Two vaccinations and a booster, a breakthrough disease after two vaccinations or two vaccinations after one illness – in all three cases, the study published in “NatureMedecine” demonstrated a high-quality antibody response of the immune system to the coronavirus.
The antibodies formed are not only available in sufficient quantities, but they are also capable of neutralizing new variants of concern (VOC) such as Omikron at present.
Study with 170 subjects
A team led by Ulrike Protzer, Head of the Institute of Virology at the Technical University of Munich, has accompanied over 170 volunteers from the staff at the Klinikum Rechts der Isar since the beginning of the pandemic. One group was infected with SARS-CoV-2 in the first pandemic wave in spring 2020, a second was not.
Later, both groups were offered vaccinations with BioNTech/Pfizer’s mRNA-based COVID-19 vaccine and they were followed up for almost two years.
Several parameters were determined in the blood of the test persons: the amount of antibodies (IgG), the strength of the bond between virus protein and antibody and the ability of antibodies to neutralize SARS-CoV-2 variants in cell culture. The latter two are particularly important for estimating the extent of protective immunity.
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More antibodies needed against omicron
The study showed that the immune system’s ability to neutralize the virus was only partially correlated with antibody titer (amount). Rather, the decisive factor is how effectively these antibodies bind to the virus and thus inactivate it. It was confirmed that Omikron “escapes” the immune system more easily than earlier variants. According to the author of the study, this requires “significantly more and better antibodies to neutralize the virus”.
It was shown that “people need three times contact with the spike protein so that, according to the current state of knowledge, there is a very good neutralizing activity against all VOCs, including omicron”.
The threefold contact can take place in different constellations. People who had been vaccinated three times without a previous SARS-CoV-2 infection had almost the same titers of neutralizing antibodies against the omicron as those who had recovered or had a breakthrough infection with the delta or omicron. In all cases, the neutralization activity reached similarly high levels in the analysis, and the binding strength of the antibodies increased in all constellations. (SDA)
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