The move will enable local leaders to seek further support from the government, the group –made up of members of the NHS, emergency services and local authorities – said.
A “major incident” has been declared by local authorities in Essex, amid increasing pressure on local health services.
The move was made in response to “significant growing demand” on hospitals across the county caused by the coronavirus pandemic, the Essex Resilience Forum (ERF) said.
Major incidents have also recently been declared at hospitals across London.
In neighbouring Essex, ERF said on Wednesday the number of patients in the county receiving treatment for coronavirus had increased to levels exceeding those seen at the peak of the first wave.
The group added that such numbers were expected to increase further in the coming days and that cases were particularly high in Mid and South Essex.
Areas of concern included critical care and bed capacity, staff sickness and the ability to discharge patients quickly into safe environments.
“Declaring a major incident enables us to seek further support from the government to address the severe pressures which the health system is under because of Covid-19,” the chief constable of Essex Police and ERF co-chair, BJ Harrington, said.
“The people of Essex have been magnificent and are only dialling 999 or attending A&E in an emergency – we need this to continue because this will help protect the very limited capacity available at our hospitals.”
Anthony McKeever, executive lead for Mid and South Essex Health and Care Partnership, said: “We are taking every action possible within the NHS and across the wider health and social care partnerships in Essex to limit the impact on the NHS and the wider health system.
“This involves using critical care capacity elsewhere in Essex and the Eastern region and identifying additional locations and capacity to assist with the discharging of patients to reduce pressure on hospitals.”
More than 20,000 Covid-19 patients were in hospitals in England on Monday and Tuesday – up from an April peak of 18,974.