A third wave of coronavirus could be triggered by unlocking restrictions too quickly before June, according to the Welsh Government’s scientific advisers.

The Technical Advisory Group’s report states that the increased transmissibility of the Kent variant means that a gradual easing of rules is needed in order to suppress the virus.

The report was made public on Thursday ahead of Friday’s announcement on changes to Wales’ lockdown rules, expected to include the move to a “stay local” requirement and reopening hairdressers and some non-essential retail.

The advice, which was given to ministers last month, says that Wales’ phased return to face-to-face teaching in schools, alongside remaining in Alert Level 3 restrictions until the end of June, could be enough to keep levels of the virus down.

“These scenarios suggest that gradual unlocking of restrictions, combined with a gradual ‘step up’ of children being in school face to face, should be achievable without another wave of cases, hospitalisations and deaths in this period, as long as ‘adherence with restrictions’ remains high,” the report said.

But loosening restrictions early, which were said to include moving to Alert Level 3 from the start of this month and then to Level 2 before the end of June, could lead to a surge in cases.

A combination of restrictions not having the desired effect, plus the new variant having a greater impact on transmission “may produce a third wave where cases are greater than the second Covid wave seen in January”, the report said.

In such a scenario there would be fewer deaths than seen in January due to vaccine protection, it said.

It also states that “all but the most pessimistic scenarios do not see as many deaths as have happened in recent months”.

The reports also advises against relying on vaccinations as a way out of the pandemic, warning that “vaccines are not 100% effective so not all at-risk groups are protected even with full coverage”.

Under a new worst-case scenario for Wales, there would be a further 194,161 cases and 3,496 deaths between February 22 and June 30.

But under a new most likely scenario, it estimates a further 57,866 cases and 806 deaths in that same time.

Wales currently has the lowest rate among the four nations, with 42.8 cases per 100,000 people in the seven days to March 5, the lowest rate since the seven days to September 17.

But health minister Vaughan Gething said on Wednesday that Wales could not move into lower levels of restrictions in line with its previous Covid-19 control plan because the “position has changed and moved on” since the extra transmissibility of the Kent variant was identified.

“We need to take another step back to look at what that then means for measures we take and how quickly we ease out of lockdown,” he said.

“We’ve got clear advice that taking a much more rapid approach would lead to a resurgence with real harm being caused.”

An updated control plan would be published “to take account of the new reality of the Kent variant”, Mr Gething said.