Vaccinations for babies, toddlers and preschoolers began in the US in June after months of delays. Only about 6 percent of youngsters ages 6 months to 4 years had received at least one dose of the COVID-19 vaccine by mid-August, according to the American Academy of Pediatrics.
Health authorities have approved small doses of vaccines made by Pfizer and its partner BioNTech based on research showing they are safe and produce high levels of antibodies that fight the virus. But there was only preliminary data on how that translated into effectiveness vs symptomatic COVID-19.
There were 21 cases of COVID-19 among the 351 children who received the sham vaccines—compared to just 13 among the 794 youngsters who received three doses of the vaccine.
The cases in children were mainly caused by the BA.2 Omicron version that was circulating at the time. Today, another relative of Omicron, BA.5, causes most cases of COVID-19 in the US and much of the world.
In older children and adults, Covid-19 vaccines have been used long enough to show that they remain strong defenses against severe disease and death even as the coronavirus mutates – while early defenses against infection weaken. Still, scientists are tracking this initial effectiveness rate as further evidence of the vaccine’s effectiveness — and to look for signs of how it initially holds up against new mutants.
Pfizer this week asked US regulators to allow modified vaccine doses that better match the latest Omicron variants for people 12 and older as boosters this fall. The company said it is also developing updated photos for children under 12.
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