Pfizer vaccine much less successful at preventing Covid infections in young children, data shows

‘In the Omicron era, the effectiveness against cases of BNT162b2 declined rapidly for children, particularly those 5-11 years,’ a new study says

Pfizer’s Covid vaccine is far less successful at blocking infections in young children than in adults and adolescents, a new study shows.

According to a set of New York state data published on medRxiv, the vaccine provided almost no protection against contracting the coronavirus for children aged five to 11, even within a month of receiving their second shot. The vaccine was effective, however, at preventing severe illness and hospitalisation in that age group.

“In the Omicron era, the effectiveness against cases of BNT162b2 declined rapidly for children, particularly those 5-11 years,” the study says. “However, vaccination of children 5-11 years was protective against severe disease and is recommended.”

Experts say the drop-off may be due to the lower dose used for children, which is one third the amount administered to teenagers and adults. While those aged 12 and older receive 30 micrograms with each shot, 5-11-year-olds only get 10.

In its conclusions, the study suggested reevaluating those doses.

“These results highlight the potential need to study alternative vaccine dosing for children and the continued importance [of] layered protections, including mask wearing, to prevent infection and transmission,” the authors said.

The data used in the study was gathered in December 2021 and January 2022, during the peak of New York’s wave of Omicron cases. Experts say that may also have contributed to the reduced effectiveness, since Omicron is a significantly different and more contagious version of the virus than what the Pfizer vaccine was designed for.

Registered nurse administers the Pfizer Covid-19 vaccine at Sydney Road Family Medical Practice in Balgowlah on 11 January 2022 in Sydney, Australia (Getty Images)

“It’s disappointing, but not entirely surprising, given this is a vaccine developed in response to an earlier variant,” Dr Eli Rosenberg, who led the study, told The New York Times. “It looks very distressing to see this rapid decline, but it’s again all against Omicron.”

In the United States, Pfizer’s vaccine is currently the only one authorized for children in the 5-11 age group, or even for those aged 12-17.

The Independent has reached out to Pfizer for comment.