As the UK sees a rise in coronavirus cases, officials are warning that "people have relaxed too much."
The United Kingdom recorded 2,988 new Covid-19 cases in a 24-hour period on Sunday -- the highest daily number since May. Another 2,948 new cases were reported on Monday.
Deputy Chief Medical Professor Jonathan Van Tam said the rise in cases was "of great concern."
Speaking to the BBC, Van Tam said that although people had been able to "relax a bit over the summer," with disease levels low following lockdown, "these latest figures really show us, as much as people might like to say, 'Oh well it’s gone away' -- it hasn’t gone away."
"People have relaxed too much, and now is the time for us to re-engage and realize that this is a continuing threat to us," he warned.
"Don't kill your gran": Health experts and officials have directed many of their warnings towards young people.
"The rise in the number of cases we've seen over the last few days is largely amongst younger people … under 25's – especially between 17 and 21," Health Secretary Matt Hancock said in an interview with LBC radio on Monday, adding the rise has been most noticeable among “more affluent, younger people”.
He said even though younger people are at lower risk of dying from Covid-19, there is a risk that they could infect other people.
In an interview with Sky News, Housing Secretary Robert Jenrick warned young people who are "out enjoying themselves" to exercise caution "particularly when they go home and see their elderly relatives."
Hancock echoed a similar sentiment, telling BBC Radio 1's Newsbeat's listeners: "Don't kill your gran by catching coronavirus and then passing it on."
But some have complained that the government's messaging has been confusing.
In August, the UK government ran an "Eat Out to Help Out" scheme encouraging people to use restaurants, cafes and pubs -- which some say undermines efforts to curtail the virus.
And Prime Minister Boris Johnson has been encouraging people to return to work since May.
UK universities are also set to resume classes soon -- despite Hancock's comments that students going back to university are a "concern."
"For ministers and universities to rely on the behaviour of students, rather than deploying the public health infrastructure needed to control the virus, is a complete shirking of their own responsibility," Jo Grady, general secretary of the University and College Union, said in a statement.
"Students have been told to move, live, study and socialise together," Grady added. "It is totally unacceptable for Matt Hancock to try and suggest that they will be at fault for any second wave."