Moderna’s version of a COVID-19 vaccine is proven to demonstrate 93% efficacy against symptomatic disease in a 6-month window, according to the company. The data was derived from a thorough analysis of the vaccine’s COVE Phase 3 study. Thousands of early dose-eligible participants who received both shots last year were monitored for six months after their second jab in the assessment. None of this research includes data about the current Delta variant surge, as these findings long predate its emergence.
The mRNA vaccine from Pfizer/BioNTech produced a similar 91% six-month efficacy rate that does not account for the Delta variant -- with one notable, time-related difference. Pfizer’s trial saw efficacy peak at over 96% in the short period following the second dose, but protection dwindled to 83.7% four to six months later.
Moderna has indicated that the Delta variant will most likely stir up a need for booster shots among vaccinated individuals, and those would be especially essential with the coming of the winter season. The company is still determining if the booster should require 100 micrograms like the initial doses, or come in the form of a lessened, 50-microgram load.