Researchers in Houston say the coronavirus is mutating into a new strain - one that's more resistant to facemasks and hand-washing.
The mutation, known as D614G, carries a higher viral load and is potentially more contagious - but not deadlier - than the current strains.
Scientists say the D6146G mutation accounted for more than 99% of samples taken from the Houston area in June, accounting for the so-called 'second wave' of infections in the summer months.