Pfizer’s low-dose Covid-19 vaccine failed in children under 5 years of age, study data show

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Today, he brought discouraging news for parents in the United States who hope to vaccinate their young children against Covid-19 soon. Based on clinical trial data, Pfizer and BioNTech announced On Friday that children aged 2 to under 5 did not produce a sufficient immune response to two injections of their low-dose covid-19 vaccine, even though they appeared to be children between 6 months and 2 years old.

The companies now plan to expand their research by adding a third low dose to the schedule, both for this age group and for children aged 5 to 12. And now it is expected that every vaccine approval for the age of six months to 5 years will have to wait until the first half of next year.

The Pfizer / BioNTech study collectively included more than 4,500 children aged six months to 11 years in the United States, Finland, Poland and Spain. Those older than 5 years received 10 micrograms of vaccine (one third of the adult dose) in a schedule with two doses 21 days apart, while those younger than 5 received a dose of 3 micrograms per injection.

In late October, the FDA authorized Pfizer / BioNTech vaccine for children aged 5 to 11 years. The decision is based on data showing that the vaccine was about 90% effective in preventing coronavirus disease, as well as data showing that their immune response is similar to that seen in younger adults. Unfortunately, that immune response was not as strong for vaccinated children in the 2 to 4 age group, Pfizer / BioNTech reported on Friday, based on a temporary analysis of the data.

Failure will inevitably delay any vaccination program for these age groups. Although children aged six months to 2 years seemed to have a solid immune response, the companies decided (with the blessing of regulators) to modify the study for all children under 5 years of age. He will now receive a third dose of 3 micrograms at least two months after the second dose. The companies also announced plans to study a third dose of 10 micrograms in children ages 5 to 11, as well as teens ages 12 to 17. If the third dose is then made effective for younger children, companies plan to apply for an Emergency Authorization (EUA) in the first half of 2022.

The decision to use lower doses for children was based on the hope that it would provide similar protection as injections for adults, while reducing all potential side effects, especially the increased but rare risk of heart inflammation (myocarditis) seen in teenagers. and young adults, more in men than in women. So far, at least, there it is not The CDC identified eight cases of myocarditis in this age group after vaccination, although it did not state whether these cases were related to vaccines. All cases seemed to be mild and at least five had already recovered, According to the CDC.

But the latest findings show that it can be difficult to balance the optimal dose and schedule for the vaccine, for all age groups. In light of research showing that immunity has begun to weaken in those vaccinated with two doses, as well as the emergence of variants like Delta and now Omicron, many scientists and even health officials have started to call for mRNA vaccines to be classified as three-dose, not two-dose vaccines. And that seems to be the direction Pfizer / BioNTech is heading.

In a conference call Friday, the New York Times reported Kathrin Jansen, head of Pfizer’s vaccine research department, has made it clear that the company will seek to approve its vaccines as a three-dose series for children. And if that happens, it could pave the way for the same to apply to all age groups.

Numerous studies have shown that people who have received three doses appear to have stronger protection against Delta infection and probably Omicron, although there is still the question of how long this boost in immunity will last.

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Naveen Kumar

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