In an interview with the “world”, the British epidemiologist and virologist Peter Markov warns against a bad perception of the evolution of Sars-Cov-2, whose exhaust possibilities towards the system immune is, according to him, “far from being exhausted”.
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Peter Markov is an epidemiologist and doctor of virology. He studied the evolution of the hepatitis C virus, in particular the influence of colonial history and transatlantic slavery on the selection of viral genotypes currently in circulation. He worked within the Health Protection Agency, the British Public Health Agency, then at the European Center for Disease Prevention and Control. He is now stationed at the Research Center joint, the European Union scientific and technical research center in Ispra (Italy). He recently co-signed, in the journal window Nature Reviews Microbiology , an article denouncing the myth according to which the Sars-Cov-2 virus would evolve towards a lesser virulence and alerting the risk of emergence of new variants.
in your article, You criticize the use of the concept of endemicity. Why?
This concept was mobilized for rhetorical purposes to proclaim the end of the pandemic and the lifting of barriers. However, endemicity means that the virus circulates chronically in the population, not that it is safe. The public health problem it poses depends both on the level of this circulation and the severity of the infection. An endemic virus has a very different impact if it infects 1 % or 10 % of the population. But even a low prevalence, some viruses pose a public health problem. This is the case with HIV or with the hepatitis C virus, whose infection can in particular lead to liver cancer.
you also denounce the idea that SARS-COV -2 would evolve towards a lesser virulence…
This is one of the persistent myths in virology. He starts from the postulate than the less a virus kills, the more he survives in the population. In reality, many viruses are transmitted intensely before killing their hosts, because the severe forms of the disease and death occur late in the infection process. This is the case for the SARS-COV-2 virus as for other viruses, such as the influenza virus or the HIV virus, for which several years separate the contagion from the occurrence of symptoms. And, as with all living entities, the selection pressure is exercised on the ability of the virus to reproduce, and therefore to be transmitted in the case of viruses.
As long as the population is virgin vis-à-vis the virus, transmission is favored by the increase in infectious power, hence the Alpha and Delta variants selected for this property at the start of the pandemic. On the other hand, once the virus has circulated in the population, collective immunity slows down its propagation and infectiousness makes the difference between the variants. To continue to circulate, the virus must lift this brake by escaping the immunity directed against the previous variants. Hence the advantage conferred on omicron by its exhaust mutations, which can reinfect people who have been by the previous variants. Severity is only a by-product of this evolution which is difficult to predict and the slightest severity of omicron does not presage that of the variants to come. Nothing excludes that they are more pathogenic.
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