In an open letter published in the British Medical Journal, ministers were warned that urgent action would be needed to prevent further loss of life.
The presidents of the Royal Colleges of Surgeons, Nursing, Physicians, and GPs all signed the letter.
It comes after Boris Johnson announced sweeping changes to England's lockdown.
The Department of Health said it would continue to be guided by the latest scientific advice and would give the NHS "whatever it needs".
On Tuesday, the prime minister said pubs, restaurants, cinemas and hairdressers will be able to reopen from 4 July.
The 2m social-distancing rule will be replaced with a "one-metre plus" rule, meaning people should stay at least 2m apart where possible, but otherwise should remain at least 1m apart while taking steps to reduce the risk of transmission, such as wearing face coverings.
The 2m rule will remain in Scotland, Wales, and Northern Ireland, however.
Both the government's chief scientific adviser Sir Patrick Vallance and the chief medical officer for England Professor Chris Whitty stressed Mr Johnson's plan was not "risk-free" at Tuesday's final daily Downing Street coronavirus briefing.
More about: UK coronavirus
