A third round of vaccinations is one of the proposals to address the reduced efficacy against the variants.

Mass vaccination in Seville.

Since the beginning of the epidemic of SARS-CoV-2 By the end of 2019, tremendous efforts have been made on a global scale to investigate the genetic variability of the new coronavirus. This has made it possible to identify different variants considered to be of interest to public health, as they are associated with greater transmission capacity and having displaced the rest of those that previously circulated in a specific territory.

Among these variants, the ones that are of most concern now are B.1.1.7, B.1.351 and P.1, described for the first time in the United Kingdom, South Africa and Brazil, respectively. Although at this time it is difficult to estimate its real frequency in our country, variant B.1.1.7 is the one that seems to be circulating most frequently throughout Spain.

Spain has already started vaccination with the products of Pfizer-BioNTech, Moderna and the University of Oxford / AstraZeneca, and in a few weeks it will do so with that of Janssen. With these vaccines they look for stimulate the immune system, so that it produces both specific antibodies that protect us from infection, and cells that prevent the development of the disease.

In addition, it is intended to achieve an immune memory, which helps the body respond quickly and specifically if infection by SARS-CoV-2 it ends up being produced. This memory depends to a large extent on the production of the type of antibodies called neutralizers.

Resistance to neutralizing antibodies

Pfizer has published a recent study showing that its vaccine stimulates the production of effective neutralizing antibodies against the variants of concern, although they detected a lower capacity to neutralize the B.1.351 and P.1 variants compared to B.1.1.7 and the Wuhan variant (the first sequenced). Other studies seem to confirm a marked resistance to the neutralization of variant B.1.351 in individuals who have received vaccines from Pfizer, Moderna and AstraZeneca.

Results from clinical trials in South Africa of other vaccines, such as Novavax Y Johnson & Johnson, also show a reduction in efficacy compared to variant B.1.351, from 80-90% efficacy to around 60%.

It is especially worrying the second wave of infections associated with the P.1 variant observed in Manaus, a Brazilian city where 76% of its population had already been infected by other variants during a first wave, generating an immune response that a priori would not be as effective against the new variant.

Faced with this situation, most pharmaceutical companies have assured in press releases that they are taking a proactive attitude to maintain the efficacy of their vaccines against these variants. Modern has proposed two strategies: a third dose to further increase the antibody titer generated against SARS-CoV-2; or the production of a new vaccine to deal with variant B.1.351.

Maintain individual protection

In any case, as long as it is not possible to control the levels of virus circulation – especially now that only a low percentage of the population is vaccinated – it is likely that new variants of interest for public health arise, such as the one recently observed in the United Kingdom in 35 cases combining the mutations of variant B.1.1.7 with the typical E484K mutation of variants B.1.351 and P.1 and which the British government already regards as worrying.

For this reason, it is of vital importance at this time both the control of the dissemination of the virus while maintaining individual protection measures —use of masks and social distancing—, how to increase vaccination rates globally.

* Francisco Díez-Fuertes He is a researcher at the National Center for Microbiology of the Carlos III Health Institute (ISCIII), in the AIDS Immunopathology Unit.