At the end of August, the World Health Organization announced that wild poliovirus (WPV), the pathogen responsible for polio, had been eradicated from Africa after four consecutive years without a declared case. A few days later, however, thirteen cases were reported in Sudan. According to some publications on social networks, it is the vaccine itself that is responsible for these new cases. Technically, this is quite true, but the anti-vaccine sites fail to specify that this same vaccine has reduced the number of polio cases by more than 99%. Explanations.
What these posts say:
“While international organizations like the World Health Organization (WHO) regularly brag about supposedly eradicating polio with vaccines, it seems the opposite is happening. (…) because many children are paralyzed by a deadly strain of the pathogen derived from an active vaccine ”, advances a text reproduced on many sites such as Guyboulianne, Aubedigitale or Wikistrike, who thinks it is “One of the biggest scandals in public health”.
IT’S MORE COMPLICATED
- Wild strain and vaccine strain
On August 25, WHO announced eradication of strain polio “Wild” from the African continent, concluding: “With this historic milestone, five of the six WHO regions – representing over 90% of the world’s population – are now wild poliovirus free, bringing the world one step closer to global polio eradication. » The information has been taken up by many news sites which sometimes have failed to specify as derivatives of vaccine strain of the disease continue to circulate in Africa.
In the communicated cited by the publication, the WHO explains that cases of polio contracted because of type 2 virus derived from a vaccine strain (cVDPV2) were detected on August 9 in Sudan. The country’s health authorities have notably reported two cases of acute paralysis in very young children who have been vaccinated.
- What is a vaccine strain of polio?
“These strains [vaccinales] sometimes emerge in areas where the population is not very well immunized, due to the use of oral vaccine (OPV). It’s very rare, but it happens ”, explain to World Oliver Rosenbauer, Polio Eradication Program Spokesperson for WHO.
The disease was widespread all over the world, until a vaccine was discovered in the 1950s
Polio is a highly contagious infectious disease, which mainly affects children under 5 years old. It is caused by the poliovirus, which invades the nervous system and can cause irreversible paralysis. There is no treatment and between 5% and 10% of paralyzed patients die from it. The disease was prevalent all over the world until a vaccine was discovered in the 1950s. There are currently two types of vaccines:
– the injectable inactivated polio vaccine (IPV) requires multiple injections and regular boosters. This is why its cost has long limited its distribution to certain developed countries, such as France;
– the oral polio vaccine (OPV), less expensive, has the particularity of being administered without injection and interrupts person-to-person transmission, “Which explains why it has until now been the preferred tool of the eradication program”, highlighted the Pasteur Institute.
OPV contains an attenuated form of poliovirus which replicates in the intestine of the vaccinated child for a limited period of time, and helps to develop immunity, Explain WHO. In areas with poor sanitation, these weakened vaccine viruses can spread once excreted and thus protect other children through “Passive immunity”, before turning off.
However, these weakened viruses can also continue to circulate and spinning in very rare cases, when populations have very low immunity: “The virus acquires, by mutation, the capacity to cause paralysis” then becoming what is called a “Circulating poliovirus derived from a vaccine strain (cVDPV)”, specifies the WHO. This is the case of the virus detected on August 9 in Sudan. For the year 2019, 195 cases of viruses linked to derived strains were thus notified according to the organization data.
This risk is however very limited, and does not come from the vaccine itself, because a population with a “Good vaccination coverage” is protected against both wild polioviruses and those derived from vaccine strains, says Oliver Rosenbauer. This is what he calls the “OPV paradox” : “The only way to stop this strain is to carry out an OPV vaccination campaign”.
- 99% fewer polio cases since 1988
These cases of virus mutations are not new. “The first time we observed strains derived from the vaccine was in 1999, on the island of Hispaniola”, explains Rosenbauer, who specifies that there have been “Many outbreaks since”.
This led the WHO to publish in 2002 a document in which it evokes a risk “In one case for about three million doses – that the OPV causes paralysis either in the vaccinated child or in a close contact”. The WHO does not therefore seek to ignore these contaminations linked to post-vaccine mutations, contrary to what the text disseminated on social networks suggests.
Furthermore, it is misleading to say that OPV is a major vector of the epidemic, because it is precisely this vaccine that has largely contributed to reducing the number of polio cases. more than 99% since 1988. “Before, there were 50,000 children paralyzed in Africa every year from wild poliovirus and no one asked about two hundred cases due to derived strains, but since today there is no wild poliovirus, the only children we see paralyzed are from derived sources ”, explains the spokesperson for the eradication program.
The WHO assures that the OPV would have “allowed at least five million children to escape permanent paralysis”
WHO calls OPV a vaccine “Safe and effective” and ensures that he would have “Enabled at least five million children to escape permanent paralysis.” She adds polio poses a risk to children “Much higher” to that associated with the polio vaccine. However, Olivier Rosenbauer recognizes that these changes are problematic: “Our goal is to eradicate all polioviruses, but it’s a step-by-step process. You have to eliminate the wild strain first, because it’s the most dangerous, and the only way to do that is by using OPV. After that, we will have to stop using this vaccine ”, he believes.
WHO is banking on the development of a new, more genetically stable vaccine, nVPO2, to reduce the risk of mutations that can lead to paralysis. Two hundred million doses should be ready “By the end of 2020”, according to Global Polio Eradication Initiative (GPEI), a global body in charge of the fight against polio.
- A vaccine funded by Bill Gates?
In addition, the viral text ensures that “International health organizations have “accidentally” reintroduces the disease in Pakistan ” and “In Afghanistan” with its vaccine strains of the disease. This is wrong, because these two countries have never eradicated wild poliovirus in the first place.
Another statement: “The oral polio vaccine is distributed to the African population by (…) a consortium which is supported and funded by the Bill and Melinda Gates Foundation ”. This time it’s true: the Bill and Melinda Gates Foundation is indeed one of the contributors to GPEI. But this program is funded by many other organizations, like WHO, Unicef, the humanitarian organization Rotary International and several countries. Finally, it should be noted that the oral vaccine, OPV, has been used since 1964, while the Gates Foundation was not created until 2000.