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Covid-19: Vaccines protect against the BA.2 sub variant as much as they do against the Omicron variant

The BA.2 variant of SARs-CoV-2, the virus responsible for Covid-19, is in the process of He replaces his older brother, the Omicron variant (or BA.1), has been identified as the dominant form of the virus in many countries, raising fears of new epidemics. corn Study previously published on March 13 On medRxiv – not peer-reviewed – it shows mRNA vaccines from Pfizer-BioNTech or from Moderna offer a similar degree of protection against both strains – although protection against infection and against symptomatic forms of the disease declines in the months following the second or third dose.

It has been known for months that the Omicron variant largely escapes the protection conferred by mRNA vaccines against mild forms of Covid-19, and researchers soon realized that its BA.2 variant spreads more efficiently. But it is not yet clear whether this newcomer is more adept at evading vaccines.

“Is BA.2 worse than BA.1?” asks Laith Abu-Raddad, an epidemiologist at Weill Cornell Medical University, Qatar, and co-author of the new study. The researcher and colleagues analyzed vaccination and testing data in Qatar. They found that Qataris who received two doses of an RNA vaccine from Pfizer-BioNTech or Moderna were significantly protected for several months from Covid-19 symptoms caused by the BA.1 or BA.2 variants. But this protection drops to about 10% after only four to six months (in other words, vaccination prevents only 10% of cases that would have occurred if no one had been vaccinated).

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Protection against the BA.2 subvariable did not appear to decline more rapidly than protection against the Omicron variant, and the booster dose restored protection against symptomatic forms induced by any of the subvariants between 30 and 60%. Monitoring data collected in the UK reveal a similar trend: the efficacy of the RNA vaccine against Covid-19 episodic forms is less than 20% for the BA.1 and BA.2 sub variants twenty-five or more weeks after the second dose, but returns to about 70 % two to four weeks after a third dose.

Qatari researchers have also appreciated the protection afforded by RNA vaccines against severe forms. For this, however, they had to group the cases associated with the BA.1 and BA.2 subvariables together. In fact, the population of Qatar is young, severe cases of Covid-19 are rarely, and the results become statistically significant only by adding the cases of the two sub-variables.

This analysis showed protection against severe forms of 68% or more for at least seven months for people who received only two doses of the vaccine, and up to more than 80% after the booster dose. For Laith Abu-Raddad, since 70-80% of the cases pooled in the study were due to BA.2, this indicates that vaccines still provide a high level of protection against severe forms caused by the BA.2 variant.

promising results

According to virologist Andrew Pekosz of Johns Hopkins University in Baltimore, Maryland, “This study is very powerful. Qatar has been at the forefront of countries providing data on the efficacy of vaccines against COVID-19.”

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Laith Abu-Raddad says he is relieved that vaccines are continuing to prevent many of the most severe cases of Covid-19 in response to the new BA.2 variant. “They are actually doing remarkably well, given the challenges posed by the evolution of the virus.”

However, Andrew Pekosz believes the new findings underscore the importance of stimulant doses. “Focusing on a basic vaccination schedule is no longer sufficient. Plans are needed to vaccinate the population effectively with booster doses.”

Going forward, Laith Abu-Raddad believes that we should move away from designing vaccines against single variants and focus instead on vaccines that are effective against all strains of SARS-CoV-2.