Annual antiCovid revaccination may not be necessary if the virus does not begin to become more pronounced than it has been so far. Three different studies on the duration and effectiveness of vaccine protection confirm that dual injection-activated protections can last for years, that mixed vaccination appears to provoke an increased response, and that, if needed one day, third doses they will prominently awaken antibodies and other immune cells.
The first paper, published in Nature, confirms the ability of the human immune defense to keep pace with the virus’ ability to evolve. Immunologists at the University of Washington at St. Louis found that 15 weeks after the first dose of Pfizer and Moderna mRNA vaccines, B lymphocytes (immune cells that produce specific antibodies) in the lymph nodes were still in the body and were in full activity: instead of shrinking after 4 or 6 weeks, as it was thought it could happen, they become more and more sophisticated and learn to recognize new viral sequences by adjusting their weapons against coronavirus variants.
The longer these cells are “trained”, the wider and more stable the protection they provide. People immunized with dual mRNA vaccines can be protected for years (excluding immunocompromised patients or the elderly).
A second paper by scientists from Oxford University confirms that mixed vaccination produces a strong immune response and can improve the impact of the vaccination campaign against the spread of the virus. According to researchers who have long been investigating the effects of different combinations of vaccines on the immune system, the amount of antibodies generated against the coronavirus varies depending on the vaccine regimen followed. Two doses of Pfizer produce higher levels of antibodies, but one dose of AstraZeneca vaccine followed by one dose of Pfizer generates a response of virtually the same magnitude (while other combinations would seem less effective).
Mixed vaccination, the effects of which still remain to be investigated in greater numbers, also appears to have a significant impact on T cells, charged not with directly inactivating the virus as antibodies do, but with finding and destroying infected cells. The combination of a dose of AstraZeneca vaccine and a Pfizer appears to provide the strongest activation of these lymphocytes.
All of these findings seem to refute the hypothesis of an anti-Covid vaccine booster for everyone in the near future.. If a booster is needed, it will be because of the variants and not because of the depletion of the immune defense. However, we are preparing: a third study conducted on 90 British volunteers who had received a double dose of the AstraZeneca vaccine in recent months showed that a third booster dose actually increases the response to the coronavirus. In volunteers who had received the second dose 30 weeks earlier, the vaccine increased antibodies to levels reached one month after the second injection, and also increased T lymphocytes (Focus, scan).
