CNBC reports that Ben Broadbent, the Bank of England’s deputy governor of monetary policy, told  that tight borders following the rollout of vaccines would likely be detrimental to the U.K.’s economic recovery.

Broadbent said the possibility of tight external borders but an internal opening once coronavirus vaccines had become ubiquitous would weigh on the economy.

“One of the downside risks we flagged is the possible emergence of new variants that are less susceptible to the vaccines. We haven’t examined precisely the effects of the different sorts of restrictions,” he said.

“My instinct would be that if you close borders, that would be negative for both the demand and the supply side of the economy.”

Broadbent cited the emergence of new variants of Covid-19 in recent months as a key consideration in the Bank’s outlook.