May 13, 2021

“A single dose of AstraZeneca protects against severe Covid-19”



Are coronavirus vaccines safe?

We have to be clear that when vaccines pass the controls of the European Medicines Agency (EMA) it is because they have been shown to be safe. In fact, it is the first thing that is looked at in the authorization procedure for this type of drug. Not even in our best dreams of a year ago we would have dreamed of a situation like the current one, in which we have not one, but several approved vaccines. We have to trust our regulators that we have them for that, follow the instructions and be aware that the only way to get out of this situation is through the protection we acquire through the vaccine.

How can it be that in just one year we have so many effective vaccines against the coronavirus?

Well, it is thanks to the research carried out during the previous 20 years. In fact, we are seeing the differences between Europe and the United States, because the United States has a more oiled system with respect to RNA vaccines (like Pfizer or Moderna). If you have a research network and a powerful pharmaindustry network and also bet on innovation, it is possible. We cannot pretend that all the networks we need to solve these problems will be created overnight because science takes time. It is clear that without prior investigation we would not have achieved this in record time.

What do you think of the decisions that European and American regulatory agencies are making regarding AstraZeneca and Janssen vaccines?

From the Spanish Society of Immunology (SEI) we want to send a message of calm. We know that it is difficult to understand that pharmacovigilance mechanisms work like this, with transparency. These very rare cases are expected to be investigated to really know what the mechanism behind them is. And, if we know how to recognize them and treat them in an early and specific way, we are going to modify the clinical course of those very few cases that may have adverse effects. In any case, we hope it is a temporary matter and that little by little we can use all the tools we have to stop the pandemic.

In Spain it is proposed to leave those vaccinated with AstraZeneca with a single dose, do you see it feasible?

A first dose has been shown to be sufficiently immunogenic to protect us, there are no cases of severe Covid-19 described in scientific publications from the United Kingdom. Therefore, to the people who have remained in that limbo because now they do not meet the age requirement, we urge them to be calm, that they know that they will have a degree of protection that will protect them from serious Covid-19 , which is what it is about. In 12 or 15 weeks a decision will be made about what to do with the second dose, when we have a clearer picture.

And what do you think of the possibility of injecting a second dose of Pfizer, for example?

We believe that we should not put a second dose of a different vaccine than AstraZeneca, until we have data from a clinical trial to support these combinations. It should be remembered that the AstraZeneca vaccine technical sheet specifies that the second dose should be of the same product as normal. In the UK there is a trial underway for these types of combinations and there is probably no problem and it is safe and effective. But we have to wait for the results to decide if we can make these combinations.

Why is the second dose not inoculated when the first is already in place?

What we propose from the SEI is that the second dose of AstraZeneca be given, but we cannot go against the Vaccination Strategy that has set the age limit of 60 years. It is believed that there are 2 million people who are now in that decision limbo.

One of the main problems of mistrust in the vaccine has been the change in inoculation criteria. The population does not understand that in AstraZeneca, before 55 people were inoculated and now they have changed to those over 60.

The EMA never really put an age limit on the use of AstraZeneca. It was the authorities who set an age limit because the AstraZeneca phase 3 trial did not have a large population over 55 years of age. By doing so, we biased these adverse reactions and discovered them in young women under 55 years of age. The United Kingdom did not report these cases before because they did not limit the vaccine, but went directly to inoculate the first dose, prioritizing the very vulnerable population, who are over 60.

All vaccines have rare adverse effects, like any medical device, but it is curious that the production of an aspirin, which has more adverse effects, does not stop and this does.

It also surprises us. I think the difference is that right now the focus is brutally focused on all the adverse effects of vaccines and there is a great magnification of situations that we as scientists, who are used to this type of reaction, are surprised. How things are counted is important, because the population is not used to these types of circumstances.

Vaccines are not reaching the entire planet in an equitable way, which would be the ideal thing to be able to eradicate the disease and avoid mutations, is there a real risk that the virus could elude our vaccine at some point?

What we know today, from studies carried out in survivors and vaccinated, is that the cells have maintained their ability to respond undamaged against all variants. In the case of the serums of people who have passed the Covid-19, a certain decrease was seen, not abolition. I do not know if we will have to revaccinate or if a certain degree of protection will remain, but it is clear that vaccines will absolutely change the panorama we have, because having our immune system with a certain degree of defense, even if it is less, against different types of variants changes completely. the prognosis of infected people. Our immune system works very efficiently and very quickly when we have already recognized the pathogen for the first time. For this reason, I insist that the only way to protect ourselves against the ravages of the pandemic is to get vaccinated.

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