The first preliminary data provide an indication of the extent to which the Omicron variant of SARS-CoV-2 is able to nullify the immune protection provided by vaccination: this reduction would be obvious, but not complete. According to analyzes by working groups Sandra Ciesek of the University Hospital Frankfurt am Main, Germany and Alex Segal of the University of KwaZulu-Natal in Durban, South Africa, antibodies made up of two doses of vaccination hardly offer protection. Measurable against infection, but a third dose of vaccination as well as the combination of infection and vaccination significantly mask the virus. Another study by a group led by Daniel J. Sheward of the Karolinska Institutet in Stockholm suggests significant residual protection, especially through a combination of vaccination and infection.
This indicates that Omicron largely escapes existing immunity and is likely to lead to many breakthroughs in vaccines. However, the loss of protection provided by vaccination is not complete. The studies do not measure the actual protection that vaccines provide, but rather how powerfully the antibodies present prevent the virus from infecting cells. This laboratory value cannot be directly converted into effective vaccine protection.
So experts still expect vaccines, in particular, to significantly reduce severe disease cycles. Virologist Florian Kramer wrote on Twitter: “I assume protection against acute illness remains reasonably high in immunized individuals.” This can be attributed to several factors, such as non-neutralizing antibodies and T and B cell activity.
Same future, less protection
Ciesek and Sigal’s research groups worked directly with samples of a virus variant first isolated in South Africa, while Sheward’s group worked with a synthetically produced protein-expressing pseudovirus. escalate. To determine the effect of the antibodies produced by the vaccine, experts tested how effective the antibodies were at blocking the virus in blood samples. Sigal Group And so check Protection of 12 people vaccinated with the Biontech vaccine. Six of them also contracted the SARS-CoV-2 virus. In tests, the protective effect was reduced by an average of 41 times compared to the original virus, but not equally in all test subjects. Five of the six people who recovered showed significant antibody protection.
In another study, Sigal found that Omicron was still dependent on the cellular ACE2 receptor: the virus infected cells whose group had artificially endowed the ACE2 receptor, but not the unmodified precursor to these cells. Given the apparent mutations in the virus, experts feared that the pathogen had switched to a different molecule as an entry point, making the epidemic more difficult to fight. “This is better than I expected for Omicron,” Sigal wrote on Twitter, commenting on the results. “This means we can tackle the problem with the resources we have.”
In the origin of the variable Omicron
According to the researcher, similar results were obtained by the Ciesek research group (publication not yet available). The study found that antibodies stimulated by two doses of the Biontech vaccine, Moderna vaccine and cross-vaccination with AstraZeneca and Biontech did not provide measurable protection six months after the second vaccination. On the other hand, a third dose of vaccination increases the efficacy of the antibodies to 25 percent after three months, which also indicates that Omicron does not completely escape immune protection. According to Ciesek, protection has been reduced by 37 times compared to Delta. Furthermore, the team showed that the antibody drug Ronapreve, composed of the monoclonal antibodies Imdevimab and Casirivimab, which is used in high-risk groups, appears to have no effect against Omicron.
Swedish study results From the Sheward group a little more encouraging. It indicates a slight decrease in the protective effect compared to the analyzes by Ciesek and Sigal. The team tested blood samples from 17 donors who had antibodies to SARS-CoV-2 and from 17 people working in clinics who had already been vaccinated and infected. According to the results, the deterioration in immune protection is highly variable, ranging from no regression to factor 23 compared to the protective effect against the original virus.
However, the booster is useful
People who were not only vaccinated, but also infected had the best protective effect. However, the study does not provide any information about how often and when the people tested were vaccinated; Furthermore, this study is considered less relevant due to the placebo virus used.
It is assumed that a specific vaccine against the new variant will arrive. According to the data, the development of a vaccine adapted to Omicron makes sense, Ciesek writes on Twitter. Experts have long predicted that SARS-CoV-2 vaccinations will need to adapt to new variables over time. Shortly after its discovery, Biontech announced that it would test the new variant of the virus and eventually begin developing a vaccine.
The same company says it has already made arrangements with its US partner, Pfizer, to adapt the vaccine to so-called escape alternatives, such as Omicron, within six weeks. This includes ongoing studies with already developed “specific variant vaccines” that Biontech intends to use as sample data for approval of a modified vaccine.
In mRNA vaccines, only a few points in the sequence of the used gene blocks have been altered, while the rest are identical to the previous type: for this reason, vaccines adapted to the mutations are supposed to behave in the same way as the original ones. If proven, such a type of vaccine could be approved very quickly. Biontech has announced that a modified vaccine can be distributed within 100 days. But since these adapted vaccines won’t be available until February or March 2022 at the earliest, you shouldn’t expect them. Vaccination with even the third dose helps now.
(The original of this article was pubblicato su “Spectrum of Science” l’8 December 2021. Translation and editing by Le Scienze. Reproduction authorized, all rights reserved.)
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