Two mRNA vaccines against COVID-19 have been shown to be safe and effective in clinical trials, as well as in the millions of people who have been vaccinated so far. But it is not yet known how previous SARS-CoV-2 infection affects vaccine response, nor how long does that answer last. Now a new study published in the journal ‘ACS Nano‘supports mounting evidence that people who have suffered from COVID-19 only need a dose of the vaccine, and that boosters may be needed for everyone in the future.
In clinical trials, COVID-19 vaccines from Pfizer-BioNTech and Moderna they were about 95% effective in protecting against symptomatic infections. Both mRNA vaccines cause the immune system to produce antibodies against the receptor-binding domain of the SARS-CoV-2 (RBD) protein, and two doses are necessary to provide immunity to people who have not previously been infected with coronavirus. .
However, very few people who had already recovered from the disease participated in clinical trialsTherefore, the immune response of these individuals is less well known. Furthermore, the time course of antibody development in both groups has not been well characterized, nor how long the virus neutralizing antibodies persist.
For this reason, Otto Yang and his colleagues at the University of California, Los Angeles (UCLA) wanted compare the levels, quality and persistence of antibodies after one and two doses of mRNA vaccine in people with or without previous infection by SARS-CoV-2. They used an enzyme-linked immunosorbent assay (ELISA) to measure RBD antibodies in people who received the Pfizer-BioNTech or Moderna vaccine, and in people not vaccinated shortly after mild or severe COVID-19 cases.
In the 28 participants without previous infection, one dose of either vaccine elicited antibody levels similar to those seen after mild COVID-19 infections, while two doses were required to obtain antibodies to RBD that approached those seen after severe cases. On the contrary, in 36 participants who had COVID-19 before Following vaccination, the first dose produced a vigorous antibody response similar to severe natural infection, but the second dose did not provide any further increase in antibody levels.
The quality of the antibodies, indicated by their ability to neutralize the spike protein of SARS-CoV-2 and its potency, continued similar patterns.
After the second dose of the vaccine, antibody levels decreased in both groups in a manner comparable to natural infection, with a mean loss of 90% in 85 days. Although more research is needed on T-cell responses to vaccines, this result suggests that booster vaccines are probably needed for allsay the researchers.