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| Charlotte Thålin, assistant chief physician and associate professor at Department of Clinical Sciences, Danderyds Hospital, Karolinska Institutet, led the study. Credit: Ludvig Costyal |
The COMMUNITY study started in the spring of 2020 with a provincial collection of 2,149 employees at Danderyds Hospital. The study participants and their immune response to the coronavirus sars-cov-2 have since followed up every four months. At the beginning of 2022, a study was conducted in which 338 employees who received three doses of vaccine were regularly screened for SARS-Cov-2 infection. Of those who were not infected at the start of the study, sixth participants (57 people) were infected with omics during the course of the study. This allowed the research team to investigate what protects against infection and what the immune response after omicron infection looks like.
Halved risk of being infected
Among other things, the levels of IgA antibodies (immunoglobulin A) were measured in the airways, which play an important role in the body's defense against respiratory tract infections. After three doses of vaccine, when screening began, most had high levels of antibodies in the blood, but only 62 percent had measurable antibodies in the airways. Those individuals who had high levels of IgA antibodies in the airways had a halved risk of being infected by omicrons.
It is not surprising that antibodies in the airways neutralize the virus locally, but we have now been able to show for the first time that sars-cov-2 antibodies in the airways actually protect against omicron infection, say Charlotte Thålin, assistant chief physician and associate professor at Department of Clinical Sciences, Danderyds Hospital, Karolinska Institutet, who led the study.
Among those infected with omicron, researchers could see that individuals with measurable antibody levels in the airways had lower levels of SARS-Cov-2 virus. Following omicron infection, the majority received a 40-fold increase in antibodies in the airways, although the infection was mild.
The researchers were also able to show that the participants who had covid-19 before being vaccinated had significantly higher levels of sars-cov-2-specific antibodies in the airways after vaccination than participants who had not covid-19 before vaccination. This may explain why so-called hybrid immunity, the combination infection and vaccine, provides stronger protection against infection than just vaccine.
Vaccine in nasal spray form is being investigated
Now we are in a position with omicrons that infect despite several doses of today's vaccines given in the muscle. It is tempting to believe that a vaccine that is instead given through the nose / airways, where the virus enters the body, could provoke a similar immune response locally as a natural infection and thus stop the virus at an earlier stage. Several nasal spray vaccines are now being investigated in clinical trials with the hope of reducing the spread of infection and thus reducing the risk of developing new virus variants, says Charlotte Thålin.
The COMMUNITY study continues with regular sampling and follows the immune response following repeated SARS-Cov-2 infections and vaccinations. The study is run and conducted in close collaboration between Danderyd Hospital, Karolinska Institutet, Uppsala University, the Public Health Authority, KTH and SciLifeLab.
The research has been funded by the Jonas and Christina af Jochnick Foundation, Region Stockholm, Knut and Alice Wallenberg Foundation, Leif Lundblad with family, Swedish Research Council, Hjärt-Lungfonden, Bill and Melinda Gates Foundation, Karolinska Institutet and SciLifeLab.
Source/Credit: Karolinska Institutet
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