still rare, its existence provides an opportunity for the polio virus to spread and mutate within those under-immunized populations. Until not only wild poliovirus, but also cVDPV, are eradicated, the world must continue to aggressively immunize our children until this scourge has been completely eliminated from the earth.
How Can I Help Eradicate Polio?
Rotarians can donate to End Polio Now online at https://www.endpolio.org/donate
Every dollar donated through End Polio Now will be matched by two dollars from the Bill and Melinda Gates foundation, tripling your financial impact!
Notable Person Stricken With Polio: Alan Alda (b. 1936); Actor in many television and film roles but most famous for his portrayal of Dr. Hawkeye Pierce in M*A*S*H. “I got it when I was 7. I had a stuffy nose at the Warner's movie theater — honking the whole evening. I couldn't clear my nose. When I got home, I threw up, and my legs were unsteady. The next day, I had a stiff neck. I couldn't sit up in bed. My parents called the doctor. Went to the hospital, had a spinal tap. I was in the hospital for two weeks, but then I had about six months of a therapy devised by Elizabeth Kenny, the famous nurse from Australia. I had nearly scalding blankets wrapped around my limbs every hour. It was hard on me. It was harder, I think, on my parents, who couldn't afford a nurse and had to torture me themselves. It's always better to pay somebody to torture your kid.”4
A health worker administers the oral polio vaccine to a young girl as other children wait for
their turn at a school in Karachi, Pakistan, where a case of wild polio was reported for the first
time in 15 months in April. © Rizwan Tabassum /AFP via Getty Images
their turn at a school in Karachi, Pakistan, where a case of wild polio was reported for the first
time in 15 months in April. © Rizwan Tabassum /AFP via Getty Images
References: