The protection of vaccine it is (almost) total. The variants in fact, they fail to «pierce» the protection of anti-Covid vaccines, which continue to shield us against virus maintaining a reactive response against all variants after 6 months from vaccination, on average equal to about 87-90%, which drops to just 84-85% only for Omicron, compared to the initial post-vaccination one. This is the good news that comes from the results of a study published in the journal “Cell” by a research team of the La Jolla Institute for Immunology, led by Alessandro Sette, of the University of California at San Diego, in collaboration with the group led by Gilberto Filaci, director of the Biotherapy Unit of the Irccs San Martino Polyclinic Hospital in Genoa and Professor of Technical Sciences of Medicine and Laboratory of the University of Genoa.
Vaccine, shield and protection
In fact, the study showed that vaccines, in addition to antibodies, stimulate the formation of T cell of memory they know “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, are the key to long-lasting immune protection, which protects against severe forms of disease for a long time regardless of possible future mutations of the virus. «The study allows us to predict – explains Filaci – that immunity induced by vaccines is very prolonged as well as probably also effective against future variants. The booster dose is confirmed as the best method for “call to fight” other memory T cells, strengthening our line of defense against the virus. ‘
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The army of the immune system – the researchers explain – is divided into two big ones “legions” which 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 – explains Filaci – 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 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 double immunological shield, essential for long-lasting protection ».
The study analyzed the T cell response and demonstrated 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.
T-cell-induced immunity is therefore long-lasting and significant against all known variants and does not come “piece” not even from Omicron – explains Filaci – When a vaccinated person comes into contact with the virus, even months after vaccination, the T lymphocytes quickly stimulate the B lymphocytes to produce specific antibodies: in this way a double shield to the virus is created almost immediate 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 get infected, they generally have mild or even asymptomatic forms of the infection ».
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«Given the results of the tests 6 months after the vaccine – underlines the researcher – it is very likely that the T cells of the vaccinated 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 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 immune response, i.e. directed against more than one fragment of the virus. spike protein and this makes it less likely – explains Filaci – that the virus will generate future variants in each of these twenty small pieces of molecule, such as to make it totally unrecognizable to T cells ». Another young Italian researcher, Alba Grifoni, and the American Alison Tarke, enrolled in the research doctorate in Clinical and Experimental Immunology at the University of Genoa, participated in the study with an important role. “This study is also an example – underlines the rector Federico Delfino – of how virtuous and productive collaborations and synergies between local and international bodies can be in scientific research and demonstrates how our doctoral courses, if managed with an international vision, can lead to the generation of brilliant young researchers, our hope for the future “.
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THIRD DOSE – Side effects after administration of the third dose vaccine against Covid are less frequent than those found after the second dose. This is what emerges from an analysis conducted by researchers from the Centers for Disease Control and Prevention (CDC) and the American FDA published in the weekly bulletin of the CDC. The study took into consideration the reports received through a special platform made available to healthcare professionals and American citizens to collect data on Covid vaccination (called v-safe). 721,562 reactions reported; 88.8% of the cases were people who had undergone a similar vaccination course. Overall, the data confirm the safety of vaccines: 92.4% of the reports collected are considered not serious, especially headache, fever, arm pain. There have also been 37 cases of myocarditis out of approximately 82 million doses of vaccines administered. Overall, the reduction in side effects after the third dose was observed for each type of disorder and for all vaccines, especially the Modern one, which however represents the one with the highest rate of reports. Specifically, 71.8% of systemic reactions and 64.4% of local reactions were reported after the Moderna vaccine; significantly lower percentages than the second dose, when the values were 81.4% and 78.4%, respectively. Among the vaccinated Pfizer/BioNTech a rate of 64.3% of systemic reactions and 58.4% of local reactions was reported (after the second dose they were 68.1% and 66.7%, respectively). The same trend was also observed for those who, for the booster, received a different vaccine than that used in the primary vaccination (the so-called ‘heterologous’ vaccination). The study found a slight increase in the number of referrals to the doctor due to complaints after the third dose, however the magnitude of the increase (by 0.1% with Moderna and 0.3 with Pfizer / BioNTech ) is so low that it does not cause concern.
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