The UK's heath minister warned that coronavirus vaccines may be less effective against new variants of the disease, such as those found in South Africa and Brazil, which justifies stricter border controls.
"We don't know the degree of that," Matt Hancock said in an interview on Sky News on Sunday, commenting on the extent of any potential reduced efficacy of the vaccines. "In the meantime, we've got to have a precautionary principle that says let's not bring these new variants back to the UK."
Hancock's warning came as the UK reported it had vaccinated more than 5 million people, including three-quarters of over 80s. Hancock said the government is conducting a vaccine trial on the South African variant to study its response to the inoculation. Hancock also said he's worried about new variants developing elsewhere in the world.
"The new variant I really worry about is the one that's out there but hasn't been spotted," he said, adding that the UK is offering its genome-sequencing capability to other countries to help them identify new strains.
In the UK's vaccination effort, the supply of vaccines is the rate-limiting factor and not distribution by the National Health Service, Hancock said. He also couldn't confirm that schools would be open again by Easter, saying that the government would have to look at the data around the pandemic at the time.