Studies have found that the neutralizing effect of antibodies against the Omicron mutants BA.1 and BA.2 declines rapidly.

An omicron variant of the SARS-CoV-2 virus was first detected in South Africa in November 2021. The high levels of infectivity of the virus and its ability to rapidly generate additional mutants have also been observed in Germany. Omicron mutants since January 2022 BA.1 is predominant here, followed by variant BA.2 in the coming months. In the meantime, the virus mutated further, and since June, variants BA.4 and BA.5 have replaced its predecessors.

This poses a major challenge to the human immune system. Antibodies are formed during SARS-CoV-2 infection and attach to the surface structure of the virus, preventing the virus from invading human cells. Viral peplomer plays an important role here. In the Omicron variant, this has changed at more than 50 sites compared to the SARS-CoV-2 virus first identified in Wuhan. Results: Antibodies formed after infection or vaccination do not recognize inefficient mutants. This is why, despite overcoming the infection, people can be infected with the new SARS-CoV-2 mutant again, or there are breakthrough infections. However, antibodies are not the only factor in the immune response to infection.

Researchers in Frankfurt, led by Professors Marek Kidera and Sandra Ciesek of the Institute of Medical Virology at the Goethe University Hospital in Frankfurt, investigated how long the antibodies present in the blood could still be neutralized after vaccination or recovery from infection. Viral variants Omicron BA.1 and BA.2. For this purpose, they collect blood samples from people who have been vaccinated a few times (booster shots) and transfer liquid blood components (serum) containing antibodies to cultured cells with SARS-CoV-2 virus. Number of infected cells placed and observed. In addition, in each case, we confirmed the amount of antibody in the sample that recognizes the spike protein.

RESULTS: Six months after the second vaccination, the sera tested showed virtually no neutralizing effect on the Omicron mutants BA.1 and BA.2. The effect of booster vaccination declined rapidly: the serum immediately after booster vaccination still provided very good protection, but after 3 months the protective effect was very weak and the tested serum was no longer 2 A variant that was unable to neutralize one virus. “this is, Antibody titer In serum (the amount of antibody, so to speak) after vaccination or infection has diminished over time, “antibodies have a significantly lower ability to recognize new viral variants, resulting in lower levels of antibodies. It is no longer sufficient to neutralize and prevent infection of cells during cell culture. However, the data in this study cannot draw conclusions regarding protection against the severity of disease progression. ” The decisive factor is not only the antibody titer, but also the cellular immune response. Widera adds that it has not been considered in this study.

These results show that the use of monoclonal antibodies given to patients with a weakened immune system as a precautionary measure is particularly problematic, says Professor Sandra Sisek. Ciesek is the director of the Institute for Medical Viral Sciences at the University Hospital of Frankfurt and the lead author of this study. She explains: “As an example, we studied three such monoclonal antibodies in laboratory experiments, Effectiveness It is very dependent on the variant of the virus. To be able to protect vulnerable patients with such formulations, it is also imperative that patients be tested to the extent that such antibodies can neutralize the viral variants that are currently prevalent. Indeed, viral variants BA.1 and virologists added that the BA.2 examined in this study was no longer predominant in Germany during that time. Therefore, the CoV-2 virus is currently infecting the Omicron variants BA.4 and BA.5. “