Coronavirus cases in England are at their lowest level since last August, indicating the success of the vaccine rollout despite the relaxation of lockdown, new data suggests.
There were marked reductions in COVID-19 prevalence from March to April and early May across the country, according to data from the latest round of the React-1 study.
Between the last round which looked at data from March, and the current round which looked at data from April to the beginning of May, swab-positivity dropped by 50% in England from 0.20% to 0.10%.
Experts estimate the corresponding R number to be 0.90.
The data includes 127,408 coronavirus swab tests carried out across England between 15 April and 3 May.
Researchers found there was a fall in all age groups except the 25 to 34-year-olds, with a "significant" fall in the 55 to 64-year-olds.
Professor Paul Elliott, director of the React programme, told a press briefing: "This coincides with the rollout of the vaccine programme to the younger part of that age group."
The data also suggests higher prevalence among the Asian community.
Researchers say the divergence between the pattern of infections and a pattern of hospital admissions and deaths suggests the rollout of mass vaccination is preventing severe outcomes.
Steven Riley, professor of infectious disease dynamics, Imperial College London, said: "What you can see in recent times – basically since the widespread rollout of the vaccine – and we showed this last time, that you see a decoupling of the relationship between the React infection and a lagged number of deaths.
"And this gap is showing how we can have more infections in the population with far fewer deaths.
"And we actually see that difference growing nicely now for hospitalisations as well, so for each infection in the community we are producing fewer hospitalisations and far fewer deaths."
Health Secretary Matt Hancock added: "Today’s findings demonstrate the impact our incredible vaccination rollout is having on COVID-19 infection rates across the country, with prevalence lowest amongst those more vulnerable people aged 65 and over."
Asked whether the data supported a move into the next stage of easing lockdown restrictions, Prof Elliott said: "It is a difficult question because we have low levels of prevalence in the community, and we’ve got low levels of disease in hospitals and deaths, so that’s good.
"But I think that the patterns in the Indian variant are cause for some concern."
He added that further studies are needed to really understand the characteristics and the spread of the Indian variant which appears to be at least as transmissible as the Kent variant.
Meanwhile, preliminary data in mixing vaccines has found an increased frequency of mild to moderate symptoms in those who received different jabs for the first and second dose.
The Com-Cov study was launched in February to investigate alternating doses of the Oxford/AstraZeneca and Pfizer Covid-19 jabs, with either being given as the first dose, and then the other as the second.
Reactions included symptoms like chills, fatigue, headaches and feeling feverish, and were short-lived, according to a peer-reviewed letter that has been printed in The Lancet.
There were no other safety concerns, researchers found.