After watching with suspicion our British neighbors extend this period, we finally follow suit, in order to be able to vaccinate more people faster. Forget the strategy of securing the second dose, or taking the time to vaccinate only the most vulnerable, as advocated by HAS ! We will manage the vaccine doses delivered on a just-in-time basis.
Normally, at the end of January, we should have vaccinated residents of nursing homes and nursing staff over 50 years old. This represents a little over two million people. According to the vaccine ordering schedule, presented by the government on Thursday, January 7, this is precisely the number of doses that we will have received at that time. Postponing the second injection by a few weeks therefore makes it possible to wait for additional deliveries (provided that the AstraZeneca vaccine is approved in January), while starting to vaccinate people over 75 years old. There, that represents five million people in France.
The first to worry about this lag is the manufacturer Pfizer since he combined his vaccine to be 95% effective with two doses three weeks apart. With one dose, it is only 52% effective. But these tests also showed that ten days after the administration of the first dose, there is already a very protective effect of the vaccine. The second dose mainly helps to make the protection last longer.
The protocol provided for a window between 19 and 42 days to administer the second dose. For’Medicines Agency who gave his opinion on the subject last night, so there is no risk in going up to this deadline. And it also assumes that the protective antibodies do not abruptly reduce between the 21st day and the 42nd. Like the WHO, she now believes that there may therefore be some flexibility, except for very old people with weaker immune systems.
The agencies recognize this, they concede this flexibility because of the more contagious variants and to compensate for possible shortages. This agitates the scientific sphere : especially when our English neighbors plan to extend the time to three months or to mix an injection of Pfizer with an AstraZeneca. A act of despair facing the epidemic for some scientists, since this has not been studied in clinical trials.
The United States remain cautious but according to the New York Times, the US National Institute of Health is testing the effectiveness of Moderna’s vaccine with a single dose. A crisis strategy that also shows that after fearing that people will not get vaccinated, governments now fear that there are not enough vaccines for everyone.