Pfizer Vaccine Less Effective at Stopping Infection in Kids 5 to 11, New York Study Says

The study found that between the two groups of children approved for the vaccine, infection was more likely in the younger; the data has not been peer reviewed

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A new study of vaccine effectiveness in young children, authored by health officials in New York state, suggests the Pfizer-BioNTech vaccine offered little protection against COVID-19 infection one month after full vaccination.

The Pfizer vaccine, the only shot with emergency approval for children ages 5 to 11, is less effective at preventing infection in that age group that in older teens and adults, the study found. Both age groups (5-11 and 12-17) saw a decline in protect against the virus, but the younger ones experienced a rapid decline "with low protection by one month following full-vaccination."

Data collected during December and January, in the height of omicron's surge, suggests vaccination still prevents the youngest ages from severe illness.

"In the Omicron era, the effectiveness against cases of [Pfizer-BioNTech vaccine] declined rapidly for children, particularly those 5-11 years. However, vaccination of children 5-11 years was protective against severe disease and is recommended," the authors of the study wrote.

Their research, not yet peer reviewed, analyzed data between those winter months in fully vaccinated children. In New York, 852,384 kids between 12 and 17 were fully vaccinated, and 365,502 between 5 and 11 received both doses.

In a review of their findings, researchers said the older group of children experience a decrease in vaccine effectiveness from 66% to 51%. The youngest group, which receives roughly one-third the dose of the vaccine as the older age groups, saw effectiveness drop from 68% down to just 12%.

Children age 12 had some of the highest vaccine effectiveness, a data point researchers believe could be due to "being small size relative to dose and more recent vaccination (by 6 weeks on average)than those 13-17 years."

“It’s disappointing, but not entirely surprising, given this is a vaccine developed in response to an earlier variant,” Eli Rosenberg, deputy director for science at the New York State Department of Health, told The New York Times. “It looks very distressing to see this rapid decline, but it’s again all against Omicron.”

What is clear, they stipulate, is the need for additional research the number of doses, amount of vaccine in each shot and timing between doses to better understand the division between age groups.

"These results highlight the potential need to study alternative vaccine dosing for children and the continued importance layered protections, including mask wearing, to prevent infection and transmission," the authors add.

The study, published Monday, comes just days after the CDC issued updated mask guidance, recommending the majority of Americans need not wear masks indoor unless at severe risk for illness. Two days later, Gov. Kathy Hochul announced the statewide mask order for schools would lift within the week.

Copyright NBC New York
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