Experts in Manchester found that a coronavirus vaccine reduced the risk of emergency hospital admission by three quarters in elderly people.
A study by researchers from the University of Manchester and the NHS investigated the impact of the Pfizer vaccine.
It found that older people who had been given the vaccine were less likely to be hospitalised, and less likely to test positive for the virus than those who had not been vaccinated.
The study focused on more than 170,000 people aged from 80 to 83, who received the Pfizer/BioNTech vaccine jab between December 15 and 20 last year.
They were compared to another group of 'matched controls', people aged 76 to 79 who had not been vaccinated.
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After 21 days, hospital admissions reduced by 50 per cent in the vaccinated group compared to the unvaccinated group.
Infections were also down by 55 per cent.
And the study found that between 35 and 41 days after people had been vaccinated, emergency admissions were then 75 per cent lower in the vaccinated group.
Positive tests were 70 per cent lower in the vaccinated group, compared with the unvaccinated group.
Simon Stevens, chief executive officer of NHS England, spoke about it at a Health Service Journal leadership event, where he said the vaccination program is going 'extremely well'.
He said: "Vaccines are successfully reducing hospitalisations and deaths amongst the cohorts that have had the vaccine.
"Data that we have analysed shows a 75 per cent reduction in emergency Covid hospitalisations for the vaccination cohorts and, as more and more people are vaccinated, that effect will widen.
"So, with the next step of the opening process that began on Monday, we obviously have to track very carefully what that means for infection rates.
"In terms of the vaccination programme, that is going extremely well and it’s a huge credit to everybody involved."
The latest figures show that almost 34 million people have now received a coronavirus vaccine.
Trials are also underway to determine whether people can be given doses of two separate jabs.