Pfizer and Moderna vaccines may offer immunity for years

A study published in Nature is the first to confirm the presence over time of germinal centers of B cells that ‘train’ antibodies.

Vials of the Pfizer Covid-19 vaccine.

Until now, the immunity generated by vaccines against Covid-19 is measured by ‘weighing’ the amount of neutralizing antibodies, which prevent the coronavirus from binding to the cells it wants to infect, several weeks after receiving the injection. The problem is that antibodies are short-lived and nothing ensures that this amount will not decrease rapidly in a short time.

A new study has shown that there is hope beyond the antibodies generated. It has only been performed on 14 people but has been published in Nature, which gives a clue about the magnitude of his discovery. And it is that, instead of analyzing the amount of antibodies present in the blood of these people, the researchers have looked for another type of ‘traces’ of immunity.

It is about the presence of so-called germinal centers, where B cells differentiate to generate specific antibodies for a given pathogen. The presence of these centers implies the body’s ability to ‘train’ antibodies for a longer time, opening the possibility that immunity from vaccines lasts for years.

The authors of the research, led by Ali H Ellebedyfrom the Department of Pathology and Immunology of the Washington University School of Medicine, have traced through ultrasound the presence of these germinal centers in the lymph nodes, structures present in the body (especially in the neck and armpit) They play a prominent role in the recognition of pathogens by the immune system.

The presence of these germinal centers was maintained 15 weeks after the inoculation of the first dose of the Pfizer-BioNTech vaccine, that is, four months after completing the vaccination schedule. In all vaccinated individuals, a constant presence of B cells that produce specific antibodies for the S protein of the virus (the point of union with the cell to be infected) was found.

The authors note that this is the first study to provide direct evidence for the induction of germinal center-specific B-cell responses following vaccination in humans, “allowing the generation of robust humoral immunity“.

Although the study refers to the Pfizer vaccine, the researchers conclude that this ability to induce germinal center responses is common to those based on messenger RNA. Sera from Pfizer and Moderna were the first to be approved to prevent Covid-19 and have so far shown high efficacy even in preventing transmission of the virus. The few cases of reinfections that have occurred have been mild.

Possibility of regular vaccination

The studies that have been carried out so far determine that the levels of neutralizing antibodies are maintained for at least three months. Those responsible for BioNTech and Moderna have warned, however, that these levels can start to drop six months to a year after the second dose is inoculated, especially in people over 65 years of age. This is the reason why the possibility of regular vaccination in the vulnerable population has been suggested, as is currently established for the flu.

This latest research would give fuel to the idea, increasingly present given the good results that all vaccines are offering (at least, those approved in Europe), that a booster dose will not be necessary in the coming months.

The study led by Ellebedy also offers another perspective, and that is the evaluation of the response of the vaccines against three of the variants of SARS-CoV-2: the majority in Washington at the time of vaccination, B.1.1.7 (known as Alpha or British) and B.1.351 (known as Beta or South African).

This part of the study was carried out with a few more patients and was based on the presence of specific antibodies in the patients’ blood samples, and its conclusions are already known: the levels of antibodies are higher in people who had already passed the Covid-19, in all cases, and the response is less with the South African variant in those people who have not passed the virus.

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