Covid, second dose booster of a different vaccine? Commissioner Figliuolo opens the possibility: “It seems that they give an excellent answer”

The possibility of administering has been discussed for several weeks a second dose of a vaccine other than the first dose. The problem arose when the case of the rare cases of thrombosis induced by the Astrazeneca vaccine broke out. Meanwhile, studies have started in some European countries to test the mix. Great Britain is the leader of the experiment, but also a Spanish studio has recently confirmed the “goodness” of the mix. And it is to these researches that the Commissioner for the Emergency is probably referring Francesco Figliuolo answering a question during the episode of Elisir on Rai 3. “There are advanced studies on the second heterologous dose, that is, making the first dose with Astrazeneca and the second with Pfizer O Modern“And” it seems that they give a great answer“. In some countries such as France and Spain the second dose for under 60s is provided with a different vaccine even if they are given the possibility of boostering with Astrazeneca anyway.

The position of the Ema – The European Medicines Agency also expressed itself a few days ago on this point. The possibility of mixing different vaccines between first and second doses “is a very important issue that is under discussion now. There are some data regarding this possibility, in particular with AstraZeneca and an mRna vaccine “ for the second dose. “One study has been conducted in the UK and another is expected to yield results from Spain. But there are no particular concerns from a safety point of view and even the few data we have seen show that even in terms of immunogenicity it seems an effective approach to generate a robust immune response after a second dose of different vaccine. However, we are trying to collect more evidence and review the studies to be sure that this approach is as good as it seems ”explained Marco Cavaleri, Ema’s head of Vaccines and Therapeutic Products for Covid-19.

The British and Spanish study – Here’s what the known studies say. The use of a mix of anti Covid vaccines (AstraZeneca and Pfizer) – tested in Great Britain – appears capable of produce a slightly higher frequency of non-serious “short-term” side effects, but it does not involve “safety concerns” for people. The results come from the preliminary test conducted in the United Kingdom by the researchers of the Com-Cov dell ‘University of Oxford on 830 volunteers aged 50 and over up an excerpt of which was published in a letter sent to the Lancet. The Oxford University project – launched in February – was extended to also study the interaction between Moderna and Novavax injections (the other vaccines the country has stocked up) with the declared intent to understand if the mix of vaccines can promote longer periods of immunity to the virus.

The study – on the use of the messenger RNA vaccine and the viral vector vaccine – did not verify substantial differences between the administration of a first AstraZeneca dose and a Pfizer booster and the reverse. Reactions noted as more frequent than the use of a double dose of the same vaccine, with one or the other serum, they concern phenomena such as headache, fever or fatigue: ie basic side effects, usually limited to one day, and described as “mild” (mild) or at most moderate. “Our results – one of the trial coordinators, Professor, explained to Sky News Matthew Snape, pediatrics and virologist at Oxford – indicate that mixing doses may entail an increase in absences from work by one day after immunization. But it is important to note that there are no safety concerns (of patients) and there are no signs of an impact on the immune response. ” As if to say, that the effectiveness of the crossing of the two serums does not appear lower than that guaranteed by a normal double dose of the Pfizer or AstraZeneca vaccine.

A clinical study byCarlos III Health Institute, a Spanish public body, concludes that giving Pfizer’s anti-covid vaccine as a second dose to people who have received the first of AstraZeneca is safe and increases the immune response. The project managers explained this in a press conference reported by the Iberian media. “We can only conclude that administering a booster dose is highly immunogenic and safe,” he summarized Jesus Antonio Frías, one of the researchers in charge of the study, in which they participated 673 volunteers (221 as a control group). Frías added that the “adverse reactions” found are “similar to those in cases where a single vaccine was administered” and “in no case serious”. This week, a decision is expected from the Spanish health authorities on how to proceed with people who are under 60 and have received a dose of AstraZeneca before it was decided to continue with this drug only with the over 60s.

The immunologist Abrignani: Mix can be beneficial “-” What we expect is that the immune response “induced by mixing different types of anti-Covid vaccines, in particular an adenovirus vaccine such as AstraZeneca with a messenger RNA such as Pfizer / BioNTech or Modern, “is at least the same or even better” dice Sergio Abrignani, immunologist at the State University of Milan and member of the technical-scientific committee for the coronavirus emergency, which expects data to confirm this “by the summer”. The answer could come “from the Cov-Boost trial underway in England”. The issue returned to the spotlight after the president of the Italian drug agency Aifa, Giorgio Palù, declared that “two different vaccines induce a much more effective immunization, with antibodies 10 times higher than those have with the same administrations “. And a solicitation to express himself on this point was addressed to the European Medicines Agency Ema by Prime Minister Mario Draghi. “Immunologically, and I speak as an immunologist – says Abrignani – have a priming of the immune response with a vaccine type and a booster with another type, generally, based on what we know about other vaccines “against diseases other than Covid-19,” in terms of immune reaction it is at least the same and often even more advantageous. Indeed – he specifies – with certain types of adenoviral vaccines “not Covid,” it is really recommended to do the booster with a different product. It was already seen 15 years ago that priming with an adenovirus-based vaccine, which is itself immunogenic or recognized by the immune system, is much more advantageous if the booster is then done with a different vaccine, for example with DNA such as had happened in those searches “. In short, “the ‘prime-boost’ technique, priming and booster, with two different vaccines has already been widely tested. And even with these anti-Covid vaccines “, with the mix” what we expect is that the answer is either the same or better “.

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