The fourth dose of Covid-19 vaccine for over 50s has been approved in the United States

The fourth dose of Covid-19 vaccine for over 50s has been approved in the United States

In the United States, the Food and Drug Administration (FDA) has just authorized the fourth dose - the second booster - of the vaccine against Covid-19 for those aged 50 and over. The booster was already recommended for people with severe impairment of the immune system, to which today the over 50s are added. The approval concerns the messenger RNA vaccines, namely those of Pfizer and Moderna, on which there is more data, and plan to administer the booster at least 4 months after the previous injection.

The extension of the fourth dose, which is currently still the subject of debate in Europe, is based on the absence of concerns about safety and is motivated by the decline over time in protection due to the vaccine, which may represent a risk especially for the elderly or immunocompromised.

The evidence gathered on the fourth dose In the United States, the Pfizer and Moderna companies have recently submitted the request to the FDA. The authority's authorization was based on data collected in Israel, where the vaccination campaign is further ahead. The results, still under publication, demonstrate the absence of new reports on the safety of mRna vaccines in the weeks following the booster. In particular, in the case of Pfizer's vaccine, there have been no significant effects or events, other than those already known, on the basis of 700 thousand fourth doses administered. -print on medRxiv, indicates that the new booster brings the anti-Sars-Cov-2 antibody level back to that obtained with the third dose. However, the additional protection against symptomatic but mild infections would be somewhat reduced. The research in question included 154 healthcare workers vaccinated with Pfizer and 120 with Moderna.

Another study, also conducted in Israel and traceable to medRxiv, reports that in people over 60 the fourth dose could increase protection, especially against severe forms. The survey included more than 1.1 million individuals over 60, some of whom also received the additional recall. The result shows that in a specific moment of time the incidence of new infections in those who have had the fourth dose for at least 12 days is lower by a factor of 2, ie it is halved.

Against Covid-19 serious in those at risk In short, on the basis of the evidence gathered, the vaccine would be useful above a certain age - the threshold has often been the subject of debate - and in the case of previous pathologies. Immediately following FDA clearance, the US Centers for Disease Control and Prevention (CDC) stress that the fourth dose is safe and that it is "especially important for people over 65 and over 50 and underlying medical conditions that increase the risk of severe forms of Covid-19 ", which are the ones that benefit the most.

What is said in Italy? Currently in Europe and in Italy the fourth dose is recommended only to individuals with a "marked impairment of the immune response", linked to specific pathologies, treatments or organ transplants, at least 4 months after the previous one. Quite recently (March 17, 2022) the European Medicines Agency (EMA) stated that there is not enough evidence in Europe to extend the fourth dose of the coronavirus vaccine to everyone.

In the meantime, the manufacturers Pfizer and Moderna have submitted the request for authorization of the second booster to the American FDA, which in the light of the data provided has given the new green light on March 29 to people over 50 years old . Also in mid-March, the Minister of Health Roberto Speranza announced that the possibility of extending vaccination to more advanced age groups, as well as to people with immunocompromised, will be studied on the basis of discussions with the scientific community. On the basis of all this information it is therefore possible that there will be some updates for us in the short term.

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