Scientists know that antibodies mucous membranes known as immunoglobulin A (IgA) can provide immunity against the virus respiratory. However, the potential role they have in protecting against infection by COVID-19 was still unknown. Now a study published in The New England Journal of Medicineled by researchers from Karolinska Institute and of Danderyd Hospitalin Swedenfound that high levels of antibodies in the mucous membranes of the respiratory tract reduce the risk of infection by Omicron variant.
“It is not surprising that the antibodies present in the respiratory tract neutralize the virus locally, but these findings show, for the first time, that the antibodies that are in the mucosa of the SARS-CoV-2 in the respiratory tract actually protect against Omicron infection,” explained the study’s lead author, Charlotte Thalinwho is also an associate professor at the Department of Clinical Sciences at Danderyd Hospital and member of Institute Karolinska.
The work, titled Community –which served as the basis for the development of the research-, enrolled 2149 workers health in the second trimester 2020 at the Danderyd Hospital in Sweden. Since then, study participants and their immune responses against the SARS-CoV-2 coronavirus have been followed every four months. In turn, a complementary study carried out between January and February 2022 evaluated others 338 employees of the same category vaccinated with three doses to detect infection by SARS-CoV-2.
The antibody levels in the blood and in the respiratory tract were determined at the beginning of the selective period, and one in six (57 participants) was subsequently infected with Ómicron during the selection stage of four weeks. This process allowed the research group to study the immunity against progressive contagion, as well as the immune booster later.
levels of IgA antibodies were measured in the respiratory tract because they play an important role in the protection against the respiratory infections. All participants had high levels of systemic antibodies after three doses of the vaccine, but only him 62% he had detectable antibodies in the mucosal airways.
At the same time, higher concentration of these indicators was associated with lower viral replication among those infected with Omicron. After infection, an increase in 40 times in respiratory tract antibodies in most participants, even if the infection had been mild.
The researchers also showed that participants with SARS-CoV-2 infection before of the vaccination had significantly higher levels Taller of antibodies after of the vaccination in comparison with the triply inoculated participants without previous infection. This may explain why the call hybrid immunitywhich is the combination of infection and vaccine, provides a protection stronger against infection than just vaccines.
“Now we are in a situation where Ómicron infects people despite having received several doses of the vaccines. intramuscular today,” Thålin said. And he added: “It is tempting to think that a vaccine administered through the nose or mouth – where SARS-CoV-2 enters the body – could cause a immune response that prevents infection at an earlier stage. Several vaccines are currently being marketed in the form of nasal spray. In addition, this continues to be investigated in clinical trials in the hope of being able to reduce the spread of the infection and thus reduce the risk of developing new variants of the virus, “concluded the specialist.