Scientists at the University of Cambridge was warning the R number coronavirus infection rate may have risen in the Anglia region.
Researchers the MRC Biostatistics Unit at the university have reported that their modelling for the spread of the virus suggests the median R value in the East of England has risen from 0.71 to 0.94 since mid May.
The R value is the reproduction rate of the virus and indicates how fast it is spreading. If R is one it means one infected person will infect one more. If it is greater than one then the disease will spread exponentially.
The Government's scientific advisers believe the rate of coronavirustransmission has not breached the crucial value of one, despite evidence it is very close in some regions.
The Government's value remained between 0.7 and 0.9 for the UK as a whole, though the figure has a two to three week lag, meaning it does not account for the latest easing of the lockdown.
The MRC Biostatistics Unit at Cambridge University is working with Public Health England to model and forecast coronavirus infections around the country. The work is being fed into the Scientific Advisory Group for Emergencies (SAGE) which advises the government.
The research suggests between 490,000 and 657,000 people could have already been infected in the East of England.
The official figure for the number of people who have tested positive for coronavirus is just below 14,500.
The difference in the two number is explained because, for many people, Covid-19 is a mild illness and sufferers may not realise they have had it.
Boris Johnson's plans to reduce the severity of restrictions have allowed forlocal lockdowns to be enforced to prevent the spread.
One crucial means of suppressing transmission is the NHS test and trace system, which seeks to track people down who have come into contact with an infected individual and tell them to isolate.
The Biostatistics Unit reports the East of England may be getting an average 1,660 new infections every day which is a higher figure than the unit reported in mid May.
At that time, it was estimated that the number of people being infected in the region was halving every nine to 11 days. Now the research indicates it would take 49 days for the rate of infections to decline by half.
The Health Secretary and West Suffolk MP Matt Hancock said SAGE believes the R is below one and said local lockdowns would be used when flare-ups are spotted.
Mr Hancock told the Downing Street briefing: "You're right that theR is closer to one in the South West and in the North West, the advice from Sage is that R is below one in all regions.
"However, we want to increasingly have an approach in tackling local lockdowns where we spot a flare-up."
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