Britain is tightening border controls to block new variants of Covid-19, suspending all “travel corridor” arrangements that had meant arrivals from some countries did not require quarantine.

Prime Minister Boris Johnson is grappling to control a third wave of the virus and prevent the health service from collapse while also racing to vaccinate millions of citizens each week.

“What we don’t want to see is all that hard work undone by the arrival of a new variant that is vaccine-busting,” he told a news conference, explaining the end of travel corridors at least until Feb. 15.

The rule changes come into force at 0400 GMT on Monday and mean all passengers must have a recent negative coronavirus test and transfer immediately into isolation upon arrival.

Isolation lasts for 10 days, unless the passenger tests negative after five.

On Thursday, Britain banned arrivals from South America, Portugal and some other countries over fears about a variant detected in Brazil.

Britain has already felt the effects of mutations in the virus first hand. A variant first discovered in England has proved to be more transmissible.

Critics say the government has been too slow to act and previously left borders wide open.

Much of the criticism prior to Friday’s announcement has focused on whether rules requiring arriving passengers to quarantine are actually being enforced, with anecdotal evidence that few checks are made.

“We will be stepping up our enforcement, both at the border and in country,” Johnson said.

(Reporting by Sarah Young; Writing by William James; Editing by Elizabeth Piper and Andrew Cawthorne)

This article was written by Sarah Young and William James from Reuters and was legally licensed through the Industry Dive publisher network. Please direct all licensing questions to legal@industrydive.com.

Photo Credit: All passengers flying into the UK will be required to have a recent negative coronavirus test and transfer immediately into isolation upon arrival. Matthew Childs / Reuters