The easing of restrictions on May 17 will likely cause an increase in infections across England but not enough to overwhelm the NHS, scientists advising the Government have said.

Modelling has shown that England’s R number will probably rise above 1 when lockdown measures are relaxed under stage three of the Government’s road map, the Scientific Advisory Group for Emergencies (Sage) said.

While it means that Covid-19 infections will increase across the country, it is “highly unlikely to put unsustainable pressure” on the NHS, the group concluded at its meeting on May 5.

Sage said it remained “highly likely” there will be a further resurgence in hospital admissions and deaths “at some point”, and that the full impact of easing restriction will not be seen until mid-June at the earliest.

But that resurgence will be smaller if measures that reduce transmission, such as social distancing, are maintained beyond the end of the Government’s road map on June 21.

“If baseline policies to reduce transmission are kept in place at the end of the road map, behaviour does not return to pre-pandemic levels, and vaccine rollout is not substantially slowed, there is an opportunity to keep the resurgence small,” Sage said.

Modelling has also shown lower peaks for hospital admissions and deaths, compared to previous waves, as evidence suggested that the vaccine may have a greater impact on transmission than previously thought.

But Sage said that aside from new variants, a low vaccine rollout amongst younger adults and high levels of contact at an early stage were the two “biggest risks” in terms of seeing a larger resurgence of the virus.

It warned that the virus that causes Covid-19 was evolving and it was likely that existing vaccines may fail to protect against transmission, infection and disease in the future.

“Updating the vaccine to keep pace with viral evolution or searching for more broadly protective vaccines are potential solutions to this,” Sage said.

Meanwhile, the emergence of a highly transmissible variant, or one that “evades immunity” could lead to a “very significant” wave of infection, potentially larger than that seen in January this year, if measures are not put in place to control it, the group said.

“Maintaining control of transmission of any such variants will be more difficult when there are fewer measures in place,” Sage added.

It said resources should be targeted towards the early detection of new variant clusters, and ensure that strong measures are put in place over a wide geographical area when one is discovered.