Pfizer has initiated the first clinical trials of its COVID-19 vaccine for children under 12. The inaugural participants—two nine-year-old twin girls—received their doses on Wednesday at Duke University in North Carolina.
Over recent weeks, leading pharmaceutical companies have expanded COVID-19 vaccine trials to younger age groups. For instance, Moderna is now evaluating its vaccine in U.S. children aged six months to 12 years, building on successful tests in those over 12, with results anticipated soon.
AstraZeneca commenced trials in children six months and older last month. Johnson & Johnson plans to extend testing to younger children following evaluations in those over 12.
Pfizer is now focusing on pediatric populations, testing three doses (10, 20, and 30 micrograms) in 144 participants. Doses will first be assessed in children aged 5 to 11, then 2 to 4, and finally 6 months to 2 years.
Once the optimal dose is identified, Pfizer will enroll another 4,500 children. Two-thirds will receive two doses of the vaccine 21 days apart; the remainder will get placebo saline injections. Immune responses will be measured via blood samples taken seven days post-second dose.
Given children's potentially stronger reactions to vaccines compared to adults, side effects will be closely monitored.
Trial results are expected in the second half of the year. Pfizer spokesperson Sharon Castillo stated the company aims to authorize vaccination for young children by early 2022.
In the U.S., over 3.3 million children (13% of total cases) have tested positive for COVID-19, with at least 13,000 hospitalizations and 260 deaths, per American Academy of Pediatrics representative Dr. Yvonne Maldonado.
Achieving herd immunity may require vaccinating 80% of the population, yet children under 18 comprise about 23% of Americans.
Even with high adult vaccination rates, "herd immunity will be challenging without vaccinating children," notes Dr. Emily Erbelding, infectious disease specialist at the National Institutes of Health overseeing U.S. pediatric COVID-19 vaccine trials. She adds, "this effort will enable school reopenings and help end the pandemic."
