Johnson said a fast-moving new variant of the virus that is 70% more transmissible than existing strains appears to be driving the rapid spread of new infections in London and southern England.
“There’s no evidence to suggest it is more lethal or causes more severe illness,” the prime minister stressed, or that vaccines will be less effective against it.
The Dutch government is already strongly advising its citizens not to travel unless absolutely necessary.
Britain has alerted the World Health Organization that the new variant identified this week appears to be accelerating the spread of COVID-19, saying it accounted for some 60% of the capital's cases.
Viruses mutate regularly, and scientists have found thousands different of mutations among samples of the virus causing COVID-19. But many of these changes have no effect on how easily the virus spreads or how severe symptoms are.
Follow AP’s coverage at https://apnews.com/hub/coronavirus-pandemic and https://apnews.com/UnderstandingtheOutbreak