Testing for coronavirus is to be made available to millions of key workers and their families in England, with appointments to be booked online, the health secretary has announced. The system, unveiled at Downing Street’s daily press conference, involves a dramatic expansion of the people who can be tested for the virus, as the government continues to try to reach its target of 100,000 daily tests by the end of April. The government estimates that there are 10 million key workers in the UK who will be eligible for the swab test, which has previously been available only to health workers. The tests will also be offered to the families of key workers, and it is expected that the devolved administrations will follow suit. The health secretary, Matt Hancock, said: “We can make it easier, faster and simpler for any essential worker in England who needs a test to get a test. “Any essential workers who need a test will be able to book an appointment on gov.uk themselves directly. This applies for people in essential workers’ households too, who need a test. It’s all part of getting Britain back on her feet.” The main focus for tests, available from Friday, will be the antigen variety, which tells people whether they currently have the illness. Antigen swab testing can show medics what treatment a patient should receive and who should isolate and who is able to return to work. An antibody blood test showing whether someone has had the illness in the past, which some have argued is more useful, will be used by the government in its forthcoming survey of the disease. The government has so far been under fire for setting an ambitious target of 100,000 tests a day by the end of the month, while drive-through testing facilities have been shown to be underused and difficult for care workers to access if they do not own a car. Capacity currently stands at 51,000 tests a day. In the last 24 hours, 23,560 tests were carried out on 14,629 people. Professor John Newton, director of health improvement at Public Health England, who is coordinating testing, told the press conference that the government was on track to meet its 100,000 target. Contact tracing will be rolled out on a “large scale” with a new NHS app, Hancock said. If you are unwell, you can inform the app, which can let other people with it downloaded know that they have recently been in contact with someone with suspected coronavirus. To “kickstart” tracing, the government will hire 18,000 people, including 3,000 clinicians and public health experts, who will be trained over the coming weeks. The range of jobs classed as essential is extensive, and includes teachers and support staff, people in the justice system, charities, workers delivering key frontline services, transport workers and those working for local government. The process is free and results will be sent out by text, with a helpdesk set up to deal with queries. The shadow health secretary, Jonathan Ashworth, said Labour had consistently asked for a testing and tracing strategy. He said: “It is crucial that greater numbers of critical workers such as care staff are now able to access testing. “We will continue to hold the government to account for the promise it has made of 100,000 tests a day by the end of the month.” Teaching unions and school leaders have welcomed the announcement that school staff will be able to access coronavirus testing, with some calling it an essential precondition before schools are reopened. Paul Whiteman, general secretary of the National Association of Head Teachers, said: “School staff have been on the frontline in the national response to coronavirus. We have been clear from the start that governments across the UK understand they must honour this effort with the appropriate level of support and safety. “If testing can be delivered effectively, then it will be welcomed by the education sector.” Kevin Courtney of the National Education Union said the immediate priority was for teachers who were self-isolating to get tested, and that so far the government had been slow to respond. The number of drive-through test centres will increase from 30 to 48 and the army will run 48 mobile testing units, which will be used to target care homes.