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High titers of neutralizing antibodies against the omicron mutation are found in all individuals who have received three doses of mRNA vaccine or in those who recovered from COVID-19 and were subsequently vaccinated with mRNA vaccine
The recently emerged variant B.1.1.159 (omicron) of SARS-CoV-2 has a large number of mutations (n=32) in the spike protein compared to that of the original virus (Wuhan), particularly in the entry site of the virus into human cells, i.e. the primary target of neutralizing antibodies. Recent research just published in the prestigious international journal New England Journal of Medicine studied the titers of neutralising antibodies against Wuhan coronaviruses and the omicron mutant in 169 plasma samples from 47 individuals with differential exposure to viral antigens through infection, vaccination or both. Professors Evangelos Terpos (Hematologist) and Thanos Dimopoulos (Dean of the School of Medicine of the University of Athens) summarize the main points of the study.
In plasma samples taken approximately 1 month and 6 months after infection from individuals who had recovered from COVID-19, neutralizing antibody titer values ≥50% (considered protective against COVID-19 infection) were 58 and 32 times lower for omicron than those against the Wuhan strain, respectively.
In plasma samples from subjects who had received two doses of mRNA vaccine [BNT162B2 (PFIZER-BIONTECH) OR MRNA-1273 (MODERNA)] 1.3 months before sampling, neutralizing antibody values ≥50% were 127-fold lower for omicron than for the Wuhan strain. At 5 months after inoculation, the neutralizing power was 27-fold lower for omicron. Several plasma samples from recipients of Ad26.COV2.S single-dose vaccine (Johnson & Johnson), taken 1 or 5 months after vaccination, had no detectable neutralising activity against omicron.
It is worth noting, however, that vaccination of individuals who had recovered from Covid-19 or administration of a third dose of an mRNA vaccine to vaccinated individuals at least 6 months after the second dose of an mRNA vaccine resulted in a significant benefit in neutralizing activity against omicron. Specifically, after vaccination in subjects previously infected with SARS-CoV-2, neutralizing antibody values ≥50% were 238-fold and 154-fold greater for Wuhan and omicron subtypes, respectively, than the titers that subjects had after infection and before vaccination.
For those who had received two doses of an mRNA vaccine approximately 6 months earlier, and then received a third dose of an mRNA vaccine approximately 1 month before sampling, neutralizing antibody values ≥50% after the booster dose were 26-fold greater for the Wuhan strain and 38-fold greater for omicron. Neutralization titers against omicron were very high in all individuals who had recovered from COVID-19 and were subsequently vaccinated and in those who had received three doses of mRNA vaccine, but titers were low or undetectable in many unvaccinated individuals who had recovered from COVID-19 and in recipients of only two doses of mRNA vaccine.
Although these findings suggest that the omicron variant shows a significant degree of escape from neutralizing antibodies after COVID-19 infection or double vaccination with m-RNA vaccines, they also indicate that the booster dose of m-RNA vaccine in these groups (i.e. those who had either contracted COVID-19 or had had two doses of vaccine 6 months earlier) provide additional protection against omicron variant infection and subsequent disease.
\NSource: skai.gr
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