Care home staff in England may be required to have a Covid-19 vaccine to protect residents from the virus, the government has announced.

A five-week consultation will be launched on Wednesday. Matt Hancock, the health secretary, said the government had “a duty of care to those most vulnerable to Covid-19”.

The Department for Health and Social Care (DHSC) said experts on Scientific Advisory Group for Emergencies (Sage) advised 80% of staff and 90% of residents need to be vaccinated to provide a minimum level of protection against outbreaks.

But warned only 53% of older adult homes in England are currently meeting this threshold.

The DHSC said it meant nearly half of all care homes with older adult residents, home to 150,000 vulnerable people, do not meet the recommended vaccination thresholds for care homes and staff.

Currently the staff vaccination rate is below 80% in 89 local authority areas – more than half – and all 32 London boroughs. There are 27 local authority areas with a staff vaccination rate below 70%.

Christina McAnea, the general secretary of the Unison union, said mandatory jabs were “the wrong approach and a massive distraction”.

“Targeting adverts at care staff, lining up already-jabbed colleagues to offer reassurance, tackling misinformation and giving staff time to make the right decision is where the government should be concentrating its efforts. It’s what’s worked in the NHS and in other countries,” she said.

“Too heavy handed an approach could backfire badly. Some staff may simply up and go, leaving a poorly paid sector already struggling with thousands and thousands of vacancies in a terrible state. That could damage the quality of care for the elderly and vulnerable, and no-one wants that.”

Hancock said: “Older people living in care homes are most at risk of suffering serious consequences of Covid-19 and we have seen the grave effects the virus has had on this group.

’Making vaccines a condition of deployment is something many care homes have called for, to help them provide greater protection for staff and residents in older people’s care homes and so save lives.

“The vaccine is already preventing deaths and is our route out of this pandemic. We have a duty of care to those most vulnerable to COVID-19, so it is right we consider all options to keep people safe.”

It comes after Boris Johnson said on Tuesday that although vaccines had helped, lockdown restrictions had done “the bulk of the work” in reducing infections.

And the prime minister warned that the easing of lockdown restrictions will “inevitably” lead to more infections and deaths.

The number of vaccine doses administered in the UK has passed 40 million, of which nearly eight million are second doses.

People aged 45 and over in England are now also being invited to make appointments for their vaccination.