South Africa has suspended use of the AstraZeneca/Oxford University vaccine following data showing that it was ineffective at preventing moderate disease caused by a variant of COVID-19 first identified in that country. Researchers believe that it could still be able to protect against severe disease, but the trial participant pool – which was small to begin with, at fewer than 2,000 – skewed too young to conclude that. Other vaccines that are less effective against localized variants still show good evidence of protecting against severe disease.