Will a third booster dose of the covid vaccines be needed? The answer is simple: we don’t know yet. Today the epidemiologist of the Istituto Superiore di Sanità Gianni Rezza explained how a decision will be made within a month but that probably the most fragile and immunosuppressed people will have to undergo a new anti-covid vaccine booster. The field of study will be Israel: as at the beginning of the vaccination campaign, the Middle Eastern country will constitute a real laboratory to understand the duration of the immune protection against Sars-Cov-2 infection. Here, in fact, the government will start from Sunday to recall the over 60s who received the second dose 5 months ago: the decision after research by the Israeli Ministry of Health showed that the Pfizer vaccine was only 16 percent effective against the Delta variant in people vaccinated for over six months. The same pharmaceutical company he had declared that the third dose of his vaccine could induce production of neutralizing antibodies against the delta variant five times higher in younger people and more than 11 times higher in older people than two doses.
But is it a necessary precaution? The scientific community is also divided because – as happened very often during the pandemic – there are no consolidated data to think about. On the table of the technicians of the Ministry of Health there is already the hypothesis of a plan that could foresee a third dose for some specific categories of people, immunosuppressed and frail in the first place. If the European regulatory authority Ema takes time to analyze the data, the World Health Organization focuses on the fact that a large part of the world population has not yet had access to vaccination and constitutes a continuous endemic reserve for the coronavirus that can replicate itself. freely and produce even more dangerous variants of the delta.
The question remains, will the third dose be needed? Perhaps a further recall will not be necessary as AstraZeneca CEO Pascal Soriot explains. “Whether a third dose will be needed is still unclear, only time will tell,” she told cnbc explaining how the double “dimension” of immunity is often forgotten: if the antibodies decrease over time, there is a cellular immunity mediated by T cell which tend to protect people from serious illness for a longer time. “With the technology we use, we have a very high production of T cells. We hope to have a durable vaccine that will protect for a long period of time”, explained the manager of the Anglo-Swedish company which could thus have a kind of revenge on ‘ rivals’ Pfizer and Moderna who have instead made mRNA vaccines. A recent study showed that Pfizer / BioNTech vaccine efficacy drops by an average of 6% every two months to 84% four to six months after the second dose.
How long does vaccine protection last
The issue of the duration of immune protection linked to T lymphocytes is often underestimated. They are white blood cells that play different roles in the immune system, from attacking pathogens to supporting other white blood cells in the production of antibodies. In practice, antibodies prevent viruses from invading cells but have a shorter duration than T lymphocytes, which instead attack infected cells, preventing the virus from replicating.