May 6, 2021 -- The Moderna coronavirus vaccine booster developed specifically to fight the variant first identified in South Africa, works against that strain as well as the variant that originated in Brazil in people already vaccinated for COVID-19, according to results released Wednesday.
Also, data from the company's ongoing phase II study shows the variant-specific booster created more antibodies the South African variant B.1.351 than a booster with the original Moderna vaccine.
"We are encouraged by these new data, which reinforce our confidence that our booster strategy should be protective against these newly detected variants,” Stéphane Bancel, chief executive officer of Moderna, said in a statement.
In the phase II study, researchers also are evaluating a booster for several variants that is a 50-50 mix of the newer formula with the original vaccine in a single vial.
Unlike the two-dose regimen with the original vaccine, the boosters are given as a single dose.
The trial participants received a booster 6 to 8 months after their original vaccination. Antibodies for to the wild-type virus remained high and detectable in 37 out of 40 participants. However, before the booster, antibodies against the two variants of concern, B.1.351 and P1 (which originated in Brazil), were lower, with about half of participants showing undetectable levels.
However, 2 weeks after receiving a booster with the original vaccine or the B.1.351 -specific product, virus neutralizing antibodies were boosted in all participants and against all variants tested.
Both booster doses were generally well tolerated, the company reported. Safety and side effects were generally the same to those reported after the second dose of the original vaccine. Most adverse events were mild to moderate, with injection site pain most common in both groups. Participants also reported fatigue, headache, muscle pain and joint pain.