Would it be useful to postpone the second dose of the Pfizer-Biontech vaccine to give the first injection to as many people as quickly as possible? The international scientific community does not answer this question with one voice. The result is that in several countries the postponement is being discussed to remedy two still unsolved problems: the scarcity of vaccines available and the logistical difficulties posed by mass administration.
The professor fuels the debate in Italy Joseph Remuzzi, director of the Negri Institute, who in an interview with Corriere della Sera is in favor of the postponement: “It is better to vaccinate a large number of people with a single dose than a small sample with two doses. It can be hypothesized not to make the recall before 120 days have passed".
THEItalian Medicines Agency (Aifa) he merely writes that the vaccine is administered in two injections "at least 21 days apart". That'almeno it doesn't help solve the problem. not even theEuropean Medicines Agency (Ema) indicates precisely when to carry out the second administration. In any case, in the documentation that led to the authorization of the vaccine, the hypothesis of postponing the second dose is not contemplated.
THEWorld Health Organization (WHO) however, it expressed itself more explicitly, opening up the possibility of extending the time interval between the two doses from 21 to 42 days (6 weeks). The option, however, can only be evaluated in two exceptional cases: "Problems of supply" and "serious epidemiological situation", specifies the WHO.
THEUS Medicines Authority (Food and Drug Administration, fda), instead took sides clearly against the hypothesis of the postponement: "They are reasonable options to consider and evaluate in clinical trials - said the agency officials - However, at this time, suggest changes to the dosage authorized by the FDA or to programs for these vaccines is premature and not firmly rooted in the available evidence. Without appropriate data, we run a significant risk of jeopardizing public health by undermining historic vaccination efforts to protect the population."
The American virologist is also against it Anthony Fauci, confirmed as a medical adviser also in the Biden administration: “We know from the clinical trial that the optimal time to give it is day one and then wait 28 days for the Moderna vaccine and 21 for the Pfizer one”.
In terms of individual countries, Great Britain it was the first to take the side of the postponement and is thinking of extending the interval between the first and second dose even to 12 weeks, double what is recommended by the WHO.
The government of United StatesIt is currently withholding 50% of the vaccine supply to ensure second doses are available, but President-elect Joe Biden - who officially takes office Jan. 20 - has announced plans to release every available dose immediately.
The discussion is also heated in Germany, where the government would like to speed up the spread of the vaccine and several health authorities have said they are in favor of an approach similar to the British one.
La Denmarkfinally decided to delay the second injection for up to six weeks.
As for the manufacturers, in the experimentation of the vaccine Pfizer and BioNTech have taken into consideration only the case of the two doses administered three weeks apart and recommend following this indication.
UPDATE JANUARY 13
The Scientific Committee for the surveillance of Covid-19 vaccines (Csv) of theAIFA "considers it necessary to adhere to the current indications for the administration of two doses for the vaccines approved so far”, reads the AIFA website in the Faq section, which has recently been updated. "We don't know how long immunity lasts after a first dose - notes the CSV - A population vaccinated with a single dose sees its risk of falling ill with Covid only halved".
