Indian scientists have published the results of the study
Indian scientists from the National Institute of Virology in Pune, with the support of the country’s Ministry of Health and the Department of Health Research, have carried out scientific work on the study of new strains of SARS-CoV-2 and concluded that the recently appeared variant P.2, first discovered in Brazil, possesses increased pathogenicity, that is, it causes a more severe course of COVID-19. True, so far this has been proven only in laboratory hamsters.
During the year of the COVID-19 pandemic, the SARS-CoV-2 virus has accumulated serious mutations that have led to the emergence of new strains. The first alarming variant B.1.1.7 was identified at the end of December in the UK and has now spread to 62 countries in Europe, Asia, the United States, etc. Today, this variant has about 17 mutations.
The next dangerous variant (B.1.351) appeared in South Africa (today it has 21 mutations). He already travels to Africa, Europe, Asia and Australia.
In January, the P.1 lineage appeared, which is of greatest concern today (17 mutations). This variant was widespread in the state of Amazonas in Brazil, and also noted in the Faroe Islands, South Korea and the United States. So far, the least known about it, including how contagious it is and whether it causes a more severe course of the disease. However, it is he who is blamed by some experts for the outbreak of re-infections in the Brazilian city of Manaus, where it would seem that herd immunity had already been achieved (by the time he arrived, 70% of the inhabitants had been ill there). In addition, Brazil reported on another version of the line – P.2.
Today, public health experts around the world are closely monitoring the three most proliferating variants of SARS-CoV-2: British, South African and Brazilian. They not only have an increased ability to infect, but are also able to bypass the immune defenses after previous strains, which jeopardizes the effectiveness of vaccination. However, there was still no scientific data about the P.1 and P.2 lines: no one has yet evaluated their properties in laboratory conditions.
However, the Brazilian Ministry of Health and local doctors after the spread of P.1 and P.2 reported a much more severe course of the disease. The Brazilian strain P.1 attracted the main attention, which largely displaced P.2 in Brazil and spread to many countries of the world. P.2, which is losing competition to other dangerous strains, is unlikely to spread particularly widely. The discovery by Indian scientists at the same time reveals a possible close prospect of the virus changing its virulence if P.2 mutations appear in the next generation of strains.
Indian scientists tried to evaluate the pathogenicity of variants of the SARS-CoV-2 virus in animal models. 9 Syrian hamsters (these animals have already been used to assess the pathogenicity of other variants of the coronavirus) were artificially infected with the usual variant of the virus, and another 9 with variant P.2, which was obtained from two international travelers who returned to India from Britain and Brazil. The hamsters were monitored for a week. As a result, it was found that P.2 causes more weight loss, carries a higher viral load in the respiratory tract, and also remained active for longer in the lungs. In hamsters infected with the common variant of the virus, lung damage was mild, in those infected with P.2 it was severe, with a specific pattern of damage, including hemorrhages in the lung tissue.
P.2 becomes the first variant with an experimentally proven higher pathogenicity. Experiments with other dangerous strains have not shown an increase in pathogenicity. B.1.1.7 and B.1.617.2 are associated with a more severe course of the disease, probably due to inoculation with large doses of the virus, since dangerous strains create a higher viral load in the upper respiratory tract. The combination of high viral load with increased pathogenicity makes Brazil P.2 especially dangerous. In addition, experiments have shown that the P.2 line is twice as resistant to two docks of anti-coronavirus vaccine compared to older strains.
The authors of the study call for increased genomic surveillance of the spread of new Brazilian strains, which, fortunately, are so far rarely detected. “It will also allow us to quickly assess their prevalence around the world. With the efficacy of existing COVID-19 vaccines against new strains is not yet known, we still need to continue to monitor non-drug measures such as the use of masks, physical distancing, hand hygiene and avoidance of public gatherings to prevent the transmission of these new variants to to a large extent, ”the authors of the work note.
Meanwhile, as the well-known virologist, corresponding member of the Russian Academy of Sciences Alexander Lukashev told “MK”, to date there is no convincing scientific evidence that the Brazilian strain is more pathogenic for humans, that is, it often causes a serious disease: “Data on greater pathogenicity for laboratory animals deserve attention, but the pathogenicity of the virus for different hosts does not always correlate. But it is less neutralized by the antibodies of those who have been ill and vaccinated – about like the British one – and is less neutralized by the antibodies of those who have been ill and vaccinated. We do not know exactly how much the risk of getting sick for these people increases. In general, they remain protected, but the risk of getting sick again, especially in a mild form, has become noticeably higher. “
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The most dangerous strain in the world
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