What emerges from a new study on the recall times of the Pfizer vaccine
Preliminary UK research has observed an enhancement of the immune response but currently does not recommend postponing it as the delta variant is only covered by 2 doses
(photo: Soumyabrata Roy / NurPhoto via Getty Images) receiving both doses of vaccines, therefore completing immunization, is an essential weapon against Covid-19 and even more important to protect against the more contagious delta variant. But how long should or can elapse between the first and second dose? A new English study, in which the University of Birmingham took part, shows that, in the case of Pfizer-BioNTech's mRna vaccine, even if it were decided to postpone the booster, doing it up to 14 weeks later, the immune response it could be equally substantial.The results, not yet peer reviewed, are available in a preprinted text. However, the research does not indicate in any way to postpone the second dose, which indeed, as recently confirmed by an extensive work in the New England Journal of Medicine, is essential (and within the indicated times), especially to defend against the delta variant. While for those who have had Covid-19 and are cured, a new simplification could soon arrive, at least in Italy, with the possibility of being vaccinated up to 12 months after infection and receiving only one dose. And that's not all: today the emergency use authorization for the Moderna vaccine arrives from the European Medicines Agency (EMA) even from 12 to 17 years old, while the Pfizer-BioNTech vaccine is already administered in Italy also in that age group.
Recall: 6 to 14 weeks later?
Pfizer-BioNTech and Moderna mRna vaccines require a booster at a distance of 3 or 4 weeks, respectively, with a tolerability margin , recognized by the authorities, up to 42 days. More than one research is analyzing whether a further postponement of the second dose could represent a good strategy, with a view to covering a larger share of the population with a first dose and then reaching everyone. Research by the Birmingham and Oxford group (as well as other UK agencies) compared the immune response of 503 healthcare workers vaccinated with the Pfizer-BioNTech vaccine at different timelines. 44% of the participants had previously contracted Covid-19. One group of volunteers received the second dose at standard times (3 to 5 weeks after the first dose) while another group was given it over 6 to 14 weeks after.What happens between the first and second dose
Although the research includes only about 500 people and is not yet officially published, the preliminary data provide a first indication that a prolonged interval between the two doses could lead to some advantages. On the one hand, the clinical trial underlines that in the long term between the vaccine and the booster the level of specific antibodies against Sars-Cov-2 drops significantly and more than what happens with the traditional vaccination plan. Also for this reason, for now, there is no advice to postpone vaccination, especially now that the delta variant is more widespread and we know that it is little covered by a single dose. However, there is good news: in all weeks of the interval the concentration of T lymphocytes (or T cells) - at the basis of cellular immunity, an important part of total immunity - remains high.What happens after the second postponed dose
In the postponed plan, moreover, from the analyzes carried out after the second dose it emerges that the antibodies rise considerably and are even more present - up to double - than those produced after the recall carried out according to the standard calendar. Furthermore, the researchers point out that with a longer interval the immune response linked to antibodies is also wide against the delta and other variants "of concern" (according to the WHO classification). T cells, on the other hand, are 1.6 times lower than in the traditional plan, although a particular subgroup of these, called T helper cells, are important for long-term immune memory and help stimulate the production of antibodies.When and with how many doses should the recovered be vaccinated
The case of those who have already had Covid-19 and are cured is slightly different. Currently in Italy the guidelines provide that the recovered receive a first dose of vaccine a little distant from the infection, at least after 3 months but no later than 6 months. Currently new evidence and research published in Nature Communications indicate that protection for those who have had Covid-19, both symptomatic and symptomatic, could last longer, at least 9 months. It is no coincidence that the Undersecretary of Health Andrea Costa told the Ansa agency that the government is considering further postponing the vaccination for the recovered, probably within 12 months, and with a single dose (and not two) - a ' indication that it was already present (not in the form of an obligation) in a circular of March 2021 from the ministry.Web - 13 hours ago
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Topics
Coronavirus Vaccine coronavirus Modern vaccine Pfizer BioNTech vaccine globalData.fldTopic = "Coronavirus, Vaccine coronavirus, Modern Vaccine, Pfizer BioNTech Vaccine "
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