A Spanish study verifies that both people already infected and those who have received the two doses are capable of blocking it.

A nurse prepares the Pfizer-BioNtech vaccine at the Hospital de la Santa Creu i Sant Pau in Barcelona.  David Zorrakino / EP

A study led by IrsiCaixa has shown that people who have been infected with Sars-CoV-2 and those who have received two doses of the Pfizer-BioNtech vaccine generate antibodies with the ability to block both the original virus and the British variant.

The results of the study, shared in bioRxiv, they also point out that antibodies are refined within the body: Those who passed the infection in the first wave and, therefore, were infected with the original variant of the virus, have a better capacity to block the British variant six months after the infection than at the beginning, IrsiCaixa reports this Monday in a statement.

The center promoted by the La Caixa Foundation is studying the efficacy of antibodies against the variants that exist so far, to understand the evolution of immunity against coronavirus.

Every time it multiplies, the virus creates an identical copy of its genome, and often during this process makes mistakes and introduces random mutations into its own genetic material, leading to new variants.

Mutations can be in different areas of the genome and, therefore, affect multiple parts of the virus; among them, the spicule protein, which when modified may prevent antibodies from binding, compromising the immune system by stopping the infection.

The principal investigator at IrsiCaixa and the Germans Trias i Pujol Research Institute (IGTP), Julià Blanco, has said that at this time of the pandemic It is necessary to understand if the antibodies “can protect against the new variants and how long this protection lasts”.

During the study, the protective capacity of the antibodies of 53 people who had passed the infection and of 32 people who had received the two doses of Pfizer, working with pseudoviruses, viruses produced in the laboratory, some of which have kept the original virus and others have incorporated mutations of interest, in this case the British one.

The results show that infected people block “very well and very similarly” both the original and the British variants, and researchers have found that those infected in the first wave who had generated antibodies against the original variant have a better response against the British variant six months after infection, compared to the start.

They point out that the antibodies produced by the body itself against the original virus are refined over time and improve your ability to block new variants.

Thus, researcher Benjamin Trinité has said that natural infection, compared to the vaccine, generates a better quality immunity against the Sars-CoV-2 because it exposes the different proteins of the virus to the immune system for a long time over time, “and it may also be that parts of the virus remain inside the body that, over time, refine the antibodies.”

As for people who have received two doses of the vaccine and had not passed the infection before, its antibodies are twice less efficient in blocking the British variant than the original, although they are “high enough” to prevent infection by both variants.

People who had already passed the infection and received the vaccine have antibodies that “very efficiently” neutralize the two variants and they even act better against the British.

IrsiCaixa researcher Edward Pradenas has explained that the results show that most people have protection against both variants, but it is not known how long this protection lasts, and there may be people who lose the antibodies, so defend the mask and the distance until there is a very low incidence.