The World Health Organization warned countries on Tuesday not to impose blanket travel bans over the new omicron coronavirus variant as governments and scientists try to determine how much protection current vaccines would offer against the strain.
Financial markets fell sharply after the head of drugmaker Moderna said existing COVID-19 vaccines would be less effective against the omicron variant. MSCI's gauge of stocks across the globe shed 1.39% a day after broad declines in Europe and Asia.
BioNTech's chief executive struck a cautiously positive note, saying the vaccine it makes in a partnership with Pfizer would likely offer strong protection against severe disease from omicron, which was first reported in southern Africa a week ago.