The discovery in a study conducted by the University of San Diego in collaboration with the Irccs San Martino of Genoa. The research, analyzing the response of T cells against all variants of the SARS Cov-2 virus identified so far, has shown for the first time that the latter do not reduce the immune response guaranteed by the Pfizer, Moderna, Johnson & Johnson, Novavax vaccines, which remains durable and effective even six months after vaccination.
14 FEB – The variants fail to ‘break through’ the protection of vaccines, which continue to shield us against the virus for a very long time because in addition to antibodies, they stimulate the formation of T cells, immune system cells with “iron memory” that know how to ‘unmask ‘and fight the virus even when it changes face thanks to mutations.
These cells, capable of re-igniting the immune response in a very short time, persist in circulation for a long time, maintaining a reactive response against all variants after 6 months from vaccination, on average equal to about 87-90%, which barely drops to ‘ 84-85% for Omicron alone, compared to the initial post-vaccination one. They are the key to long-lasting immune protection, which protects against severe disease for a long time regardless of possible future mutations of the virus.
These are the results that emerged from a study published in the journal Cell by a research team of La Jolla Institute for Immunology in San Diego, driven by Alessandro Settedell’University of California in San Diego, in collaboration with Professor’s group Gilberto FilaciDirector of the Biotherapy Unit of theIrccs San Martino Polyclinic Hospital in Genoa and full professor of technical sciences of medicine and laboratory of theUniversity of Genoa. “The study allows us to predict that vaccine-induced immunity is very prolonged as well as likely effective against future variants as well. The booster dose is confirmed as the best method to ‘call back’ other memory T cells, strengthening our line of defense against the virus ”, explains Gilberto Filaci.
The immune system and the virus. The army of the immune system is divided into two great ‘legions’ that contribute to an effective immune response. The first is linked to the activation of B lymphocytes, responsible for the production of antibodies that are like missiles, capable of recognizing and killing cells infected by the virus. The second is linked to the activation of T lymphocytes, immunological memory cells that persist for a long time even after a possible decrease in antibodies, as occurs in subjects vaccinated against Covid in which there is a decrease in antibody levels already within six months after vaccination. “These cells are like perennial sentinels capable of recognizing an enemy after years and years from the first meeting and of mounting in a very short time an immune response that reactivates the production of specific antibodies: those that then bind to the virus, preventing or resolving the infection – Filaci specifies – thus, the specific ‘memory’ T cells, which are formed after coming into contact with a germ, by contagion or through vaccination, persist in the circulation, protecting us from it every time we meet it: they do this also through the immediate reactivation of the antibody response, thus generating a sort of immunological ‘double shield’, essential for long-lasting protection “.
The study analyzed the T cell response It has been shown that they recognize all ten different variants that have emerged in recent months, including Omicron, and remain capable of giving an effective immune response even 6 months after vaccination. Analyzing the T cells of people vaccinated with 4 different vaccines (Pfizer-BioNTech, Moderna, Johnson & Johnson / Janssen and Novavax), the researchers observed that the reactivity of T cells at six months is in fact on average 87-90% compared to the initial post-vaccination rate and drops to just 84-85% against Omicron, regardless of the vaccine received.
“The immunity induced by T cells is therefore lasting and significant against all known variants and is not ‘pierced’ even by Omicron – explains Filaci – when a vaccinated person comes into contact with the virus, even months after vaccination. , the T lymphocytes rapidly stimulate the B lymphocytes to produce specific antibodies: in this way a ‘double shield’ is created to the virus almost immediately and the infection is promptly fought and eradicated in a much faster time and with a much greater efficacy than what can happen in the unvaccinated.
Also for this reason, although vaccinated people can still become infected, they generally have mild or even asymptomatic forms of the infection. Given the results of the tests 6 months after the vaccine, it is very likely that the T cells of the vaccinees give rise to long or very long lasting immune protection against serious disease; however, the booster dose remains very important to further minimize the very slight decline in T cell response observed six months after vaccination. Finally, it is plausible – adds Filaci – that the vaccine can also ‘slow down’ future variants: the study found that the T cells of each vaccinated individual recognize on average about twenty different pieces of the virus, generating a redundant, that is, direct immune response. against more than one fragment of the spike protein: this makes it less likely that the virus will generate future variants in each of these twenty bits of molecule, such as to make it totally unrecognizable to T cells ”.
Another young Italian researcher participated in the study with an important role, Alba Grifoni, and the American doctor Alison Tarke, with a PhD in Clinical and Experimental Immunology from the University of Genoa. “This study – said the rector Federico Delfino – it is also an example of how virtuous and productive collaborations and synergies between local and international bodies can be in scientific research and demonstrates how our PhD courses, if managed with an international vision, can lead to the generation of brilliant young researchers, our hope for the future”.
“The pandemic emergency has confronted the scientific community with the need to prepare rapid and effective responses through collaborative efforts between different bodies at national and international level – underlines Antonio Uccelli, Scientific Director of the San Martino Polyclinic Hospital – this study is a prime example and demonstrates the ability of the Genoese institutions to work synergistically with some of the best researchers in the field of Covid research “.
February 14, 2022
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