The protective effect of antibodies against omicron decreases rapidly –

Antibodies against omicron quickly lose their effectiveness

According to a recent study, antibodies directed against the omicron variants BA.1 and BA.2 of the SARS-CoV-2 coronavirus, dominant from December 2021 to April 2022, can lose their protective effect after only a few months. This applies to antibodies after infections as well as after vaccinations.

Researchers at Goethe University Frankfurt am Main investigated how long antibodies in the blood were able to neutralize the Omicron BA.1 and BA.2 virus variants after vaccination or after illness. The results were recently presented in the renowned journal The Lancet eBioMedicine.

Omicron quickly became the dominant variant

The omicron variant of the SARS-CoV-2 coronavirus was first documented in November 2021 in South Africa. The variant quickly spread around the world. The reason is that omicron is characterized by a high level of infectivity and can quickly produce other subvariants.

In Germany, too, Omikron established itself in no time. In January 2022, the omicron BA.1 subvariant first became widespread in Germany. In the months that followed, the BA.2 variant was added, which dominated until June 2022 and was later replaced by the BA.4 and BA.5 sub-variants.

As quickly as the subvariants change, immune protection against omicron appears to be just as short-lived, as an ongoing German study suggests.

A great challenge for our immune system

As the working group explains, the rapid change in subvariants also poses a major challenge for the human immune system. Antibodies that form to defend against the virus during an infection bind to the surface structures of the virus in order to neutralize it.

However, these structures, of which the so-called spike protein is the most important, constantly change from variant to variant. Compared to the original Wuhan virus, the spike protein of the omicron variants has already changed in more than 50 places.

A consequence of this is that antibodies that have formed against a specific variant or subvariant are less able to recognize and bind to another variant or subvariant.

Reason for recurrent infections

Therefore, in recent months, many people have again fallen ill with COVID-19 within a few months, although they survived the infection or vaccination. Researchers from the Institute for Medical Virology at Frankfurt University Hospital and Goethe University have now looked in more detail at how long antibodies last against the Omicron BA.1 and BA.2 virus variants.

To do this, the team took blood samples from doubly and triply vaccinated people and combined the antibodies from the samples with corona viruses from cultured cells. In this way, scientists were able to observe how effectively different antibodies could neutralize viruses.

Antibodies quickly lost their protective effect

It turned out that the antibodies acquired more than six months ago no longer had a neutralizing effect on the omicron BA.1 and BA.2 variants. Antibodies acquired by booster vaccination had only a weak protective effect against omicron after only three months.

Antibodies are less able to recognize new variants

“This is because the antibody titer in the serum – the amount of antibody, so to speak – decreases over time after a vaccination or infection,” says Dr. Marek Widera, who led the study. with Professor Sandra Ciesek.

“Because antibodies recognize new viral variants much worse, a lower antibody level is no longer sufficient to neutralize viral variants and prevent infection of cells in cell culture,” explains Widera.

“However, the data from this study only allow conclusions to be drawn about the risk of infection and no assertions about protection against severe disease progression,” concludes the research director. According to him, the cellular immune response is decisive for the immune defense and not the antibody titer. However, this was not examined in the study.

“Our study shows that we must not relax the adaptation of our protective measures to genetic modifications of the SARS-CoV-2 virus, currently to the omicron variants BA.4 and BA.5”, emphasizes Professor Ciesek in conclusion. (vb)

Author and source information

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This text corresponds to the specifications of the specialized medical literature, medical guidelines and current studies and has been verified by health professionals.

Author:

Graduate editor (FH) Volker Blasek

Sources:

Goethe University Frankfurt/Main: The effect of antibodies against omicron variants BA.1 and BA.2 decreases rapidly (Published: 07/22/2022), aktuelles.uni-frankfurt.deAlexander Wilhelm, Marek Widera, Sandra Ciesek, et al. : Limited neutralization of SARS-CoV-2 Omicron BA.1 and BA.2 subvariants by convalescent and vaccine serum and monoclonal antibodies; in: eBioMedicine (2022), thelancet.com

Important note:
This article contains general advice only and should not be used for self-diagnosis or treatment. It cannot substitute a visit to the doctor.

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