Moderna’s mRNA COVID-19 Vaccine 100% Effective in Adolescents

May 25, 2021 - Moderna recently announced that the Phase 2/3 study of its COVID-19 vaccine in adolescents met its primary immunogenicity endpoint, successfully bridging immune response to the adult vaccination. 

The study, called the TeenCOVE study, enrolled 3,700 participants 12 to less than 18 years of age. They received either two 100 microgram doses of the vaccine, mRNA-1273, or a placebo. 

The primary endpoint of the study was non-inferior immunogenicity versus the Phase 3 adult study comparator group.

The study found vaccine efficacy of 93 percent in seronegative participants starting 14 days after the first dose using the secondary CDC case definition of COVID-19, which tested for milder disease.

And after two doses, there were no cases of COVID-19 cases in the vaccine group, compared to four cases in the placebo group. This resulted in a vaccine efficacy of 100 percent starting 14 days after the second dose.

“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 in the announcement. 

“We will submit these results to the U.S. FDA and regulators globally in early June and request authorization. We remain committed to doing our part to help end the COVID-19 pandemic,” Bancel continued.

Overall, mRNA-1273 was well tolerated with a safety and tolerability profile generally consistent with the Phase 3 COVE study in adults. No significant safety concerns were identified.

The most common adverse event was injection site pain. And the most common solicited systemic adverse events after the second vaccine dose was headache, fatigue, myalgia, and chills. 

FDA granted emergency use authorization to mRNA-1273 at the end of December, allowing for national distribution. 

The authorization came weeks after Moderna announced that a second primary analysis of the vaccine was 94.1 percent effective against COVID-19. Vaccine efficiency was observed in a total of 196 cases, of which 185 were in the placebo group and 11 were in the mRNA-1273 group.

mRNA-1273 is currently authorized in Europe, US, UK, Canada, Israel, Qatar, Switzerland, Japan, and Korea.

At the beginning of May, Moderna increased global 2022 capacity for mRNA-1273 to up to 3 billion doses, boosting production at its owned and partnered manufacturing facilities.

The global capacity will be dependent upon the mix between Moderna’s FDA-approved COVID-19 vaccine at the 100-microgram level and the potentially lower doses of the company’s variant booster candidates and pediatric vaccines if authorized.

At the same time, Moderna raised its 2021 manufacturing supply forecast to between 800 million to 1 billion doses.

And most recently, Moderna dosed the first participants in the Phase 2/3 study of mRNA-1273 in children six months to up to 12 years of age.

The KidCOVE study is being conducted with the National Institute of Allergy and Infectious Disease (NIAID) and the Biomedical Advanced Research and Development (BARDA).

Researchers will evaluate the safety, tolerability, reactogenicity, and effectiveness of two doses of mRNA-1273 in 6,750 pediatric participants in the US and Canada. Vaccine doses will be given 28 days apart. 

In part one, participants over two years will receive one to two dose levels at 50 micrograms or 100 micrograms. Younger participants will receive one of three dose levels: 25 micrograms, 50 micrograms, or 100 micrograms. 

In the second part, participants will be followed for one year after the second vaccination. 

Vaccine effectiveness will be determined by achieving a correlate of protection or through immunobridging to the young adult  vaccination, a Moderna spokesperson explained. 

Evaluation of vaccine safety and reactogenicity is also a primary endpoint of the study.