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Moderna said its COVID-19 vaccine was 100% effective for teenagers in clinical trials, and the company plans to seek emergency use authorization (EUA) from the Food and Drug Administration (FDA) in early June.
The data came Tuesday just as the Centers for Disease Control and Prevention (CDC) released information on breakthrough infections among vaccinated people of all ages.
Moderna’s trials enrolled more than 3,700 adolescents ages 12-17 years who were randomized to receive the vaccine or a placebo. After two doses, there were four cases of COVID-19 in the placebo group and none in the vaccine group, according to a Moderna press release. The data have not been published in a peer-reviewed journal.
The company also analyzed data based on a COVID-19 case definition that includes more mild disease and found a vaccine efficacy of 93% after the first dose. In addition, an immunogenicity analysis showed teens’ immune responses were just as robust as those of adults.
The teen trials did not present any significant safety concerns, according to Moderna. The most common side effects from the vaccine were injection site pain, headache, fatigue, myalgia and chills.
Moderna’s results come two weeks after the FDA extended an EUA for the Pfizer-BioNTech vaccine for adolescents as young as 12. Trials for that vaccine also showed 100% efficacy for adolescents.
More than 4.7 million adolescents ages 12-17 have received at least one dose of COVID-19 vaccine, according to CDC data. While the vaccines have been safe and effective, the CDC is investigating a small number of cases of myocarditis in adolescents and young adults after vaccination to see if they are related. Most of those cases have been mild, but pediatricians should report any such cases to the Vaccine Adverse Event Reporting System.
Breakthrough COVID-19 infections
The CDC on Tuesday released an analysis of breakthrough COVID-19 infections as of April 30 among the 101 million people in the U.S. who were fully vaccinated. The data show 10,262 such infections in 46 states and territories, although authors acknowledge this is likely a “substantial undercount” because many breakthrough infections are asymptomatic or mild.
About 63% of the breakthrough cases were in females, and the median age was 58 years, according to a new Morbidity and Mortality Weekly Report. About 27% people were asymptomatic, 10% were hospitalized and 2% died. Among the 160 patients who died, the median age was 82 years and 18% were asymptomatic or died of an unrelated cause.
Sequencing data from 555 breakthrough cases found 64% were attributed to a variant of concern, most commonly B.1.1.7.
“Even though FDA-authorized vaccines are highly effective, breakthrough cases are expected, especially before population immunity reaches sufficient levels to further decrease transmission,” CDC authors said in the report. “However, vaccine breakthrough infections occur in only a small fraction of all vaccinated persons and account for a small percentage of all COVID-19 cases. The number of COVID-19 cases, hospitalizations, and deaths that will be prevented among vaccinated persons will far exceed the number of vaccine breakthrough cases.”
As of May 1, the CDC is only investigating breakthrough infections in which a patient is hospitalized or dies.