Moderna (NSDQ:MRNA) has joined Pfizer (NYSE:PFE) in announcing that its vaccine was 100% effective in a Phase 2/3 study involving adolescents. It will seek regulatory authorization to expand the use of its vaccine to adolescents as young as 12 in early June.
In the TeenCOVE study, no participants who received two doses of the mRNA-1273 vaccine contracted symptomatic COVID-19.
Using a secondary CDC case definition of COVID-19 that includes milder illness, the trial found that the vaccine was 93% effective in seronegative participants. The secondary case definition requires the presence of one COVID-19 symptom and a positive reverse transcription-polymerase chain reaction (RT-PCR) test. The company used that definition because COVID-19 transmission in adolescents is lower than in adults.
Side effects in the trial were generally mild or moderate for v…