A British study found that a mixed approach to immunization against Covid-19, using different vaccines for the first and second doses, offers good protection against the virus. what emerges from an experimental research carried out by the scholars of the Com-Cov project at the University of Oxford on a sample of 850 volunteers, all over 50. This was confirmed to the British press by Professor Jonathan Van-Tam, deputy chief medical officer of England.
I study
The Com-Cov study, also cited by the BBC, among others, evaluated the effectiveness of different vaccine combinations: two doses of Pfizer, two of AstraZeneca, one dose of one and one of the other. All combinations have been shown to be effective in activating the immune system, but there are differences.
According to the data – illustrated by Professor Matthew Snape, head of the experiment – in the sample studied the best results in terms of antibodies registered with the Pfizer double dose. Looking instead at the levels of T cell – the first line of defense of our immune system, the one that manages the virus attack – a first AstraZeneca dose followed by a second Pfizer would seem to guarantee the highest ones ever. Slightly less effective, however, is the reverse use of a first Pfizer dose followed by a booster with AstraZeneca. The immune effect of the latter combination was however positive and on average better than the two doses of AstraZeneca.
The third dose
The study results therefore suggest that people who have already received two doses of the AstraZeneca vaccine may have a stronger immune response if they then received a different third booster dose, if recommended, in the fall.
British data and the Delta variant
Beyond this experiment, still relatively limited in numbers, there are data on the British situation, which show the effects of administering tens of millions of doses of AstraZeneca and Pfizer in the United Kingdom. As Snape points out, these are numbers that testify to a very effective impact against serious infections from Covid both of the double dose Pfizer and the double dose AstraZeneca. In particular, the reduction in hospital admissions is very large, even in the cases of the Delta variant.
June 28, 2021 (change June 28, 2021 | 21:12)
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