Norfolk care home owners have said isolation levels have dropped to "virtually zero" in the wake of the vaccine rollout.
It comes as a study led by researchers at University College London has found a single dose of the Pfizer or AstraZeneca vaccine was effective at stopping 62pc of infections in care homes.
The study examined data of 10,412 elderly care home residents from 310 care homes between December and mid-March. examining PCR tests.
They calculated the risk of infection was 56pc lower from four weeks after a single dose of either the Pfizer or Oxford-AstraZeneca vaccine, and 62pc lower after five weeks.
Raj Sehgal, of ArmesCare, which has four homes in West Norfolk has between 91pc to 100pc of home residents have received their two Covid jabs.
Staff receiving their second jab are being staggered with numbers requiring their second dose between 10 and 68pc, with staff isolation levels falling to "virtually zero" and was encouraging those staff that had not taken up the vaccine that it was in the "best interests of their own health and the nation".
He said: "Isolation levels have dropped to virtually zero as most people have been adhering to national lockdown restrictions.
"We are hopeful that with ongoing weekly LFT & PCR testing, we should be able to keep our staff safe and ultimately keep the disease out of our homes."
At Barchester Healthcare, which has six care homes around Norfolk and Waveney, 92pc of residents and 90pc of staff have had their first vaccine. 42pc of residents and 32pc of staff have had their second jab.
A spokesman for the group said it welcomed the additional protection the vaccine, adding; "These vaccinations, in conjunction with the hard work of our staff, means we have very few residents or patients (currently around 0.1%) who have tested positive for COVID-19 through our continued regular testing, and the majority of those that have tested positive are either asymptomatic or have very mild symptoms."
Georgina Johnston, regional operations director for Kingsley Healthcare, said there has been a significant reduction in the infection rate and no large scale outbreaks.
She said: "We have seen reductions in staff absence and isolation. The vaccine take-up has been a great success with 94pc of staff vaccinated.
"We have seen no large-scale outbreak; a couple of homes have seen residents testing positive but remaining asymptomatic. It has not spread around the home like it did pre-vaccination."
Since March 8, homes has welcomed back family members under the government's roadmap, with care providers able to welcome named visitors into the home for the first time.
The research also found among care home residents who had previously contracted coronavirus, a single vaccine dose appeared to have little impact, suggesting they were already well protected.
Further research is also needed to examine how effective a first dose is after eight to 12 weeks, and the impact of a second dose.
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