The second wave of Covid-19 will be “gruelling” with increased pressure prolonged throughout winter, UK doctors have been warned.

Chief medical officers and other senior health figures have written to doctors urging them to be flexible as they may be required to work in clinical areas outside their usual practice.

The letter, tweeted by England’s chief medical officer Professor Chris Whitty, said the second wave “may well be prolonged throughout the winter period, with wide local variation and fluctuation in cases, requiring a sustained response from the whole profession”.

It warned: “This will be gruelling professionally and personally.”

It added that pressure will “inevitably be exacerbated by staff shortages” due to sickness or caring responsibilities, and assured doctors that regulators will take into account the need for temporary changes to practice.

Healthcare professionals will have to be “flexible”, which “may entail working in unfamiliar circumstances or surroundings, or working in clinical areas outside of their usual practice”, the letter said.

It added: “This can be stressful and you may have concerns about both the professional practicalities and implications of working in such circumstances.”

Hospitals, trusts and healthcare leaders have been told to “bear in mind that clinicians may need to depart, possibly significantly, from established procedures in order to care for patients in the highly challenging circumstances of the epidemic”.

Healthcare regulators, including the General Medical Council, have committed to “take into account factors relevant to the environment in which the professional is working”, the letter said.

It added that coronavirus restrictions imposed across the UK will result in the initial peak of pressure on the healthcare system being “significantly lower” than it otherwise might have been.

The letter said “We all need to support one another during this time. It is, and is going to remain, hard going but mutual support makes this prolonged crisis easier to manage personally, as well as professionally.”

The chief medical officers of England, Scotland, Wales and Northern Ireland, the NHS, the GMC and the medical royal colleges all signed the letter.