People sit outside the Bullring shopping centre in Birmingham, central England on August 22, 2020. (Photo by JUSTIN TALLIS/AFP via Getty Images)

Authorities in Britain’s second city of Birmingham announced new coronavirus restrictions Friday as the nation’s viral reproduction rate, or R number, exceeded 1.0 for the first time since March.

From next Tuesday, more than 1.1 million people will be banned from mixing with any other household, after the rate of infection in Birmingham 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.”

He added: “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.”

Britain has suffered the deadliest outbreak of Covid-19 in Europe. Another six deaths were reported on Friday, taking the total to 41,614.

Cases fell over the summer months but are now rising sharply, with 3,539 new infections recorded Friday — the highest daily figure since May 17, bringing the total to 361,677.

The government confirmed the trend Friday by saying the R number was now 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.

In response, coronavirus rules were tightened across the country this week, with England and Scotland notably announcing bans on meetings of more than six people from different households.

Separately, data on Friday 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 new 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.”