Japan has found a new Covid variant. Here's how it compares to virus strains in the UK, South Africa

The identification of a new Covid variant comes as countries scramble to contain two other contagious strains that have emerged in the U.K. and South Africa. Public health experts have expressed concern the fresh strains could pose a threat to inoculation efforts. In recent weeks, optimism about the mass rollout of coronavirus vaccines appears to have been tempered by the resurgent rate of virus spread worldwide.