Anti-SARS-CoV-2 antibodies produced in laboratories block the virus by interacting with its spike protein, which the virus attaches to receptors on cells. Omicron has 30 mutations in this protein, and this could be of enormous importance from the point of view of immunity.
The coronavirus pandemic. New research results regarding the omicron variant
A team by David Ho from Columbia University tested the effectiveness of vaccines from Pfizer, Moderna, Johnson & Johnson and AstraZeneca in samples from 54 fully vaccinated people. These researchers observed a ‘significant drop in effectiveness’ of all vaccines against the new variant. This also applied to study participants who had previously become infected. People vaccinated with the Pfizer and Moderna preparations, who received a booster dose, had a smaller decrease in effectiveness.
Researchers also tested 19 monoclonal antibodies (developed for therapeutic purposes). Among them were: imdevimab, casirivimab, tixagevimab, cilgavimab, bamlanivimab, etesevimab, amubarvimab, romlusevimab, and sotrovimab. It turned out that 17 of the tested antibodies lost their effectiveness partially or completely. The authors also described four mutations of the virus that led to the described change.
In turn, researchers from the French Pasteur Institute checked the effectiveness of nine therapeutic monoclonal antibodies. Antibodies bamlanivimab, etesevimab, casirivimab, imdevimab and regdanvimab were inactive, cilgavimab and andintrevimab were 20 times weaker compared to the delta variant, and sotrovimab was three times weaker.
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Research on the omicron. Scientists: Antibodies less effective against the new virus variant
The researchers also exposed the virus to plasma collected from vaccinated people who had not been infected. They did not detect the antiviral activity of the Pfizer and AstraZeneca vaccines in the samples taken five months after receiving the second dose. In the case of people vaccinated with three doses of Pfizer’s preparation, the effectiveness in neutralizing the omicron variant was six times lower. On the other hand, tests on samples taken from convalescents six or 12 months after symptom relief showed no or little effectiveness of the antibodies. However, those who fell ill and then took one dose of the Pfizer vaccine were more resistant than the double vaccinated, but with no medical history.
The authors of the next study are scientists from the Africa Health Research Institute in Durban. In a study involving 19 volunteers, they noticed a 22-fold decrease in the effectiveness of the Pfizer vaccine compared to its action against the original variant of the virus in people who did not have the disease. Vaccinated people who became infected had similar levels of immunity to those who had been vaccinated against the primary virus alone.
Another study was conducted by scientists from the Swiss company Humabs. They first checked how strongly the part of the spike protein that binds to cell receptors interacts with these receptors. It turned out that it attached 2.4 times more strongly than in the original Wuhan viruses.
How do vaccines work on omicrons? Scientists presented the results of the research
Scientists also tested therapeutic monoclonal antibodies. One of the eight antibodies has almost completely lost its effectiveness. Two (used together) worked 100 times weaker, and one – three times weaker. Of the 44 antibodies tested, six were functional.
In contrast, the Johnson & Johnson, Sputnik V and Sinopharm vaccines had little or no effectiveness. Preparations of Moderna, Pfizer-BioNTech and AstraZeneca were 33, 44 and 36 times less effective, respectively.
The authors of the latest study are specialists from the University of Beijing. Of the 247 human antibodies they tested, omicron was able to avoid 85 percent of the effects. of them. Scientists also described the effect of specific mutations in the receptor-binding part of the spike protein on human cells. In addition, they found that the new variant was significantly less responsive to therapy based on two antibodies – etesevimabi bamlanivimab (REGEN-COV), cilgavimab-tixagevimab antibodies and amubarvimab. Two antibodies, sotrovimab iDXP-604, worked, but weaker.
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(PAP) Author: Marek Matacz
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