COVID-19: Vaccines for children will be more effective

A year ago, the issue of vaccinating children against Covid-19 was controversial due to the low risk of developing severe forms of the disease. And even if it was The benefits far outweigh the risksExperts agreed that the ideal is to get the epidemic under control so you don’t have to ask that question. “If the epidemic is brought under control and there are very few cases, this may not be necessary‘, Chairman of the Vaccine Strategy Steering Board Alan Fisher expressed during a Interview on the topic in August 2021. To reduce the risk of adverse effects as much as possible, a reduced version of the Pfizer vaccine has been validated, containing a dose three times lower than that used for adolescents and adults (10 mcg versus 30 mcg). Despite this low dose, the vaccination of children has Proven to be highly protectivewhile being severe Safe. However, the vaccine in children generates fewer antibodies than in adults. But these appear to be more effective, according to a new study.

Less antibodies, but better quality

The study was published online as Prepress (not yet reviewed) on May 21, 2022 by the American Ragon Institute, a group of researchers from Massachusetts General Hospital, MIT, and Harvard University. They compared the immune response after vaccination of children aged 5 to 11 years at this reduced dose with that of adolescents and adults receiving a normal dose of 30 mcg. To do this, they collected blood samples from 32 children, 30 adolescents (12-15 years old), and 9 adults (over 16 years old), before each dose and 2 to 4 weeks after the second dose.

First observation: children produced less antibodies to the coronavirus than adolescents or adults. But it’s possible that this is not due to a lower dose, because teens also have a lower amount of antibodies than adults.

However, these antibodies remained highly effective in driving the virus against immune cells capable of destroying it. This mechanism is mediated by Fc receptors, on the surface of lymphocytes and macrophages, among other immune cells. The antibody picks up the virus and also binds to these receptors, allowing these cells to deal with the intruder. Identification of Fc receptors was higher in adolescents and similar in children and adults, despite the lower number of antibodies, indicating better efficacy of these antibodies.

The second dose is necessary for optimal defense

This ability to activate immune cells was activated from the first dose for all three age groups, but it increased after the second more in children than in adolescents, while it increased very little in adults. Thanks to this increased effect after the second dose, children had similar or higher activity than adults for many immune cells, including neutrophils, monocytes, and natural killer lymphocytes (for natural killer or natural killers).

Antibodies from children recognized variants (Alpha, Beta, Gamma, Delta, and Omicron) in addition to those from adults, although the quantity was lower. Even better, pediatric and adolescent M immunoglobulins recognized all variants better than those of adults (except for Omicron). These antibodies are the first to intervene during infection and activate innate immunity more than other antibodies. So it can lead to a better response against variants when the acquired immunity is not able to neutralize them. “This data points to a unique ability for young people that may enable them to recognize variants on a larger scale after vaccination”, explain the authors. For these reasons, the pediatric vaccine is highly effective against current variants of the coronavirus and should also protect them from new variants.

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