AUTHORITIES in Britain's second city of Birmingham announced new coronavirus restrictions on Friday (11) as the nation's reproduction rate, or R number, exceeded 1.0 for the first time since March.
From next Tuesday, more than 1.1 million people are banned from mixing with any other household, after the rate of infection rose from 30 to 75 cases per 100,000 people over a week in August.
"I know this is difficult, particularly when we have got used to seeing friends and family," said Ian Ward, leader of Birmingham City Council.
"But it is vital we stick to these rules and protect each other given the sudden rise in infection rate.
"The virus has not gone away, it has not weakened, in fact it is relentless and we must be relentless in our efforts to control the spread."
Coronavirus rules were tightened this week to ban meetings of more than six people from different households, owing to a nationwide rise in cases.
On Friday, the government said at least 41,600 people had died in the Covid-19 outbreak, and numbers were growing again with an R number of 1.0 to 1.2 across the country.
The reproduction rate measures the number of people in a population, on average, infected by each person carrying the virus. Any number above 1.0 indicates the disease is expanding.
Separately, the latest data from a survey of over 150,000 volunteers by Imperial College London put the R rate at 1.7 in England, and they warned that cases were doubling every seven to eight days.
A mass testing scheme for the health ministry found there were 13 people infected per 10,000 in England -- up from four per 10,000 at the beginning of August.
"We are now entering a phase of increasing transmission as we head into the autumn," noted Professor Azra Ghani, chair in Infectious Disease Epidemiology at Imperial.
"What is particularly concerning is the widespread nature of this increase, with infection no longer confined to localised areas or identified clusters.
"In this circumstance, broader national social distancing measures -- such as those recently announced -- are required to interrupt transmission and slow the growth of the epidemic."