More schools have shelved plans to reopen on Monday after new data suggested coronavirus could still be spreading in the north-west of England. Health officials at Blackburn with Darwen council, which runs 85 schools in Lancashire, emailed on Friday evening advising them not to reopen on Monday morning. Public health officials in Tameside, Greater Manchester, also advised schools to delay reopening for pupils other than vulnerable children and those of key workers until 22 June. It comes after new data showed the virus’s reproductive rate, known as the R value, was higher than the crucial threshold of 1 in the north-west. The R value refers to the average number of people that will contract coronavirus from an infected person. If it is 1 or higher, the virus will spread exponentially through the population, while a value lower than 1 indicates the virus is in decline. Officials from Queen Elizabeth grammar school in Blackburn (QEGS) tweeted that it would not reopen until 22 June, after latest guidance from the council to all schools across the borough. The headteacher, Claire Gammon, wrote a statement on the school website to parents and carers. It said: “Following updated guidance from Blackburn with Darwen council this evening, we are delaying the phased reopening of school until 22 June 2020. We appreciate this is late notice, however we are having to work with an ever-evolving situation and flexibility is required by our whole QEGS community.” Other schools in the borough, which has a population of 150,000, said teachers were devastated after working tirelessly to prepare for Monday. The north-west has the highest rate of Covid-19 infections in England according to Public Health England (PHE), and data released on Friday afternoon suggested the R value was higher than 1 in the region. Data released on Friday gave an R value of 1.01 for the north-west and 1.0 for the south-west. All other regions were below 1. The government has suggested a strategy of “local lockdown” measures to fight any flare-up of the virus in particular areas. Andy Burnham, the mayor of Greater Manchester, has questioned whether such measures are workable, calling them a recipe for chaos. Both he and the Liverpool city region metro mayor Steve Rotheram have raised concerns lockdown is being relaxed too soon. Council bosses in Liverpool and Gateshead led a northern backlash against the government announcement last month advising schools to reopen for years 1 and 6 from 1 June. The health secretary, Matt Hancock, speaking at the Downing Street briefing on Friday, said experts on the Scientific Advisory Group for Emergencies (Sage) believed the UK’s overall R number was below 1, but added that local lockdowns would be used when outbreaks were spotted. He said the PHE data needed to be looked at “in the round” with other data. “The discussion of the higher R in the north-west and the south-west that’s estimated compared to the rest of the country is an important part of moving towards a more localised approach rather than a national approach to the lockdown,” he said. Tameside council’s director of public health, Jeanelle de Gruchy, said in a letter to to headteachers that after initially supporting the gradual reopening of schools, the advice had changed. “Because of this change in R, and despite the excellent work undertaken, I am therefore strongly advising all schools and childcare settings to delay wider opening until at least 22 June for us to be more assured that the rate of infection is reducing and R is firmly below 1,” she wrote. Colin Cox, the director of public health in Cumbria, said on Friday that people should not be complacent and that lockdown restrictions could be tightened if the R number increased.