Variant Omicron two-dose hole Pfizer, the study

Against the Omicron variant of the coronavirus, the neutralization capacity of the two doses of Pfizer / BioNTech anti Covid vaccine with mRna is compromised, but the booster dose restores “a powerful neutralizing activity”. The new mutant also shows significant “resistance to various monoclonal antibodies in clinical use”. This is what emerges from a study conducted by the University of Cologne with other German universities, subjected to peer-review and accepted for publication in ‘Nature Medicine’. Read also The work immediately made available in a pre-printed version reports the results of the tests conducted by the authors who wanted to explore the potential for immune evasion that characterizes the variant. The sera of vaccinates and convalescents were probed, and the activity of monoclonals was also evaluated. Scientists report an “almost complete lack of neutralizing activity against Omicron in the sera of the vaccinated and convalescent”. However, they add, “boosters of the mRna vaccine” in both cases “resulted in a significant increase in neutralization activity against Omicron. The study therefore demonstrates that boosters may be critical to the humoral immune response” to the mutant. The analysis was done 5 months after the primary vaccination course and one month after the booster. After 2 doses of Pfizer / BioNTech vaccine, neutralizing activity against the parent virus had decreased 4-fold over the 5-month period (from 546 to 139) and strongly increased with booster. Against Omicron “only 30-37% of the samples showed detectable neutralization”. However, the neutralizing activity for Omicron increased more than 100 times after the booster dose (reaching 1,195 in the indicator used to measure it), and was detectable in all 30 participants analyzed (100%). This serum neutralization activity against Omicron following booster immunization was “even higher than the neutralizing titers” obtained against the native Wu01 virus after 2 doses. As for the recovered, immediately after infection, the neutralizing activity against the original virus was variable from 37 to 11,008, (the value calculated by the scientists was 494 and decreased to 93 after 12 months). After a single dose of the vaccine there was a strong increase in neutralizing activity (7,997 versus Wu01). No neutralization or only weak response against Omicron at a median of 12 months after Sars-CoV-2 infection, but one dose of vaccine induced a large increase in response (8 to 1,549 one month after injection) As for monoclonals, neutralizing activity against the Omicron variant was abolished in 7 out of 9 antibodies. And this, the authors conclude, “may limit treatment options for Omicron-induced Covid-19”.