COVID-19 | The two doses of the vaccine increase the levels of antibodies in the respiratory tract

Antibodies in the respiratory tract decrease rapidly after infection with the SARS-CoV-2But vaccination causes a sharp rise in antibody levels, especially after two doses, according to a new study from Sweden’s Karolinska Institutet published in the journal JCI Insight.

The results of this research suggest that receiving a second dose of the vaccine also after recovering from COVID-19 may be important for

“What makes the study unique is that we have analyzed samples from both the blood and the respiratory tract, giving us new insights into the local immune response where the virus infects. As it is more difficult to take samples from the respiratory tract, we know much less about the levels of antibodies there than in the blood ”, says study co-author Anna Smed-Sörensen, a professor and research group leader at the Karolinska Institutet’s Department of Medicine in Solna.

In their study, the researchers examined how the levels and durability of antibodies to SARS-CoV-2 differed between individuals who had mild or severe COVID-19. 147 patients were recruited between March and May 2020 and

In 20 of the patients, they also studied antibody levels after vaccination (with the AstraZeneca, Pfizer-BioNTech, or Moderna vaccine) and compared the results with a control group that

Their results show that individuals with the most severe COVID-19 illness had higher antibody levels after recovery compared to individuals with mild illness.

Antibodies in the blood remained at measurable levels for at least eight months, while those in the respiratory tract (for example, the nose) and disappeared after three months.

“The positive news is that the antibodies quickly returned after vaccination in those who had previously had COVID-19, not only in the blood but also in the respiratory tract. We found that the levels of antibodies in the airways after two doses of the vaccine than during the course of the disease. People who had not had COVID-19 prior to vaccination had much lower or undetectable levels ”, dice Smed-Sörensen.

In COVID-19 patients, the second dose of the vaccine did not have as strong an effect on antibody levels in the blood. This is in line with previous studies on the antibody response in the blood, in which people who had previously received COVID-19m, but only a small increase – if any – after the second.

The level of antibodies required for protection against infection is still unknown, as is whether the rapid decline in antibody levels in the respiratory tract allows reinfection. The researchers will now continue to analyze additional longitudinal time point samples and examine the inflammatory environment in the airways during infection, convalescence, and after vaccination.

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