Changing the second dose of a vaccine on the run to a different one – as Germany decided to do with those who had taken the first dose of AstraZeneca – may not be a good idea. According to a study by the University of Oxford – in fact – there are more chances of mild and moderate side effects in adults after the AstraZeneca and Pfizer mix. Nothing serious, of course, but chills, headaches and muscle aches are the most frequently reported side effects, however short-lived.
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“It is a very intriguing and unexpected discovery,” he said Matthew Snape, of the Oxford Vaccine Group. The Com-Cov study began in February with the aim of verifying whether a different vaccine for the second dose could lead to longer-lasting immunity, better protection against new variants, or simply allow better use of available stocks. , even if of a different type.
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The study recruited 830 volunteers over the age of 50. Preliminary data (the complete ones will be published in June) have been communicated on Lancet in detail: fever four weeks after the administration of two doses of the AstraZeneca vaccine in one in ten people. Worse results for combined AstraZeneca and Pfizer administration: 34 percent mild side effects. “The same differences apply to other symptoms such as chills, fatigue, headaches, malaise and muscle aches,” Snape added. In April, the study was expanded, adding another 1,050 volunteers and this time different combinations will be tested: Moderna and Novavax together with AstraZeneca and Pfizer. In any case, someone – the Canadian provinces of Quebec and Ontario to begin with – has already said that they will use different types of vaccines for the first and second doses, both to avoid delays due to shortages of supplies and to worry about the rare cases of thrombosis. related to AstraZeneca.