Moderna says its Covid-19 vaccine found safe, effective in teens

Moderna’s Covid-19 vaccine was shown to be effective in adolescents aged 12-17.
Moderna’s Covid-19 vaccine was shown to be effective in adolescents aged 12-17.PHOTO: REUTERS

CHICAGO (REUTERS) - Moderna's Covid-19 vaccine was shown to be effective in adolescents aged 12 to 17 and showed no new or major safety problems in a clinical trial, the developer said on Tuesday (May 25), potentially setting the stage for a second vaccine for school-aged children to be authorised in July.

Moderna, whose vaccine is authorised for adults aged 18 and older, said it will submit the findings of its adolescent study to the United States Food and Drug Administration and other regulators for emergency use authorisation in early June.

US regulators took about a month to review a similar study from Pfizer/BioNtech, which was authorised for ages 12 to 15 on May 10. If Moderna gets the same treatment, its authorisation would come in early July.

Most children with Covid-19 develop only mild symptoms or no symptoms. Yet children remain at risk of becoming seriously ill and can spread the virus. Widely vaccinating 12- to 18-year-olds could allow US schools and summer camps to relax masking and social distancing measures suggested by the US Centres for Disease Control and Prevention (CDC).

"We are encouraged that mRNA-1273 was highly effective at preventing Covid-19 in adolescents," said Moderna's chief executive Stephane Bancel in a statement.

Moderna's trial evaluated the vaccine in 3,732 adolescents aged 12 to 17, two-thirds of whom got the vaccine and one-third of whom got a placebo. The main goal was to produce an immune response on par with that seen in the company's large, phase three trial in adults, which was 94.1 per cent effective at preventing Covid-19.

Two weeks after the second dose, researchers found no cases of Covid-19 in the vaccine group compared with four cases in the placebo group, resulting in a vaccine efficacy of 100 per cent, based on case definitions from the company's adult trial.

Using a case definition from the CDC, which requires only one Covid-19 symptom, the vaccine was found to be 93 per cent effective, suggesting the vaccine may be protective against cases with milder symptoms, said the company.

The researchers found no new safety issues. The most common side effects after the second dose were headache, fatigue, body aches and chills.

The company said it is still accumulating safety data. All study participants will be monitored for 12 months after their second dose to determine long-term protection and safety.

Moderna said it plans to submit the data to a peer-reviewed publication. The company is currently testing its vaccine in children as young as six months of age.

In addition to the US, Pfizer's vaccine is also authorised for use in younger teens aged 12 to 15 in Canada and Algeria.