Covid-19: for those who have overcome the infection, the vaccine would be more effective if more time passes from the infection. And only one dose may be needed even after ten months. This is suggested by the result of a study by the Irccs Sacro Cuore Don Calabria in Negrar di Valpolicella (Verona), under review by the journal Clinical Microbiology and Infection, conducted on about 2,000 nurses and doctors. The antibody response to the mRNA vaccine in those infected with Sars-CoV-2 is higher if more time passes from the infection, especially in those who are young, in women and in those who have had symptoms of the infection. “A single dose seems sufficient in those who have contracted the virus, regardless of how long it has been since the infection”, comments the coordinator of the investigation Zeno Bisoffi.
But let’s get to the current state of affairs. Today, the time recommendation of the Ministry of Health is to carry out a single dose of vaccine in those who have had Covid-19 no later than 6 months after infection, after which a second dose is expected. However, this recommendation should be reconsidered in the light of the results of this new one. We can wait longer without fear that the vaccination will lose its effectiveness, indeed the opposite seems to happen. Lo A study by the Irccs Negrar, under review by the journal Clinical Microbiology and Infection, in fact, has shown that administering the mRNA vaccine ten months after infection leads to an even better antibody response than that obtained with inoculation closer to infection. The survey, conducted on about 2000 health workers, also verified that the antibody response is particularly strong in the youngest, in women and in those who have had a symptomatic Covid-19. In order not to waste precious doses of vaccine, the researchers therefore urge you to consider vaccinating anyone who has had Covid-19 with a single dose, regardless of the time elapsed since the infection.
The study was conducted between January and March 2021, when the health workers of the IRCCS Sacro Cuore Don Calabria in Negrar were subjected to anti-Covid vaccination with mRNA vaccine; the participants were tested for antibodies against Sars-Cov-2 at the time of the first and second dose and then a third time 2/3 weeks after the last inoculation. “We measured various classes of antibodies and in particular the quantitative IgG antibodies which include neutralizing ones, which with a certain approximation measure the response to the vaccine – explains the research coordinator Zeno Bisoffi, from the Department of Infectious Diseases and Microbiology at IRCCS – Of the 1935 participants, 232 had a documented history of infection, and in these healthcare workers the mean antibody titer after a single vaccine administration was significantly higher than in those who had never contracted the virus and received two doses of the vaccine. This confirms the observations of other researchers on lower numbers and corroborates the decision to proceed with a single administration in those who have already had Covid-19 “.
To date, however, this choice has been limited to 6 months after infection: in cases where more time has elapsed, a second dose of vaccine is provided, as happens for those who have never encountered the virus. The data collected by the Italian researchers show that it is not necessary, on the contrary: “With surprise we observed that the antibody response was stronger the longer the time had passed since the infection, up to over ten months; the answer is also more consistent in those who are younger, in women and in those who have had Covid-19 with symptoms – he adds Bisoffi – all this suggests that a single dose of mRNA vaccine is still sufficient in those who have had Covid-19, regardless of the time elapsed since the infection: considering that we cannot afford to waste precious doses of the vaccine, the single-dose vaccination criterion only within 6 months of the infection it could be revised to ensure that those who have had Covid-19 receive a single dose, always. The goal now is to verify these data in a population that has been vaccinated even longer after infection, to further corroborate the indication ”, concludes Bisoffi.