Teenage COVID-19 Vaccine Recipients at Risk of Serious Adverse Events After 2nd Dose: Study

Researchers said more studies on adolescents and COVID-19 vaccination should be done to explore events among that population.

High school students receive Pfizer-BioNTech COVID-19 vaccines in Oslo on Sept. 7, 2021. Heiko Junge/NTB/AFP via Getty Images

Teenage recipients of COVID-19 vaccines faced an elevated risk of serious adverse events, including appendicitis, after a second dose, researchers said in a new study.

Norwegian scientists observed about 496,432 adolescents aged 12 to 19 for the study, published in Scientific Reports on March 27, utilizing nationwide safety data. Many of the adolescents received a messenger ribonucleic acid (mRNA) COVID-19 vaccine from Pfizer-BioNTech or Moderna.

Following a first dose, there were no significant increases in adverse events, the scientists said. An age-adjusted analysis identified an increased incidence of appendicitis and allergic reactions, but the small number of events means those increases should be “interpreted cautiously,” they wrote.

In contrast, after the second dose, there was a higher incidence of allergic reactions, swollen lymph nodes, and heart inflammation. When isolating people without reported COVID-19 infections, an elevated risk of epilepsy and convulsions also appeared.

Stratifications by age showed that the heart inflammation cases were primarily among 18- to 19-year-olds, who have been known to face an increased risk of the inflammation—for which doctors often advise refraining from physical activity for a period of time—following COVID-19 vaccination. The older adolescents also had an increased risk of allergic reactions, while 16- to 17-year-olds had more events of acute appendicitis, which typically requires surgery.

The Norwegian researchers restricted their primary analysis to events occurring within two to 42 days after vaccination, depending on the type of event. They acknowledged that the risk windows may be too brief, as estimates of risk increased for certain events after the elapsed time.

The research was funded by the Norwegian Institute of Public Health. Several authors reported receiving funding from pharmaceutical companies, such as GlaxoSmithKline. Neither Pfizer nor Moderna was listed as paying any of the scientists.

German Tapia, a researcher with the Norwegian Institute of Public Health, and coauthors said that the study found that “the number of observed outcomes and statistically significant associations were generally low, with some exceptions.” They called for more studies on adolescents to explore age-specific adverse events, particularly for new mRNA vaccines.

Pfizer and Moderna did not respond to requests for comment.

The Vaccine Safety Research Foundation, based in the United States, said in a March 30 post on X that the study showed that “a clear ‘dose-dependent’ safety signal exists for cardiac inflammation in teens” and said authorities should withdraw the vaccines from the market.

A nurse prepares to give a COVID-19 vaccine to a boy in Denver on Nov. 3, 2021. Michael Ciaglo/Getty Images

The U.S. Centers for Disease Control and Prevention shifted from broadly recommending COVID-19 vaccination to advising patients to consult a health care professional before deciding, but a federal judge blocked that change in mid-March.

Jeffrey Morris, a professor of public health at the University of Pennsylvania who was not involved with the new study, said in response to the foundation that he believed the study “basically affirms what the other papers have already showed” and that the benefits of the vaccines outweigh the risks.