A corporate announcement Thursday that a small clinical trial showed a booster shot of the Pfizer-BioNTech coronavirus vaccine boosted the immune response of 140 children aged 5 to 11 comes as new cases of the virus in the United States are on the rise again.
The upturn was particularly noticeable in the Northeast, where the Omicron subvariant known as BA.2, now the dominant version of the virus in the United States, first took hold.
Dr. Anthony S. Fauci, President Biden’s chief medical adviser, has warned in recent days that the United States could see a significant increase in infections in the coming weeks. But he said hospitalization rates are unlikely to rise in tandem because so many Americans have some degree of immunity, either from vaccines or previous infections.
Several hundred children aged 5 to 11 have died from Covid since the pandemic began, according to the Centers for Disease Control and Prevention, but pediatric injections have been a tough sell for many parents. Only about 28% of children in this age group received two doses and would be eligible for a booster. About 7% received only one dose, according to agency data.
There was an initial rush for vaccines after they were first offered for this age group in November, but the increase in vaccination rates then slowed. Over the past month, for example, it has increased by a single percentage point.
Dr. Kathryn M. Edwards, a pediatric vaccine expert at Vanderbilt University School of Medicine, said some parents believe the chances of their children becoming seriously ill are low, when vaccines are unknown. She said some research indicates that 45% of infected children show no symptoms.
“The problem is that we can’t predict who will get sick and who won’t,” she said. And among those who do, she said, “there will be children who are going to be hospitalized, and there will be some deaths.”
Dr. Sally Goza, a pediatrician from Fayetteville, Georgia and former president of the American Academy of Pediatrics, said some parents see no reason to act because they consider the pandemic to be under control. “I’ve had parents come into my office and say, ‘Covid, it’s over. I don’t need to worry about that,” she said.
To some extent, she said, parents have also been numbed by wave after wave of infection. “People are tired of dealing with it. They’re just like, ‘We’re just going to take a chance,'” she said.
According to a study by the Kaiser Family Foundation, the proportion of children aged 5 to 11 receiving at least one dose varies considerably from region to region. Five of the 10 states with the highest rates were in New England, while eight of the 10 states with the lowest rates were in the South.
Even though more than 250 million Americans have been safely vaccinated since the start of the pandemic, pediatric experts say many parents fear unknown consequences for their children. Compared to injections to protect against measles, mumps and other diseases, which have been around for decades, Covid vaccines are brand new.
A study by New York researchers, published online in late February, found that for children aged 5 to 11, the effectiveness of the Pfizer vaccine against infection fell to 12% from 68% in the 28 34 days after the second dose.
This was a steeper drop than for older teens and teens who received a much higher dose. Some experts have suggested that the difference in dosage explains the protective gap, while others have blamed the Omicron variant that was prevalent during the study.
Another CDC study said two doses of Pfizer reduced the risk of Omicron infection by 31% in 5- to 11-year-olds, compared with a 59% reduction in risk in 12- to 15-year-olds.
The Pfizer vaccine is currently the only one authorized for children under 18.