France and England have recommended second Covid vaccine booster to seniors, although early data from Israel shows protection against the Omicron variant substantially does not increase
1 – Who is entitled to the fourth dose of the anti-Covid vaccine in Italy today?
A Circular from the Ministry of Health of February 20 established the start of the administration of the fourth dose (with an mRna vaccine) for frail patients aged 12 years and over, 120 days after the third dose. The circular indicates the categories of patients admitted: subjects with marked impairment of the immune response, for causes related to the underlying disease or pharmacological treatments and subjects undergoing solid organ transplantation. The injections started on March 1st. To date, around 30,000 fragile people have received the so-called second booster (3.7% of the total).
2 – What do we know about the protection offered by vaccines?
According to several studies, the completion of the vaccination course (three doses) leads to the production of a very wide variety of antibodies, theoretically effective against any variant of the virus at least as regards severe disease. In addition, the memory immune cells (T lymphocytes), produced after immunization, create a response that protects (even against Omicron) for several months. We know that the antibody titre begins to drop four months after vaccination (third dose included) and this explains why even the vaccinated and the recovered can reinfect, usually in a mild form. As for the frail people described in the Ministry Circular, they are people who, having a compromised immune system, do not respond effectively to vaccines. The fourth dose was therefore recommended because, in the absence of contraindications, it may contribute to the achievement of a sufficient antibody titre to be protected from severe disease, as are healthy subjects after the third dose.
3 – Will the fourth dose be extended to the entire population in the future?
According to various experts, the decision on the fourth dose for all depends on the vaccination strategy that a country intends to pursue. If the goal is to keep the circulation of the virus low and avoid contagions, the further booster it can make sense. If, on the other hand, the aim is to prevent severe disease and death, the fourth generalized dose is probably not necessary, because with three doses the complete vaccination cycle (as happens with other types of vaccines) and avoids severe forms and hospitalization. It must be said that, according to preliminary studies conducted in Israel, where the administration of the fourth dose started a couple of months ago (to healthcare workers, over 60, frail patients, military), it seems that the protection against Omicron after the second booster remains substantially equal to that guaranteed by the third injection, ie it does not prevent the possibility of a mild infection although the level of neutralizing antibodies can increase up to five times.
4 – What happens in other countries?
In England, the administration of the fourth dose will be started to all over 75, immunosuppressed people and guests of retirement homes in the coming weeks, as stated by the Minister of Health Sajid Javid. For several months, Boris Johnson’s government has eliminated all anti-Covid restrictions. In France, Prime Minister Jean Castex has announced the launch of the campaign for the second booster, reserved for people aged 80 and over and who have received the third dose for over 3 months. The French government has also opted for an end to containment measures, including the obligation to wear a mask indoors and the super green pass. Fourth dose also launched in Denmark, United States, Hungary, Spain, Brazil and Turkey, with different modalities. In Germany, the independent vaccine panel, Stiko, has recommended the additional injection for people aged 70 and over and categories at risk.
5 – How is the pandemic evolving?
As noted by the Higher Institute of Health in the latest Report, we are witnessing an inversion of the trend of the epidemic curve, which starts to rise again. But the effectiveness of vaccines is confirmed: among the unvaccinated the mortality rate is 15 times higher than in those immunized even with the booster dose. The highest incidence of infections is occurring in the 0-19 year range. Reinfections with Omicron are over 3% of reported cases. Faced with this situation, for Guido Rasi, former executive director of the European Medicines Agency (Ema) and consultant to the emergency commissioner Figliuolo, the parameters to be monitored from now to June will first of all be the quantity of reinfections and who is reinfected. It is necessary to understand how much immunity will decline in these 3-4 months, if it will continue to decline or if reinfections will be marginal or in any case characterized by negligible symptoms – said Rasi to thetime.news Health -. We face various scenarios: we could see if a fourth dose protects us sufficiently from reinfection and if this is the only weapon. If the population that becomes ill with reinfection is relatively circumscribable – diabetics and vulnerable groups – perhaps it is worth intervening with the pharmacological tools that we now have: oral antivirals, specific monoclonal drugs and the upcoming preventive monoclonals. You can consider using all the arsenal before doing a mass vaccination, which however remains an option to keep open.
6 – Could so many vaccinations weaken the immune system?
As explained to the Courier service Mario Clerici, full professor of Immunology at the University of Milan and scientific director of the Don Gnocchi Foundation, a phenomenon that has been observed in experimental animals since the 1970s. If you expose an organism to high doses of a viral antigen (present in a vaccine, ed) in succession, a state of “tolerance” is created. In other words: certain immune cells (called beta) no longer produce antibodies: those that are measured in the blood and that are a first barrier to the virus. However, the so-called cellular response remains effective (that of T lymphocytes, ed).
March 13, 2022 (change March 13, 2022 | 17:48)
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