As it spreads, it's mutating, taking on new characteristics, that can make it harder to fight. New variants found in South Africa and the UK are more contageous - straining health services. Japan is trying to isolate a new variant from Brazil. There's no proof any of them are any deadlier, but the virus is constantly changing, and could eventually make vaccines less effective.
South Africa just became the first African nation to surpass the 1 million mark for coronavirus cases, authorities worry about the spread of the new and potentially highly contagious variant detected in the country.