Covid vaccine: third dose yes, third dose no. The debate on the need or not of a ‘booster’ for vaccinated against Covid-19 is currently premature and ill-placed according to internist Nino Mazzone, director of the Department of Medical Area, Chronicity and Continuity of care of the Asst Ovest Milanese, Civil hospital of Legnano. Among the Italian doctors infected during the second pandemic wave (in November 2020 he found himself hospitalized overnight in the department he directs), Mazzone is “fresh from the first dose to which I underwent according to ministerial indications”. But at Adnkronos Salute he anticipates a heartfelt appeal to the institutions: “Can we know the reinfection rates of vaccinated people to compare them with those of former Covid patients? Only after – he maintains – we could discuss the third dose”. “Before talking about it – explains the expert, vice president of FISM (Federation of Italian medical-scientific societies) – it is useful to know the data at one year of how many vaccinated people who had not had the Sars-CoV-2 infection become infected. We need clarity in comparing natural immunity “, that obtained by overcoming the disease,” and immunity acquired “through vaccination. “This data, which has not yet been produced, is instead fundamental – warns the doctor – to be able to decide on a strategy that must be planned worldwide”. Because “if the rates” of infection of cured and immunized “were similar, millions of vaccine doses could be saved”. Something like “300 million”, Mazzone estimates, to be donated “for the most vulnerable population of the world” or in any case useful for “enormously accelerating the vaccination of the categories that need it most”. “Also in light of the Delta variant” of new coronavirus, which has now become dominant in our country, for the specialist “the answer to a few simple questions (does it infect the vaccinated, and how much? Does it infect the cured, and how much?) will be fundamental in order to set quality policies based on a scientific methodology” . Mazzone is keen to first “clear away any misunderstanding”, confirming that “today two things appear fundamental” and that is “vaccinating all those who need it” and “using the Green pass to frequent closed places, including bars and restaurants “. That said, on the third dose the internist who has dressed both the smock and the pajamas invites “caution”. The same one that in his opinion should have already led to “waiting to vaccinate patients who have had Covid. The serological examination could have been carried out on the exposed – he reasons – and millions of doses and possible side effects would have been saved. “The doctor rests his reflection on solid foundations: a publication signed at the end of May in ‘Jama Internal Medicine’, where it appeared accompanied by a comment by Mitchell H. Katz of the New York Medical School, on the board of editors of the journal of the ‘American Medical Association. “The probability of reinfection for someone cured of Covid-19 is 0.07% at one year”, concluded in the paper Mazzone and colleagues, including the president of the Italian Clinical Microbiologists Association (AMCLI), Pierangelo Clerici. More precisely, “the incidence of Sars-CoV-2 infection per 100 thousand residents was 1 for people who had already contracted it and 15.1 for those who had never had it: a dramatic difference”. Results, those of the Legnanese team, in line with the data of several other studies. “There are various works published in the most important scientific journals, from ‘Nature’ to ‘The Lancet’ to ‘Nejm’ – recalls Mazzone – which demonstrate how long-term immunity of the healed is a reality, with antibodies traceable even after 12 months”. For example, “the Siren Lancet study addressed the relationships between HIV positive in people with previous Covid infection and the risk of severe acute respiratory syndrome due to reinfection over the next 7-12 months. Well, previous infection reduced the risk. of symptomatic reinfection of 93% “. Still, “a large cohort study published in Jama Internal Medicine examined 3.2 million US patients and showed that the risk of infection was significantly lower (0.3%) in HIV-positive patients with anti-Sars-CoV- antibodies. 2 compared to those seronegative (3%) “. Finally, “perhaps more importantly, a recent study indicates the presence of long-lived memory immune cells in those who have recovered from Covid-19. This implies a lasting ability, perhaps years long, to respond to a new infection with new antibodies “. “It is clear that immunity induced by a previous Sars-CoV-2 infection is more unstable than vaccine induced immunity, but we – the internist clarifies – are interested in the real clinical differences between those with immunity. natural and some acquired: rate of reinfection, hospitalization, severity of symptoms, access to intensive care. These – Mazzone insists – are the comparative data between natural and acquired immunity that are needed to be able to choose the right vaccination strategies “. The problem noted by the expert is that at the moment, “in contrast to these objective evidence-based medicine data, which demonstrate adequate and lasting protection in those who have fallen ill with Covid-19″ and have overcome it, ” the duration of immunity induced by the vaccine is not completely known. So far over 10 thousand infections contracted at least 2 weeks after the completion of vaccination have been reported by the American CDCs, with a mortality of about 2%. An important incidence rate “which – associated to the recent warning issued by the White House immunologist Antony Fauci, that “about 20% of vaccinated people can be reinfected” – makes it “mandatory” according to Mazzone “to compare the true data of natural immunity and acquired immunity”. “to support with scientific evidence” those that already appear to the specialist “simple and logical concepts”. On the one hand, “the goal of vaccination is to generate memory cells capable of recognizing the Sars-CoV-2 virus and rapidly producing neutralizing antibodies that prevent or mitigate both infection and transmission.” On the other hand, “those who survived Covid must almost by definition have set up an effective immune response, as the studies cited above show”. This is why, “in our opinion – reiterates Mazzone – people for whom a Sars-CoV-2 infection has been confirmed may not need vaccination and do not need short-term vaccination”. And “considering the number of people who have become infected, hundreds of millions of doses could be released” to be put back ‘on the streets’ to try to hit an inescapable goal: to vaccinate anyone who needs to be vaccinated, anywhere in the world.