Moderna’s COVID-19 Vaccine Is Safe and Effective in Adolescents

Moderna has announced that a Phase II/III clinical trial, known as TeenCOVE, of its COVID-19 vaccine (mRNA-1273) in adolescents has met its primary immunogenicity endpoint. The public statement is not accompanied by data at this stage, but the biotechnology company said that it plans to submit the findings to a peer-reviewed journal for publication.

COVID-19 vaccines for kids

mRNA-1273 was granted Emergency Use Authorization (EUA) by the US Food and Drug Administration (FDA) on December 18, 2020 for individuals aged 18 years and over. Over the last five months, alongside other authorized COVID-19 vaccines, it has been distributed to various locations worldwide and administered to the most vulnerable populations; namely the elderly and those with underlying health conditions.

So, when should young, generally healthy individuals expect to be immunized against COVID-19? The vaccine clinical trials conducted in 2020 did not include any individuals below the age of 18 years.

This is common procedure when developing a novel drug or vaccine; they are initially trialled in higher age brackets. Once the safety and efficacy is demonstrated in adults, the testing process moves down to lower age brackets, such as adolescents.

The TeenCOVE study recruited 3,732 adults aged between 12–18 years. Participants were randomized to either receive two 100 µg doses of the Moderna vaccine or a placebo. The primary endpoint of the study was non-inferior immunogenicity compared to the previous Phase III study adult comparator group.

Vaccine efficacy of 93% in adolescents

According to the statement from Moderna, zero cases of COVID-19 were reported in participants that received two doses of the COVID-19 vaccine. An overall vaccine efficacy of 93% was determined in people that were seronegative – meaning that they did not possess antibodies against SARS-CoV-2, which implies they have not been infected by the virus previously.

“We are encouraged that mRNA-1273 was highly effective at preventing COVID-19 in adolescents. It is particularly exciting to see that the Moderna COVID-19 vaccine can prevent SARS-CoV-2 infection,” Stéphane Bancel, chief executive officer of Moderna, said. “We will submit these results to the US FDA and regulators globally in early June and request authorization. We remain committed to doing our part to help end the COVID-19 pandemic.”

The company states that, in the TeenCOVE study, the vaccine was "generally well tolerated" with a safety profile that was consistent with the Phase III COVE trial in adults; the most common side effect being pain at the site of injection.

Is an EUA for vaccine use in adolescents next for Moderna?

TeenCOVE is the second clinical trial that has explored the safety and efficacy of mRNA-based COVID-19 vaccines in younger populations. Earlier in March, Pfizer–BioNTech announced that in a study of BNT162b2 in 12–15-year-olds, vaccine efficacy was calculated at 100%.

Speaking of the latest results shared by Moderna, Russell Viner, professor of adolescent health at the University College London Institute of Child Health in London, said, "These data, added to data on a similar number in the Pfizer trial […] show that mRNA vaccines are as immunogenic and effective in teenagers as they are in adults. We need to see the actual data to confirm this however this is both encouraging and expected."

Pfizer shared the adolescent trial data to the FDA, and subsequently the company received an EUA for BNT162b2 to be made available for adolescents 12 through 15 years of age. Viner suspects that the positive results reported by Moderna may result in a similar outcome for mRNA-1273.

Moderna concludes its statement by confirming that safety data continues to be accrued, and the participants of TeenCOVE will be monitored for 12 months after their second injection to evaluate long-term protection and safety.