Two Vaccine Doses Elevate Antibody Levels In Airway After COVID-19: Study

SOLNA: Antibodies in the airways quickly decrease after COVID-19 , but vaccinations result in an exponential rise in antibody levels, especially after two doses, says a new study from Karolinska Institutet which was published in the journal JCI Insight. The results advocate that having a second vaccine dose right after recovering from COVID-19 may prove significant for protecting against re-infection and limiting transmission.

“What makes the study distinctive is that we have looked at both samples from airway tracts and blood, which has given us a new perspective of the local immune response. Since it is more difficult to sample the airways, we know much less about antibody levels there than in the blood,” says co-author Anna Smed-Sörensen, research group leader at the Department of Medicine, Solna, Karolinska Institutet.

In their study, the researchers examined how the antibody durability and number fluctuated between individuals who had mild to severe COVID-19. 147 patients were monitored for up to eight months after infection. In 20 patients, they also observed antibody levels after vaccination and compared those results with a control group.

According to the results, severe COVID-19 survivors had higher antibody levels upon recovery compared to those with milder cases. The antibodies in the blood remained for at least eight months, while those in the airways disappeared after three months.

“The positive news is that the antibodies quickly returned after vaccination in those who previously had COVID-19, not only in the blood but also in the airways. We found that the antibody levels in the airways after two doses of vaccine were often even higher than they were during the course of the disease. People who had not had COVID-19 before vaccination had much lower or undetectable levels,” says Dr Smed-Sörensen.

“Our results validate that only blood alone does not reflect the antibody levels in the respiratory tract. A second dose may therefore be important for achieving optimal immune responses and reducing the spread of infection between individuals,” says co-author Karin Loré, professor at the Department of Medicine, Solna, Karolinska Institutet.

Publication: “Airway antibodies emerge according to COVID-19 severity and wane rapidly but reappear after SARS-CoV-2 vaccination”.