Moderna said Monday it’s accelerating work on a Covid-19 booster shot to guard against the recently discovered variant in South Africa. Its researchers said its current coronavirus vaccine appears to work against the two highly transmissible strains found in the U.K. and South Africa, although it looks like it may be less effective against the latter. The two-dose vaccine produced an antibody response against multiple variants, including B.1.1.7 and B.1.351, which were first identified in the U.K. and South Africa, respectively, according to a Moderna study conducted in collaboration with the National Institute of ... (full story)