After just 7 days, 95.6% protection against infections is achieved and is also valid in the presence of the Delta variant. In some cases the recall not only bridges the decline in effectiveness that is recorded over time, but reaches higher values in absolute
Good news regarding the effectiveness of the third dose. The New England Journal of Medicine posted Thursday the first randomized study of a Pfizer booster administered on 10,000 people, controlled with placebo (the “gold standard” in drug research): so far there had only been analyzes without “control groups”, therefore with more potential factors of error .
High efficacy after 7 days
The results of this research, presented to the Advisory Committee of the Food and Drug Administration (the US government agency that deals with the regulation of food and pharmaceutical products), show a third dose efficacy of 95.6%, very high, with 5 cases of coronavirus infection in the group vaccinated with the third Pfizer dose, compared with 109 infections in the placebo group (2 Pfizer doses, plus the third with placebo). The optimistic figures are reinforced by the fact that neutralizing antibodies have been high against all variants, without particular drops towards the “worst”, Beta and Delta. In addition, to reach the maximum effectiveness of the third dose we have seen that it only took 7 days. More than a fifth of the study participants were over 65, the category most at risk of severe Covid. The safety profile of the vaccine also remained ‘generally consistent’ with previous data.
Protection is achieved that exceeds the initial one
The numbers of effectiveness concern contagion: the ability of vaccines to combat deaths and hospitalizations is greater than 90 percent (and close to 100%) in every analysis, even “only” with the two doses of vaccine, but the protection against infections weakens and drops after six months, especially in the most exposed categories, for which the third dose is useful. Thanks to this study it is possible to think that the protection after the third dose comes to be almost total, an excellent result if we consider that the Italian data of the Istituto Superiore di Sanità (ISS) have measured, seven months after the second dose in the population general, 89% effectiveness, which drops further in the presence of Delta and falls again in people with comorbidities: from 75% (after 28 days from the second dose) 52% after seven months. The efficacy against infection in people over 80 and in RSA residents also decreases after seven months (although not below 80%).
The third dose, to whom it will go
In Italy the third dose is given, in order of priority, to the immunocompromised, over 80, residents of the RSA, health personnel, over 60 and frail. However, an extension to the under 60 age bracket is being considered, but from January. The booster is in any case done with Rna vaccine.
Marco Cavaleri, head of the vaccine strategy division ofEuropean Medicines Agency (EMA), stated that the agency will evaluate the data of this study to consider the hypothesis of expanding the number of recalls, currently foreseen for the most fragile population groups.
In the USA the FDA gave the green light to any high-risk Covid citizen to receive an additional dose of any approved vaccine.
Do you call back every year?
What remains to be seen is how long, with the third dose, will you stay protected. It is still too early to know: as has happened in recent months, we look to Israel, where studies are more advanced in time. In any case you don’t necessarily need an injection every six months. There are some vaccines for which, after two or three doses, the protection lasts for years. Although Covid-19 has been with us for almost two years, the unknowns are still many: some doubts have been resolved over time, others are added gradually.
October 22, 2021 (change October 22, 2021 | 12:41)
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