The impact of coronavirus vaccinations in the over-80s should be seen “over the next two weeks”, the Covid-19 strategic response director at Public Health England has said.

Dr Susan Hopkins said rates a declining “in all age groups” currently but it’s “a bit early to say” if the trend is due to the vaccine or more stringent lockdown measures.

Speaking to the BBC One’s Andrew Marr Show, Hopkins said: “What we would like to see is a divergence in the case rate in the over-70s and over-80s who have been vaccinated from the younger age groups, to show that they are declining faster.

“We have now hit 80% of the over-80s being vaccinated and really fast numbers climbing in the under 80-year-old age group as well.

“We expect over the next two weeks to start seeing that impact of that vaccine in that age group, and also an impact on hospitalisation.”

Michael Gove on Saturday said the government is “fully on course” to hit its target of vaccinating the 15 million most vulnerable individuals in the UK by mid-February, as official data showed 8,378,940 had received first doses.

But the daily increase of 487,756 first doses came as ministers announced a further 1,200 people had died within 28 days of testing positive for Covid-19 as of Saturday, bringing the official UK total to 105,571.

Hopkins also warned that relaxing lockdown measures would have to be done “very slowly, very cautiously” to avoid a surge in infections.

“We have learnt, as we did on the first occasion, we have to relax things really quite slowly, so that if cases start to increase we can clamp down quite fast,” she said.

“The NHS is going to be under pressure until the end of March, as normal in winter, but even more so with the amount of inpatients they still have with Covid-19.

“Any releases that we have will have to happen very slowly, very cautiously, watching and waiting as we go, with a two-week period to watch and see the impact of that relaxation because it takes that to see what’s happening in the population.”