Britain on Thursday announced it had signed deals to buy more than 10 million coronavirus antibody tests from pharmaceutical firms Roche and Abbott for distribution to frontline healthcare workers.

“From next week we will begin rolling these out in a phased way, at first to health and care staff, patients and residents” of care homes, Health Secretary Matt Hancock said.

Speaking at the government’s daily coronavirus briefing, he said: “This is an important milestone and it represents further progress in our national testing programme.”

He cautioned that it was not yet confirmed that having COVID-19 antibodies conferred immunity, but said the tests would help better understand the disease.

Hancock also revealed that around 17 percent of people in London, and around five percent or higher elsewhere in the country, had tested positive for coronavirus antibodies, according to a small population sample.

Britain has recorded the highest number of deaths in Europe from coronavirus, with more than 36,000 people who have tested positive having died so far.

Like many countries, however, it is gradually easing a nationwide stay-at-home order imposed at the end of March.

After being criticised for a slow initial response to the outbreak, Prime Minister Boris Johnson — who himself was hospitalised with coronavirus — has promised a “world-beating” tracing strategy by the beginning of June.

A smartphone app is currently being tested, while the government has also promised to recruit 25,000 tracing staff.