Jeremy Farrar’s comments came as Home Secretary Priti Patel denounced as “unacceptable” the large gatherings at a number of street parties that have erupted into violence in recent days, according to The Independent.
Patel urged people going out to beaches and parks or protest demonstrations to observe social distancing rules and keep to groups of six or fewer.
But Prime Minister Boris Johnson’s government was accused by the Welsh First Minister Mark Drakeford of fueling the danger of a second spike by encouraging people to behave as if normal life had resumed.
Farrar, the director of the medical charity Wellcome Trust, warned that the reopening of shops, pubs and restaurants would be followed by an uptick in COVID cases in the weeks to come.
He said it was “reasonable” to try to restart the economy, but told BBC1’s Andrew Marr Show, “In truth, the restrictions started to be lifted towards the end of May, the beginning of June, around that bank holiday. I would predict that we will start to see a few increases in cases towards the end of June or the first week of July."
“We’re on a knife edge. [The situation is] very precarious particularly in England at the moment, and I would anticipate we would see an increase in new cases over the coming weeks,” he added.
Drakeford stated that the Welsh government was offering a “much more sober message” than the PM about the move out of lockdown.
“We will continue to do things in the way we’ve done things in Wales – carefully, cautiously, one step at a time,” he told Sky News’s Sophy Ridge on Sunday.
“We put our efforts into planning first and making the announcements second, not making an announcement and then thinking about how you can make those things happen,” he noted.
His comments came as Johnson told The Mail on Sunday of his plans for Britain to “bounce back” from COVID-19, saying he wanted to get the country “as close to normal as possible as fast as possible”.
Drakeford added, “My concerns with the UK government are sometimes less with the substance, where I think we’re all broadly still trying to do the same things, I’m more concerned with the messaging, the way things are described."
“Here in Wales, I am very keen to continue to say to Welsh citizens: ‘Coronavirus has not gone away, it remains something that kills people in Wales every day, if you don’t stay on top of it you will see things going backwards and everything we’ve done together thrown away’," he continued.
“That’s a very different message to the message across the border where the message seems much more ‘it’s all over and you can go back to doing everything as you did before’," he said, adding, “I think we’ve seen around the world how that leads to flare-ups of the disease again.”
Patel insisted the UK government had taken “absolutely the right approach and responsible approach that any government should be taking” to lifting lockdown.
The home secretary urged anyone going out of their homes to observe social distancing rules and not congregate in groups of more than six – including those who want to protest against the killing of George Floyd in the US.
"What we have seen with mass gatherings and protests is unacceptable and the violence against our police officers is also unacceptable," she said, adding, “I would urge people not to participate in gatherings or protests... It’s simply unacceptable to see people gathering in the sort of ways we have been seeing.”
A former chief scientific adviser to the prime minister Mark Walport said that history will judge that the UK went into lockdown too late.
Asked if scientists had got some things wrong, Walport noted, “I think there will be plenty of time to look at inquiries", adding, “I think that did the UK lockdown a bit later than it should, I think history will probably show that it did. I think we’re talking about decisions of days.
“The scientific advice was always very strongly to test,” Walport stated.
He said what also needed to be looked at was the logistics of the response and “how much the UK and other countries paid in the insurance policies in advance to protect against pandemics”.
He added, “I think that what history will also show is that those countries that have experienced previous very nasty … epidemics and infection have been better prepared.”
He noted an important lesson was that “we need to worry a bit more about the next emergency as well as actually being well prepared for the last one”.