Pfizer, Moderna expand sizes of vaccine trials involving children 5 to 11 years old

Photo (c) Roberto Jimenez Mejias - Getty Images

Health officials want more data on rare heart side effects in kids following vaccination

Pfizer and Moderna have reportedly increased the number of children enrolled in their vaccine trials in an effort to get more data on the rare heart-related side effects that children 5 to 11 years old have experienced after getting vaccinated. 

Citing sources familiar with the matter, the New York Times reported that the companies doubled the size of their studies at the prompting of the U.S. Food and Drug Administration (FDA). The agency asked the drugmakers to conduct a study involving 3,000 children in order to detect rare heart issues such as myocarditis or pericarditis. 

At the end of June, the FDA updated its vaccine fact sheet to state that there was a possible increased risk of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the tissue surrounding the heart) following vaccination. However, the CDC said these heart effects are very rare. Data suggests that they show up in just 12.6 cases per 1 million second doses. 

Preparing for the school year

Pfizer has already gotten its vaccine authorized for children 12 and older, and Moderna has gotten its vaccine authorized for those 18 and older. The expansion of the companies’ trials comes as schools prepare to reopen and as officials review data in order to determine what to recommend based on vaccination rates and the rapid spread of the Delta variant. 

Pfizer said on its website that it expects to have study results from its vaccine trials in children 11 and younger in September or October. Moderna told the New York Times that it expects to seek emergency authorization for its vaccine for use in kids younger than 12 in late 2021 or early 2022. 

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