How well did the Pfizer-BioNTech vaccine work in adolescents?
The Pfizer-BioNTech vaccine was originally authorized for people 16 and older.
In a trial of nearly 2,300 adolescents between 12 and 15 years old, half received the two-shot regimen that was shown effective and safe in adults and half received a placebo. Researchers took blood samples after vaccination and measured antibody levels triggered by the shots. They found stronger immune responses in the teens than in young adults who had already been shown to be protected in the original trial. This is a common way of investigating whether a vaccine is effective in groups of people not included in the original trial, called “immune bridging.” There were 16 cases of covid-19 — the illness caused by the virus — in the trial, all of them among adolescents who received a placebo. That offered direct evidence that the shots provided strong protection against illness.
What were the side effects?
The most common side effects were similar to those seen in adults, including pain at the injection site, fatigue, headache, chills, muscle aches and fevers. The side effects tended to be somewhat more common in adolescents. For example, 63 percent of participants 16 and older reported fatigue, but 78 percent of those 12 to 15 years old did. About 14 percent of people 16 and over reported fevers, but 24 percent of younger adolescents did. Side effects were most common after the second dose. The vaccine has also caused very rare anaphylaxis reactions.
What about longer-term side effects?
Most vaccine side effects occur within two months of receiving the shots. That is why the FDA concentrated on this data when considering whether the vaccines were safe. The children in the trial will continue to be monitored for two years. However, very rare side effects are often not picked up within clinical trials. Longer-term monitoring of the safety of the vaccine will continue to track adverse events, severe cases of covid-19 that cause hospitalization or death, and cases of a serious and rare inflammatory syndrome.
When will the Pfizer vaccine be available to this age group?
Some states, such as Arkansas, Delaware and Georgia, opened eligibility to teens 12 and older for the shots Tuesday. Many other states were waiting for action from the Centers for Disease Control and Prevention. An expert advisory panel to the CDC voted Wednesday to recommend the vaccine be used among 12- to 15-year-olds. The recommendation of the Advisory Committee on Immunization Practices is expected to be approved by CDC director Rochelle Walensky within hours. Once that happens, the inoculation can be given anywhere authorized to administer the shots.
Will the vaccine be required for school entry?
It will be up to state governments to decide which vaccines are required for school entry in their jurisdictions. But Dorit Reiss, a law professor focused on vaccine policy at the University of California Hastings College of Law, said she does not think a coronavirus shot would be mandated in schools without the vaccine receiving full regulatory approval.
Can the coronavirus vaccine be given along with other childhood or adolescent immunizations?
There is no data on how the vaccines interact with other immunizations. After a discussion of the issue Wednesday, the CDC advisory panel agreed that the coronavirus vaccine could be given at the same time as other vaccines. The American Academy of Pediatrics was expected to issue a policy statement Wednesday supporting the administration of the coronavirus vaccine with other childhood or adolescent inoculations — such as vaccines targeting human papillomavirus, known as HPV, or meningococcal disease. There are few vaccines that pose a problem when administered with other shots.
Are other vaccine-makers testing their vaccines in this age group?
Moderna announced in May that an initial analysis of its teen trial found its vaccine was 96 percent effective among participants who received at least one dose. Moderna is in discussions with regulators about the data.
What about coronavirus vaccines for younger children?
Pfizer-BioNTech and Moderna are testing their vaccines in children as young as infants. Trials in younger children are expected to take longer, because researchers must step down gradually in age and determine a safe and effective dose.
First, researchers must establish a safe and effective dose, which may be lower than the dose in adults or teens. They will do this by testing different doses, first in older children, for example 5- to 11-year-olds, before moving down to 2- to 4-year-olds and then children as young as 6 months. Then, they will test whether the vaccines are safe or effective, by measuring whether they trigger equivalent immune responses in children’s blood. Pfizer expects to have data on children as young as 2 years old by September or October, with data from younger children expected by the end of the year.
How will regulators scrutinize the vaccines for younger children?
As a start, the FDA said it will convene a meeting of its outside vaccine experts June 10 to discuss the data needed to authorize pediatric vaccines, focusing on children younger than 12. “We recognize that the next critical step is having vaccines available for use throughout the pediatric population,” Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said in a statement.
“As we get down to younger children age 11 and below, different doses of the vaccine will need to be used,” he said in a news briefing Monday. “There are also different risk-benefit considerations because we know that younger children have been susceptible to this interesting multi-inflammatory syndrome with covid-19, and we have to make sure we’re not going to see anything untoward in the youngest children.”