Protection increases in the weeks following the third dose, but it is unclear how long the effect will last. The first study published in a scientific journal on Israeli data is expected in days. The hypotheses about possible side effects
Does the third dose of Covid vaccine work to prevent disease and infection even better? It seems to be true and expected to be published on the New England Journal of Medicine of an initial Israeli data study, which began the recall program on August 1, involving so far 2.8 million people. So far available to scientists there are analyzes by Israeli health experts and works in pre-print: the publication in an important medical journal, with independent review, will be useful to regulatory bodies such as the American Fda and the European EMA to evaluate the opportunity. of a booster and for which categories.
The data available
A report from the Israeli Ministry of Health (only the Pfizer vaccine) released in late August showed that the third dose reduced the risk of testing positive for SARS CoV-2 by more than tenfold two weeks after injection. In another retrospective pre-print study, the researchers drew on health insurance data and calculated that the third dose of vaccine roughly halves the chance that a person will test positive from the first week after the injection and reduces it further after the second. In the first work, researchers from the Israeli Ministry of Health analyzed information on beyond 1.1 million Israelis over 60. They found that 12 days after the third dose the risk of infection was reduced by 10 times: this reports 95% protection already seen after the second dose. The effect against serious illness been even greater, e the risk was reduced by 15 times. However, the authors cautioned that the outcome was uncertain given the small number of patients who developed severe disease and the short time frame in which the study took place (July 30-August 22).
In the other study, the team analyzed the results of 182,076 swabs performed on people over 40 enrolled in Israeli health insurance performed in the first three weeks of August. Between 7 and 13 days after the recall a person’s chance of testing positive decreased by 48% compared to those who had received two doses; dat 14 to 21 days after the booster the probability decreased by 70%. This research did not look at serious illness but only new infections. Daniel Weinberger, of Yale University who contributed to the study, points out that short-term protection is only part of the puzzle and our work has limited numbers.
The importance of long-term data
David Dowdy, an epidemiologist at Johns Hopkins University, interviewed by the journal Science comments that it is not surprising to find that boosters can reduce infections: If the goal is to provide certain categories with high levels of immunity in the short term, there is no doubt that a good way to do it both with the recall. The results among other things tell us that current vaccines are still effective against the Delta variant. Since the studies only cover a short time after the recall, it is unclear how long the increase in protection will last. We need long-term data before we can say that booster is the right strategy. Efforts still need to focus on finding those who have not yet been vaccinated.
Side effects of the third dose
What will be the side effects of the booster? Is there a higher or lower risk of an adverse event than with previous injections? In reality, the data are still so limited that it is difficult to give a definitive answer. Overall, Covid-19 vaccines are extremely safe and extraordinarily effective. But when vaccinations reached millions of people around the world starting late last year, rare, sometimes serious, side effects emerged. They were so rare that clinical trials that led to vaccine authorization, even with tens of thousands of participants, failed to pinpoint them. From the analyzes made public so far we know that i boosters have safety features similar to previous doses. Since most vaccination-related problems occur shortly after inoculation, if there was a dramatic increase in the risk in terms of the safety profile we probably could have seen it already.
In particular we have seen that after the second dose of Pfizer or Moderna vaccines many people have experienced fever, headache, muscle aches, this is because the immune system was responding. If the first vaccine introduced the body to the spike protein, at the second dose the immune system responded with greater vigor and jumped to attention when it encountered the spike protein again, as seen recently, he comments. Kawsar Talaat, a Johns Hopkins infectious disease physician and vaccine researcher interviewed by Stat. To this he adds – some people may experience something similar after the third dose. Mark Slifka of Oregon Health and Science University, an expert in immunology, viruses and vaccines, argues that it all depends on how long it takes from the second to the third dose: If the booster is given eight months after the conclusion of the vaccination cycle, it is likely that the immune system will have calmed down and the new injection will not cause the effects most often seen after the second dose.
September 12, 2021 (change September 12, 2021 | 9:02 pm)