People may not need to self-isolate if they have been in close contact with someone with Covid, if a new trial is successful.
The government-backed research will trial giving people daily lateral flow tests for seven days - instead of quarantining for 10 days.
From 9 May, about 40,000 close contacts of people with Covid in England will be invited to take part in the study replacing quarantine with daily testing.
As part of this major new study, people will have to test themselves every morning for seven days and will be exempt from the legal requirement to quarantine at home every day they test negative, as long as they do not show any symptoms of Covid.
Between May 2020 and April 2021 in England, more than 6.7 million close contacts were reached and told to self-isolate, NHS Test and Trace data shows.
Men, younger people and parents with young children were less likely to self-isolate - as were those from more working-class backgrounds, people in financial hardship and key workers.
She said the study needs to recruit such a large number of people, who will be invited as part of the contact tracing process, because infection rates are relatively low at the moment.
As well as the daily lateral flow test, study participants will take a more accurate PCR test at the beginning and end of the trial period.
They will also take a PCR test if any of the daily tests gives a positive result.
Health Secretary Matt Hancock said: "This new pilot could help shift the dial in our favour by offering a viable alternative to self-isolation for people who are contacts of positive Covid-19 cases, and one that would allow people to carry on going to work and living their lives.".
She said many people also had to self-isolate unnecessarily, "which has really stopped life in the UK over the past year".
While lateral flow tests are not as accurate as the PCR swabs used at testing centres, their use by schools to safely reopen has shown they can be effective, Dr Cannon said.
Prof Peter Openshaw, an immunologist who advises the government, said the tests were "contentious" but used daily, were likely to catch the people "most prone to spreading disease".
But asked if the UK should pause the vaccination of younger, less vulnerable people to send doses abroad, the foreign secretary said he has not received any request from India "on that specific issue".
Shadow foreign secretary Lisa Nandy said the issue is "deeply personal" as she has a close family member in hospital with Covid in India, but added the UK should not pause the vaccination of younger people to send vaccines overseas.