The United Kingdom has one of the world's third highest death tolls from COVID-19 but, with infections falling, plans to lift many restrictions from July 4 to help an economy facing the deepest contraction in three centuries.

A major second spike is the nightmare for leaders across the world as they would face blame for more deaths and may have to shutter economies again. Some of Britain's most eminent health leaders, though, want urgent preparations for such a scenario.

"While the future shape of the pandemic in the UK is hard to predict, the available evidence indicates that local flare-ups are increasingly likely and a second wave a real risk," the medics said in a letter in the British Medical Journal.

It was signed by 15 of the most eminent health professional groups and trade unions including the heads of the Royal College of Surgeons, the Royal College of Physicians, the Royal College of Emergency Medicine and the British Medical Association.

"Many elements of the infrastructure needed to contain the virus are beginning to be put in place, but substantial challenges remain," they wrote.

European nations emerging from painful shutdowns are nervously watching a new outbreak at a meatpacking plant in Germany, where two municipalities have regressed to lockdown.

Johnson under pressure

Announcing that England was rising from "hibernation", Johnson is letting pubs, restaurants and hotels reopen from July 4. "While we remain vigilant, we do not believe that there is currently a risk of a second peak of infections that might overwhelm the NHS," he said on Tuesday.

The United Kingdom on Monday reported the lowest daily increase in deaths since lockdown in mid-March - just 15 - though the suspected overall toll has hit 54,139, the second highest after the United States.

Johnson, who was treated in intensive care for COVID-19 complications, has faced criticism from opposition parties for imposing the lockdown too late, failing to supply enough protective equipment and dithering over a test-and-trace system.

The medics' letter called for a review focusing on "areas of weakness" to prevent a second wave in the interests of protecting lives and restoring the economy as fast as possible.

Others signatories included Anne Marie Rafferty, president of the Royal College of Nursing, Maggie Rae, president of the Faculty of Public Health, and Richard Horton, editor-in-chief of the Lancet.

"We need to understand how best to learn from other countries which seem to have managed the crisis differently and perhaps managed it better than we have in the UK," Martin Marshall, president of the Royal College of General Practitioners, told the BBC.