Moderna’s COVID-19 vaccine has hit the primary endpoint in a Phase II/III study in adolescents, with no cases of the disease observed in participants who had received two doses of the jab.

The TeenCOVE study enrolled more than 3,7000 participants aged 12 years to less than 18 years in the US.

According to Moderna, the study met its primary endpoint of non-inferior immunogenicity versus the Phase III study adults comparator group.

Within the study, a vaccine efficacy of 93% in seronegative participants was observed, starting 14 days after the first doses using the secondary CDC case definition of COVID-19, which requires only one symptom of the disease and nasopharyngeal (NP) swab or saliva sample positive for SARS-CoV-2.

In addition, the vaccine – known as mRNA-1273 – was generally well tolerated, with no significant safety concerns identified to date.

Most adverse events were mild-to-moderate, with the most common adverse events being injection site pain, headache, fatigue, myalgia and chills.

“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,” said Stéphane Bancel, chief executive officer of Moderna.

“We will submit these results to the US Food and Drug Administration [FDA] and regulators globally in early June and request authorisation. We remain committed to doing our part to help end the COVID-19 pandemic.”

Moderna added that all participants in the TeenCOVE study will be monitored for 12 months after their second dose to assess long-term protection and safety.

The company is also planning to submit data from this study to a peer-reviewed publication.