For a few months, the directors of various pharmaceutical companies responsible for the production and marketing of vaccines against COVID-19 have been repeatedly communicating to the media the alleged importance of administering third booster doses to the general population to avoid attenuation of the immune response against SARS-CoV-2. The director of Pfizer, Albert Bourla, reiterated this idea in an interview with the half Business Insider just a few days ago. Bourla explained that “the most likely scenario is that we will need annual revaccination, as we do with the flu vaccine.” Some countries, like Israel, carry and at some time administering third doses to the general population, as a strategy to stop the increase in infections among its population.
How contagious are people vaccinated against COVID-19 who become infected? The reality versus the myths
So far, no pharmaceutical company has applied for emergency authorization of booster doses for the general population from drug agencies, including both the European Medicines Agency (EMA), and the United States Food and Drug Administration (FDA ). However, Pfizer has announced that it expects to complete its request for a third dose later this week.
Apart from the colorful statements to the media by pharmaceutical companies and politicians and the clear economic interests surrounding the booster doses, it is important not to lose sight of the scientific evidence and the opinion of health institutions and experts without conflicts of interest in this question. For now, giving third doses to the general population is not a good idea and these are the current reasons that justify waiting for new studies that really support the need to administer them.
1. No Medicines Agency has authorized a third dose for the general population
Although the statements of certain directors of pharmaceutical companies and politicians suggest that there are already compelling reasons to apply third doses of vaccines against COVID-19, the truth is that there is no solid data in this regard. The EMA reported on August 25 that “it has not yet been determined when a booster dose might be necessary”, nor “which populations should be focused on” in case the need is “confirmed.” According to a representative of the EMA, “emerging data – from the vaccination campaigns underway within and outside the European Union – are still being reviewed to make recommendations that can help” European countries to make a decision on the ” need ”of the booster dose and to whom to direct it.
With respect to the FDA, on August 12 the agency reported in a statement that authorized an additional dose of vaccine, but only for certain immunocompromised individuals due to their special risk of developing severe COVID-19, despite being vaccinated. The FDA further noted that “other fully vaccinated individuals do not need an additional vaccine right now” because “they are adequately protected.”
2. Low levels of antibodies in the blood do not imply immune deprivation
Much confusion and biased data is being transmitted in the media about what it means to detect low levels of antibodies in the blood of those vaccinated over the months. It is absolutely normal for circulating antibody levels to drop over time after receiving a vaccine or passing an illness. The surprising thing would be the opposite. However, the fact that the levels of antibodies are reduced does not imply at all that the person is unprotected against the infectious agent.
We know that cellular immunity plays a much more important role in attacking the coronavirus than humoral immunity (the antibodies) and also that memory lymphocytes continue to remain in the body to quickly and effectively attack the virus if the person is exposed to it again. this. Thus, a person may well have robust immune protection with low or undetectable antibodies. In fact, several studies are showing exactly this phenomenon: although the antibodies generated after the administration of the vaccines are decreasing, the immune memory persists for at least six months.
3. There is no study that shows lack of protection against COVID-19 in the general vaccinated population
Just a few days ago, several media echoed A study which showed that the efficacy of the Pfizer vaccine against the Delta variant was reduced from 90% to 50% at four months. Did this mean that vaccinated people were unprotected against COVID-19 after that time? Not at all, in fact this study also pointed out that the protection against hospitalizations for this disease did not decrease at all in six months. What did they mean then with a 50% efficiency percentage? To the efficacy in preventing SARS-CoV-2 infections among the vaccinated population. However, other studies have not found any attenuation of the immune response to infection months after the vaccines were given, so this is controversial for now.
It is true that very elderly or immunosuppressed people may not respond effectively to the vaccine due to a weakened immune system or unable to respond adequately. It is in these particular cases where an additional dose could be justified to boost, to some extent, the immune response. For this reason, the FDA has authorized a third dose for immunosuppressed patients and it would be no surprise if the EMA would do so as well in the near future. However, the characteristics of these people are very different from the general population where very robust protection against severe COVID-19 is still observed.
4. The top priority to tackle the pandemic is to vaccinate the largest possible population around the world, especially the most vulnerable.
Health institutions such as the World Health Organization (WHO) and multiple epidemiologists have expressed on multiple occasions the need to fight vaccination inequality in the world to stop the circulation of SARS-CoV-2 in all countries and thus protect the most vulnerable individuals, regardless of their country of residence. The concentration of vaccines in the richest countries, while the inhabitants of developing countries hardly receive doses, encourages the free circulation of the coronavirus in the latter, which implies the death of individuals at risk (especially the elderly) and the potential development of new variants that may escape, over time, the protection offered by current vaccines.
That the rich countries insist on third doses supposes to deepen even more in this vaccination inequality. Tedros Adhanom Ghebreyesus, WHO Director General harshly criticized this position: “We understand the concern of governments to protect their populations from the delta variant, but we cannot accept that countries that have already used the majority of vaccine supplies, use even more, while the world’s most vulnerable populations continue without protection”. This health organization has requested a moratorium against the third doses of vaccines: “Vaccine inequity is the greatest obstacle to ending the pandemic and recovering from COVID-19.”
5. According to the evolution of SARS-CoV-2, new vaccines adapted to new variants could be more effective than third doses of the same vaccine
As Public Health experts Daniel López Acuña, Alberto Infante Campos and José Martínez Olmos explain in elDiario.es: “A third dose, with the same type of vaccine that does not include the necessary antigens to neutralize the new variants, will not to provide the protection we need and may lead us to spend efforts and resources without achieving greater efficiency. This has already been clearly stated in the joint statement issued by WHO and the World Independent Advisory Committee on Vaccines a couple of weeks ago. “.
Given that there are, for now, no studies that justify undertaking third-dose vaccination campaigns for the general population, the most prudent thing to do is to continue to monitor and analyze the epidemiological situation carefully. If it begins to be observed that the coronavirus escapes the protection of vaccines, it will be necessary to assess which option is better, whether to use third doses or apply new vaccines adapted to the most prevalent variants in the pandemic.