In more vaccine news, Moderna said Monday its COVID-19 vaccine is effective at preventing disease in people infected with new variants of the coronavirus. But Moderna warned the vaccine appears to be less potent against one variant, first discovered in South Africa. Moderna says it’s working on a modified booster shot in case it’s needed to combat the South African variant or other lineages that might evolve further resistance to human immune responses.

Meanwhile, drugmaker Merck has abandoned research into COVID-19 vaccines after two of its candidates failed to provoke a strong immune response in patients enrolled in clinical trials.