Washington: People who have recovered from Covid-19 need only one dose of vaccine. A second jab is important for those who have not had Covid-19 to achieve strong immunity, a study suggests.
The study, led by researchers at the University of Pennsylvania in the US, found that Covid survivors had a robust antibody response after the first dose of mRNA vaccine, but after the second dose little immune benefit was seen.
On the other hand, those who did not have Covid-19 – called Covid naive – only had a complete immune response after receiving their second dose of vaccine, highlighting the importance of completing the two recommended doses for achieving a strengthened strong level of immunity. .
Two doses are optimal to elicit strong antibody and B cell responses in patients immunologically naïve to SARS-CoV-2, and antibodies caused by the vaccine may protect against the more contagious and deadly South African variant, the researchers said.
The findings, published in the journal Science Immunology, provide more insight into the underlying immunobiology of mRNA vaccines, which may help shape future vaccine strategies.
“These results are encouraging for both short- and long-term vaccine efficacy, and contribute to our understanding of the immune response to mRNA vaccine by analyzing memory B cells,” said E John Wherry, director of the Penn Institute of Immunology. , said.
The human immune response to vaccines and infections has two important consequences: the production of antibodies that provide rapid immunity and the creation of memory B cells that help with long-term immunity.
For the study, the team included 44 healthy individuals who received the BioNTech / Pfizer or Moderna mRNA Covid-19 vaccine. Of this group, 11 had a previous Covid-19 infection. Blood samples were collected four times for deep immunoassays before and after vaccination of the vaccine.
They confirmed that the mRNA vaccines cause antibodies that can neutralize the D614C and B1351 variants. These responses peaked one week after the second dose of vaccine in naïve patients, but peaked two weeks after the first dose in patients who recovered, with the same patterns in B-cell responses for both groups.
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