It goes from 21 to 42 days. Have followed conflicting statements between representatives of our health and pfizer institutions. In fact both sides do not disagree with each other, let’s see why.
Cts and pfizer positions on the times after the first doseHema’s cavalry marches said at the press conference that “the administration of the second dose of pfizer biontech was expected up to 42 days. The medical director of the pharmaceutical house in marine valeria reiterates the concept: “the vaccine was studied for a second administration at 21 days”. What is written in the vaccine liarin the liar we actually read a hint at the 42 days, however it does not seem very representative.
Refers to the 2/3 phase clinical trials of a total of 44 thousand volunteers, of which 93% received the second dose between 19 and 23 days from the first. Only the remaining 3% would probably be a time gap between 24 and 42 days. “In phase 2/3, some 44,000 participants were randomized in numbers equal to receiving 2 doses of anti-COVID-19 mrna vaccine or placebo, 21 days away.
In the efficacy analysis, participants were included who received the second vaccination at a distance of 19-42 days from the first. Most (93.1%) of those who had received the vaccine received the second dose from 19 days to 23 days after dose 1». In clinical tests, it is always 21 days between first and second dose.
What the WHO saysin the WHO report that refers to all data available until December 22, 2020, we talk about the same time. The term “42 days” never appears. Not less, in the part concerning the programs recommended by the producer we talk about intervals of 19-45 days, from which emerge the 21 recommended in general by pfizer.
«Pfizer-BioNTech COVID-19 bnt162b2 (30 micrograms) vaccine is intramuscularly administered as a series of two 30 microg doses of diluted vaccine solution (0.3 ml each) according to the following diagram: a single dose followed by a second dose 21 days later. The interval between the two doses in the study included 19 to 45 days. A sentence was added with the information that 93.1% of these participants received the second dose from 19 to 23 days after the first dose.
There are currently no clinical data on the effectiveness of the vaccine when administered beyond the intervals used in clinical trials”. What the last ministerial circular saysthe circular of May 5 of the Ministry of Health admits that the interval for pfizer is 21 days. According to the same document the second dose within 42 days (and not beyond) is “possible”.
We therefore talk about a period of tolerance beyond which it would be better not to go. The interval between 19 and 42 days has actually been contemplated in clinical trial, no less the effectiveness after 19-23 days from the first dose concerns 93% of inoculated subjects. Cts therefore speaks of ‘internal’ administration an optimal time span of 42 days, beyond which we have no scientific evidence of a better effectiveness.
On the other hand, pfizer is not required to have all statistical data on pandemic in Italy. No one at the ministry or at the cts seems to state that from now on the administration of the second dose will be carried out exclusively at the stroke of the 42nd day from the first. With a vaccine that guarantees more than 80% effectiveness from the first injection, it was considered possible in Italy a certain elasticity within and not over 42 days from the first dose.
Cover photo: ANSA/VALDRIN xhemaj | a medical staff prepares a dose of Pfizer-BioNTech COVID-19 vaccine at a vaccination center in pristina, kosovo, 11 may 2021.read also: