90% of the population over 12 years of age, 38 million people, carry the complete schedule of the covid vaccine in Spain, most of them two doses, one if it was from Janssen. Almost half of those people, 17 million, have had another booster injection. Now, the third dose begins to be administered to those under 40 years of age. The fourth will be injected into immunosuppressed people and it will be studied for those over 70 years of age. Is the effective strategy to vaccinate every five months? Does it involve risk? Immunologists have reservations about such revaccination. “It may not be bad, but it is not necessary either,” summarizes Eva Martínez Cáceres, vice president of the Spanish Society of Immunology (SEI).
Remember that the SEI took a position in December: immunologists were against generalizing the third dose, but the entity said that the new omicron variant “justifies it to a certain extent, especially in adults. However, given the demonstrated efficacy of the vaccines, there is no evidence that a fourth dose should be administered in the near future.” The Ministry of Health and the autonomies revaccinate because (although they have not given data), the injections lose efficacy against ómicron and the third dose recovers the level of protection up to around 75% (according to some studies, ómicron drops to 34% the efficacy of Pfizer after 15 weeks and nullifies that of AstraZeneca after 10). In transplant recipients and other immunocompromised patients, the vaccine efficacy is already lower, hence the fourth dose.
video-caption-title ">The vaccination strategy to administer the third dose continues. After the authorization for those over 40, now the Public Health Commission of the Interterritorial Health Council has decided to inject a new dose to adults up to 39 years of age (about 12 million citizens). This was indicated by the Minister of Health, at a press conference in which she forgot to comment that the aforementioned commission had also approved a fourth dose for people in a situation of great immunosuppression, some 120,000. They will all be given Pfizer and Moderna (mRNA).
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Immunologists fear that it will be generalized as the third, when they believe that the priority is for the maximum population to take both doses and some three million Spaniards have not yet done so. There will be a hypervaccinated population and another without coverage, in Spain and in the world in general.
Martínez Cáceres, who is head of immunology at the Germans Trias hospital in Badalona, affirms that the first two doses have helped a lot, but questions “if it makes sense” to continue injecting the same vaccine (those with mRNA from Pfizer and Moderna) designed against the first variant of the virus. “Yes, they would make sense against different variants or parts of the virus to amplify the immune response,” he indicates. The approved ones are against protein S. This would change if, in March, Pfizer has reformulated its vaccine against omicron.
“Vaccines against different variants or parts of the virus would make sense,” says Eva Martínez Cáceres
Another issue is that it was said that, when contracting covid, the second dose was not necessary until after six months. Now, the third is put on five months after the second and a month after passing the infection, those over 65 years of age, right away. It is not known what amount of antibodies protects, because another mechanism of cellular immunity also acts but, when the infection passes, a strong immunity is acquired, which in some studies has been seen to last six, nine, perhaps more months. It is greater the more serious the infection has been and it is reduced before ómicron, but Martínez Cáceres does not understand why that immunity is not taken into account before the third dose. It would not be so urgent to put it on. In fact, he doubts the need for so many injections in general, reinforcement would be necessary for those who do not respond well to the two doses. That would exclude healthy young people, with a very reactive immune system (it weakens with age). But warn anyone who thinks, I don’t get vaccinated, to get infected and immunize: they have a higher risk of long-term effects of covid.
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Regarding the fourth dose to immunocompromised patients, he understands that they want to increase their protection, although he fears that “if there was no good response with the first three, there will not be a good response to the fourth”. The ideal, he says, would be to analyze the immunity of each person to see who needs an additional dose, to protect the most vulnerable.
Can so many injections cause harm? Martínez Cáceres assures that no. But giving the vaccine every few months, if that’s going to be the strategy, can cause the immune system to tolerated , and would lose effectiveness. Marco Cavalieri, head of vaccines at the European Medicines Agency, expressed that concern a couple of days ago, in addition to warning about citizen fatigue.
Magda Campins, an epidemiologist at the Vall d’Hebron hospital, points out that with most vaccines it is not seen that they damage the immune system by giving them repeatedly. Only with some polysaccharides has immune tolerance been given, but they are not the type used against covid. Instead, he says, the third and fourth doses have been seen to increase the level of antibodies.
“We are rushing excessively”, says the epidemiologist López Acuña
“We are rushing excessively, I would not go to a fourth generalized dose, I see the third as premature until 18 years of age. To think that the solution is to vaccinate every few months… I think the authorities decide a little to show that they are doing something,” says epidemiologist Daniel López Acuña, who was a director of the World Health Organization (WHO). He thinks it would be better to wait to reformulate the vaccine.
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