After a threat last month to suspend vaccination with the Oxford University formula, AstraZeneca, this week everything was blown up. After the European Medicines Agency (EMA) concluded that there was evidence of a relationship between very rare cases of thrombi in inoculated people, the Public Health Commission decided to continue vaccinating with AstraZeneca, but only to patients between 60 and 69 years old. In Spain, more than two million people have already received the first dose. What will happen to them? Is it worth continuing to administer this vaccine? Is thrombosis a common side effect? Víctor Jiménez Cid, Professor of Microbiology at the Complutense University of Madrid, responds to the most frequent doubts generated about vaccination in recent days.
One of the main questions that citizens ask themselves is: What is happening with the AstraZeneca vaccine?
There is too much noise, much more than there should be. It is an issue that concerns us all because vaccines are the main solution to this enormous global health problem and society demands information. We have several already approved vaccines of different characteristics. All are effective and all are safe because they have been approved after phase III clinical trials, which is what every drug requires for distribution.
From there, it enters a phase IV of pharmacovigilance in which the product is on the market and its side effects continue to be monitored. In this phase, a serious side effect of the AstraZeneca vaccine has been reported that was not noticed in phase III.
Why hadn’t it been seen in that previous phase?
Because in phase III the trial is done on tens of thousands of people (around 30,000 in COVID-19 vaccines). If the problem had been detected at this stage, it probably would not have been immediately approved by the Food and Drug Administration (FDA) and the EMA. If it was approved, it is because it was assumed that, if there were any undetected minor or serious side effects, it would be very rare (greater than one in 30 or 50,000), a risk that is usually assumed in excess. Any drug on the market can cause potential serious side effects as frequent or more frequent than this vaccine.
Is the risk-benefit balance worth it?
We have an important urgency to achieve a good population immunity and solve the pandemic situation, from the health, economic point of view, etc. The priority must be to vaccinate all of us as soon as possible, and vaccines are effective, including the one from AstraZeneca . That should be what we should prioritize.
One in 100 people diagnosed with COVID-19 CRP dies. If we have an incidence of one in every half a million thrombosis, the benefit outweighs the risk. What happen? That since there are other vaccine alternatives that generate less doubts, people wonder why it is their turn to get vaccinated with AstraZeneca.
I understand the concern, but they have to weigh it up and see that the probability of suffering serious complications is very remote and its danger is minimal if we compare it with that of contracting the disease.
Finally, it was decided to keep the vaccination in the 60-69 age group. Why?
If we decide that those over 60 should now be vaccinated with the AstraZeneca vaccine, we must explain well why, so that the population understands it. It must be explained that the rare thrombotic complication has not been detected in this age group, since it has an autoimmune nature and the immune system at that age is less aggressive.
The fatality rate of the virus in people between 60 and 70 years is 5%, that is, one in 20 can die if they do not get vaccinated, while the frequency of this side effect of the vaccine is one in 100,000.
What do you think of the options being considered, such as leaving those vaccinated with AstraZeneca with only one dose or combining with another vaccine for the second?
There is a lot of confusion. A single dose already supposes a certain level of protection and, if there is no more possibility of using this vaccine, it can be left. The Janssen vaccine is similar, and since the clinical trials were done with a single dose, that is the regimen that is used.
The least realistic option is to combine different vaccines for the second dose. It is not that it cannot be done, it is that for it to be carried out we will have to wait for the results of clinical trials that show that the mixed regimens are safe and effective, and that will take time. My recommendation is that the guideline be completed. If the first dose has not caused autoimmune complications, it is difficult for them to occur on the second.
So far, the rate of thrombosis as a side effect by number of vaccinated, is it normal, compared to other drugs, or more worrying?
It is difficult to know, it is something new. This type of side effect (cerebral venous sinus thrombosis) has not been associated with any vaccine so far, neither against other infections nor among the other vaccines against COVID-19, which are not without side effects either. However, a mass vaccination campaign had never been carried out in such a short time.
If it had been carried out with previous vaccines, we would have found things like this or worse. I am in favor of vaccinating with what we have as soon as possible because the urgency is to stop the pandemic. I am the first to say that, if we had unlimited availability of all approved vaccines, indeed, this vaccine would be reserved for population groups for which there is no risk. But in the end, the priority is to vaccinate and this side effect is extremely rare. More uneasiness is created by these rudder changes. It is very difficult to educate the population so that they understand the benefits of vaccination with all these changes in decisions, especially if they are explained by politicians. It is not easy, in any case.
How is so much change of opinion on the part of the authorities justified?
It is a question of who exercises responsibility and who then has to account for the decisions they have made. If someone dies from side effects of the vaccine, it will be reported to the health authorities. But, sometimes, there is an excess of prevention. For every day that you stop the vaccination campaign, you will have X infections that will translate into X deaths. We have been with more than a hundred deaths a day for months and that adds up and adds up. To stop it, in addition to prevention with tests and hygienic measures, the key is the vaccine. If before the slightest doubt, as happened two weeks ago, we stop the vaccination campaign, the prevention of many fatal cases is avoided.
How can scientists restore confidence to the population lost these days?
Scientists are not communication professionals, the media are, who are carried away by the hunger for headlines. It is very difficult, in this scenario, to give a message of good sense because the truth is that we are all in an experiment in real time. It is not that scientists are experimenting with the population, it is the virus that has spread, it takes our pulse and we learn as we go. You have to send a message of serenity and explain why decisions are made, to what extent there is danger or if the benefit is greater than the risk. It also helps to give examples. The birth control pill, used by so many women, has a much higher risk of thrombosis than the AstraZeneca vaccine. Some anti-inflammatories also have significant side effects and are used often.
And we assume the risk of taking them …
We assume it. In this circumstance, what is more important to us, to get out of this situation? In Madrid, 2 or 3 people out of every 100 who become infected will die. We are going to vaccinate. At what price? That one person in every 100,000 suffers a vascular accident, which is fatal in 1: 1,000,000. But, I insist, many more will die if we do not accelerate vaccination. This shadow now weighs on this vaccine, but it is still a good vaccine.
María Milan García, Researcher of the project “Scientific Communication and Dissemination in the Transfer of Knowledge in the University”, Complutense University of Madrid
This article was originally published on The Conversation. Read the original.
