Coronavirus infections among the most vulnerable age groups in Norfolk has dropped by 75pc in just over a month, suggesting the vaccine rollout may be starting to have an impact.

Prime Minister Boris Johnson said this week that there were “interesting straws in the wind” and “grounds for confidence” on vaccines cutting the spread of infection.

Vaccines minister Nadhim Zahawi, meanwhile, told Times Radio that data on the vaccines' impact on hospital admissions and severe illness would be released before the government announces its road map out of lockdown on February 22.

He said early data on the effect on transmissions was "really encouraging".

Separately, the Office for National Statistics released figures on Tuesday showing that the age group most likely to have coronavirus antibodies were the over 80s.

People test positive for antibodies either if they have been infected with Covid in the past few months or if they have been vaccinated.

Around 40pc had the antibodies which the ONS said was "most likely due to the high vaccination rate".

Since December, around a third of the population of Norfolk and Waveney has been vaccinated, including 94pc of over 80s and 97pc of people aged 74-79.

Data shows infection rates have fallen sharply among those older age groups since January 8 – the start of the Oxford vaccine rollout.

Rates among over 90s have plummeted by 77pc.

The rate among people aged 85-89 and 80-84 fell by 79pc and 83pc in the same period.

But despite the good news, it is hard to pinpoint whether it is the vaccine rollout or the impact of lockdown which is driving the figures down.

In the same time infections among the under 60s, very few of whom have had vaccines, also dropped by 75pc.

Professor Paul Hunter, from UEA’s Norwich Medical School, said he thought it was too early to point to the vaccine rollout as the source rather than general lockdown restrictions.

But, he added his own research was beginning to offer some promising signs.

Norwich Evening News: Paul Hunter, professor of medicine at the UEA, believes it is the right time for increased social interaction between households amid the coronavirus pandemic. Picture: ArchantPaul Hunter, professor of medicine at the UEA, believes it is the right time for increased social interaction between households amid the coronavirus pandemic. Picture: Archant (Image: Archant © 2013)

"It does look like we’re starting to see a noticeable decline in the older age groups, relatively speaking, particularly in the over 80s, and we’re possibly starting to see that in (reducing) hospital admissions.”

The number of Covid patients in the county’s hospitals has dropped by a third since January 8 and Professor Hunter said his research was showing that fewer older people were being hospitalised with Covid.

“The data is quite noisy and has jumped around a bit in the past, but although it is difficult, what we can see is that the seven-day ratio of hospital admissions is drifting downwards,” he said.

Deaths fall twice as fast in over 80s

So far, the number of weekly hospital deaths in Norfolk has remained steady, although the figure has fallen since the peak of the latest wave.

NHS numbers show 108 people died with coronavirus in the week leading to February 10, slightly up on the 94 in the seven days to January 8.

But national research by the University of Oxford suggests deaths in the over 80s bracket have fallen twice as quickly as in the under 65s.

Since the peak in January, deaths among the older age group have fallen by 32pc, compared to 14pc in the younger bracket.

The Oxford team from the Centre for Evidence Based Medicine (CEBM) said results were “tentatively consistent with the impact of vaccination”.

And the vaccine does finally seem to be having an affect on deaths in Norfolk’s care homes, with 31 recorded in the week ending February 12, compared to 54 the week before, and more than 100 the week before that.

So when will we see a definite impact?

It takes up to three weeks for the vaccines to give protection, so people who were vaccinated on January 8 – the first day of the Oxford jab rollout – would not have been protected until January 29.

Experts have predicted the vaccine impact will start to have a definite effect on hospitalisation cases four weeks after the people who have received the first dose reach ‘peak protection’, which takes us to February 26.

The impact on deaths will be seen after five weeks, which would fall on March 5 – eight weeks after the beginning of the Oxford jab rollout.