By Nick Triggle & Oliver Slow
BBC News
Union leaders person agreed nurses tin beryllium called successful during Sunday's onslaught to supply a minimal level of staffing successful intensive attraction and large exigency departments.
A walkout by Royal College of Nursing (RCN) members volition commencement astatine 20:00 BST and tally until the extremity of Monday.
The NHS said "positive discussions" with the RCN had resulted successful agreements to guarantee unit would supply cover.
The authorities has said the escalating onslaught enactment "risks diligent safety".
Sunday's onslaught is the largest concern enactment truthful far, the NHS said, informing patients to expect "disruptions and delays to services implicit the onslaught period".
However, the NHS said discussions implicit the play had secured "a fig of nationalist agreements" to guarantee unit could supply attraction "to support beingness and limb services".
These volition screen intensive attraction units, including for neonatal and paediatric care, arsenic good arsenic immoderate mishap and exigency departments (the BBC understands this volition see large trauma and resuscitation units).
"These mitigations bash not correspond a instrumentality to modular staffing," said Dame Ruth May, main nursing serviceman for England. "The concern enactment volition inactive person a precise important interaction connected services during the onslaught play and patients tin expect to spot longer waits for care."
An RCN spokesperson told the BBC that a "national statement was reached connected raising staffing levels successful immoderate cardinal areas to sphere beingness and limb", adding that this onslaught would beryllium "more intense" than erstwhile ones.
The onslaught was called earlier this period aft RCN members rejected a authorities connection to nurses successful England of a 5% wage emergence for 2023-24 and a one-off outgo of astatine slightest £1,655 to apical up past year's salary, depending connected unit grade.
RCN enactment had recommended members judge the connection but it was rejected by 54% to 46%.
During nursing strikes earlier this year, successful January and February, wider nationalist exemptions were successful place, meaning nursing screen was maintained successful different captious areas.
Health Secretary Steve Barclay said Sunday's escalating onslaught enactment "risks diligent safety".
"These strikes volition enactment much unit connected the NHS and volition beryllium incredibly disruptive for patients," helium said.
The concern enactment comes up of a important gathering betwixt unions, ministers and NHS bosses connected Tuesday.