An outbreak of poliomyelitis in Africa is linked to the use of live vaccines, the Associated Press reported on March 17.
The East African nation of Burundi is experiencing its first outbreak of polio in 30 years.
The World Health Organization (WHO) said there were eight cases of the illness, and five samples taken from wastewater showed the presence of poliovirus type 2.
“Circulating poliovirus type 2 is the most prevalent form of polio in Africa and outbreaks of this type of poliovirus are the highest reported in the region, with more than 400 cases reported in 14 countries in 2022,” stated the WHO. “Circulating poliovirus type 2 infection can occur when the weakened strain of the virus contained in the oral polio vaccine circulates among under-immunized populations for long periods.”
Live Oral Vaccines Used
Unlike the dead-virus vaccines administered in developed nations, oral polio vaccines use a live attenuated virus and are generally distributed to developing nations because they are cheaper, do not require refrigeration, and are easier to administer.
Viruses in live attenuated vaccines occasionally regain full virulence in vaccinated subjects who can transmit the illness to others. The vaccine-derived poliovirus (cVDPV), can spread by viral shedding and through wastewater from the stool of vaccinated children.
There have been multiple outbreaks of cVDPV across Africa in recent years, and Pakistan and Afghanistan now report more cases of paralysis from vaccine-derived viruses than from the wild virus.
There is a strong push for polio vaccines on the continent, Matshidiso Rebecca Moeti, WHO Regional Director for Africa, told UN News, a United Nations agency.
“Polio is highly infectious and timely action is critical in protecting children through effective vaccination,” said Moeti. “We are supporting the national efforts to ramp up polio vaccination to ensure that no child is missed and faces no risk of polio’s debilitating impact.”
Polio Eradication Campaign
Eliminating the disease globally is the goal of the vaccination programs that are introducing vaccine-derived variants into areas free of the wild variant, says Martin Kulldorff, a Swedish biostatistician, former professor of medicine at Harvard Medical School, and a fellow at The Academy for Science and Freedom at Hillsdale College.
“The goal is to eradicate polio worldwide, and until it has been, polio vaccinations should continue,” said Kulldorff. “If not, the disease will reappear.”
The oral vaccine has additional health benefits, says Kulldorff.
“The live vaccine also has nonspecific effects, protecting children against other infectious diseases (see research by Dr. Christine Stabell Benn),” said Kulldorff. “That is especially important in the developing world where children commonly die from other infectious diseases.”
Polio Severity Age-Related
Widespread use of live attenuated vaccines isn’t the safest path to the eradication of polio, says Jane Orient, M.D., executive director of the Association of American Physicians and Surgeons and president of Doctors for Disaster Preparedness.
“We know full well that the live vaccine can cause paralytic polio, both in people who receive it and (in) their contacts,” said Orient. “Very young children tolerate polio very well—just a mild illness that makes them immune. It is the older contacts who are severely hurt. Therefore, only killed vaccine is used in the United States. Oral live vaccine is used deliberately in Africa, Pakistan, etc.”
‘Collateral Damage Doesn’t Count’
It is important to understand what the underlying motives might be for a vaccine campaign when a disease like polio has been under the radar for decades, says Orient.
“There is the desire to claim credit for eradicating a disease through universal vaccination… or something more sinister,” said Orient. “Note that even where polio is supposedly gone, there is acute flaccid myelitis, which clinically looks like polio and may also be caused by a (presumably different) enterovirus.”
In any case, agencies supporting oral polio vaccines are minimizing the outbreak.
“While detection of these outbreaks is a tragedy for the families and communities affected, it is not unexpected with wider use of the vaccine,” the Global Polio Eradication Initiative stated on its website.
This seeming indifference to the outbreak is contrary to medical ethics, says Orient.
“It’s a product of substituting public health for medicine,” said Orient. “The collateral damage doesn’t count, especially if it is mostly in Africa or Pakistan. Is that not outrageous? I read somewhere, maybe in Science or Nature, that parents were assaulting vaccinators, even when they had police escorts.”
Is Total Eradication Possible?
In the United States, where the last previous transmission of the disease was recorded in 1979, a case was detected in Rockland County, New York in the summer of 2022.
The case was linked to the oral vaccine-derived strain. The virus also turned up in New York City wastewater, according to the city’s Department of Health and Mental Hygiene in August, after it was detected in Orange County and Rockland County, north of the city, in May, June, and July.
Vaccine-derived rogue variants from Pakistan and Afghanistan turned up in sub-Saharan Africa, Yemen, Malaysia, and the Philippines in 2020. So, while the wild variant may be in retreat, the vaccine-derived variant is proliferating.
Kevin Stone (firstname.lastname@example.org) writes from Arlington, Texas.
Image courtesy of wiki commons.