Blackburn with Darwen has replaced Bolton as the area of the UK with the highest rate of new cases of Covid-19, with a large number among younger people in both areas. Enhanced surge-testing began in Blackburn on Friday, with council staff door-knocking in areas with high rates, to hand out PCR tests. The army has also been called to staff community hubs to provide test kits. The high rates in Blackburn are particularly among 17- to 18-year-olds, according to the council’s director of public health, who has called for children as young as 12 to be prioritised for vaccines as soon as it is safe. A total of 584 confirmed cases were recorded in Blackburn with Darwen in the seven days to 26 May, Public Health England said. This is the equivalent of 390.1 cases per 100,000 people – the highest seven-day rate for the area since the start of February, according to analysis by the PA Media news agency. Dominic Harrison, the director of public health at Blackburn with Darwen council, said older teenagers were “struggling the most at the moment”. In a tweet on Sunday evening, he said: “[Blackburn with Darwen] rates for 15-19s is raised because of 17-18yo rate of over 1050 /100,000. I think late teenage/young adults are struggling most at the moment – we need 12-18 vaccination prioritised in high-transmission areas as soon as judged safe/effective.” In surge-testing areas, PCR tests will be left for every member of the household, including children over 11. Harrison said the increased testing would aid understanding of how rapidly the variant was spreading across Blackburn. Meanwhile, unions have warned that increased pressure to the local hospital may force the closure of its A&E service and cause delays to test results, including antibody tests, as biomedical scientists began three-week strike action on Monday. Twenty-one scientists employed by East Lancashire NHS Trust, based at the Royal Blackburn hospital and Burnley General Teaching hospital, are locked in a dispute over back pay they say they are owed. Unite regional officer, Keith Hutson, said its members had “faced unprecedented challenges since the beginning of the pandemic”. He said the strike action, which is planned to last until 21 June, would “inevitably cause disruption” across the trust, but that the scientists “feel they have been left with no other option, as management has reneged on its promise to pay the money owed”. East Lancashire NHS Trust did not respond to a request for comment. The seven-day rate in Bolton stands at 386.7 cases per 100,000. This is down from 452.8 on 21 May, and suggests the recent surge in cases in the town, driven by the B.1.617.1 variant, first discovered in India, may have peaked. Dr Helen Wall, the senior responsible officer for the Covid vaccine programme in Bolton, warned against complacency. “I’m pleased to report that things are starting to slow in terms of the rise here in Covid cases, but we really can’t rest on that. It’s only been a few days of the rates slowing down so we really are keen to keep pushing forwards and get the rates down further,” she told BBC Breakfast. Wall said there were very young populations in many of the areas that have recorded the highest rises in Bolton, and each time the age came down for vaccine eligibility thousands more people were able to come forward for the jab. “I think the age of eligibility going down every few days has really helped, and will really help us, if we can get those people through the doors to be vaccinated asap,” she said. Bolton, in Greater Manchester, shares a border with Blackburn with Darwen, which is in neighbouring Lancashire. Both areas have reported some of the highest numbers of cases of the India variant, with Bolton recording 1,354 up to 25 May – the highest in the country – and Blackburn recording 361. Health teams in both local authorities have been running surge testing, along with “surge vaccinations” to boost take-up among everyone who is eligible for the vaccine.