Are we facing a selfish vaccine epidemic? Vaccination against Covid-19 is advancing at an unprecedented speed and five billion doses have already been administered on the planet. However, the distribution of these vaccines is still very uneven: while the vaccination rate in high-income countries is 111 doses per 100 population, it is only 2.4 doses per 100 population in low-income countries. A situation that is likely to worsen if other countries follow the decision of Israel and the United States to give a third dose to a large part of their population. However, this vaccine nationalism aimed at protecting the population of rich countries from the delta variant could be a very bad calculation in the long run. According to a study published on August 17, 2021 in ScienceAnd This may lead to the emergence of vaccine-resistant variants in the rest of the planet, which will eventually reach these highly vaccinated countries, rendering their vaccination efforts futile.

Choice pressure in infected persons

This study modeled the evolution of a pandemic according to vaccine sharing, showing that allowing the virus to spread at high levels in poorly vaccinated countries poses a very real risk for variants to emerge. “When we get infected, the virus multiplies in our body and it can happenRe Errors, creating mutations. When you are not immune to the virus, that is, you have not been infected before and you have also not been vaccinated, there is no reason to choose these mutations, because there is no selection pressure. to me the other sideIf you have very good immunity thanks to a vaccination or a recent infection, the virus will be quickly controlled and cannot mutate further. But in the midst of these two situations, when you have partial immunity due to a less recent infection or incomplete vaccination, that immunity will not prevent the virus from mutating and the virus will have a real advantage in developing resistance against this immunity. There, due to this selection pressure, resistant variants can appear, explanation for Science and the future Caroline Wagner, first author of the study. And immunity from vaccination is likely to last longer than after infection, so the greatest risk is mainly in people who are infected but not vaccinated.”

According to the authors, many of the countries most affected by the epidemic are very poorly immunized, such as Peru or South Africa. This creates an ideal situation for variants to emerge, in which many people have partial immunity to the virus. If the epidemic starts again at high levels and these people are infected again, the selection pressure in this population would be sufficient incentive to generate immune-resistant variants, and thus vaccines.

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