With infections rising throughout Britain, England’s chief medical officer, Chris Whitty, warned Monday that the next few weeks could be the “worst” of the pandemic, and British Prime Minister Boris Johnson asked the public for “maximum vigilance.” Tougher measures could be necessary if cases continue to rise, he said. Speaking to the BBC, Whitty said Britain is in greater danger from the virus than before and urged the public to alleviate pressure on the country’s increasingly overburdened National Health Service by “minimizing the amount of unnecessary contacts.”

The new, highly transmissible variant of the coronavirus, which has been reported in more than 30 countries, is “everybody’s problem,” he said, adding that “the next few weeks are going to be the worst weeks of this pandemic in terms of numbers into the NHS.”

A stricter lockdown could mean that people are no longer allowed to exercise outdoors with others from outside their households or see people who are part of their “support bubbles,” the Guardian reported. At a news conference Monday evening, British Health Secretary Matt Hancock outlined the government’s plan to vaccinate at least 15 million people in high-priority groups by mid-February.

With seven mass vaccination sites opening across England and a team of 80,000 trained volunteers on hand to help administer doses, Hancock said, officials were dedicated to making vaccinations happen “as fast as we can.”