The 'overwhelming majority' of people who have recovered from coronavirus produce antibodies, according to the UK's deputy chief medical adviser.
But Professor Jonathan Van-Tam said it was still too early to say whether these antibodies will make people immune from being re-infected with Covid-19.
Asked about whether the antibodies would lead to immunity, Professor Van Tam told the Downing Street press conference: "We just haven't had this disease around on the planet in humans for long enough."
He said antibodies produced in response to other human coronaviruses "don't persist necessarily for years and years and years", although it is unknown what would happen in the case of coronavirus.
The professor said: "Like everybody else in the world we just have to be patient and cautious until we get those answers."
Matt Hancock, who has recovered from coronavirus himself, was asked by a reporter whether he would currently feel safe to be in a crowded room at the moment.
Honour our NHS heroes – from the surgeons to the porters, the nurses to the catering staff, the physios to the midwives, and the paramedics to the GPs – by helping to create a map of gratitude from every corner of Britain.
We need our health workers now more than ever as they work superhuman hours and go above and beyond to protect us.
Click HERE to drop a heart or a message on the map, and show you appreciate the efforts undertaken daily in the NHS.
You can now also make a donation to NHS Heroes Help From Home, starting from £2.. As a thank you, everyone who donates will be entered into the weekly NHS Heroes Raffle.
Click HERE to donate or to find out more – or click the link from within the Thanks a Million map.
Thanks a million, NHS workers – we love you.
The Health Secretary said he would 'not yet' feel comfortable in that situation, adding: "That might trigger a rise in the number of infections if the science turns out to be wrong."
Mr Hancock is currently taking part in a clinical trial that is looking at the antibodies of patients who have recovered from the virus.
He said that there was positive sounding news about a new antibody test being developed by Swiss company Roche with whom the government are in discussion.
Scientists have discovered an antibody which prevents the coronavirus from infecting human cells in what is being labelled 'groundbreaking research.'
Scientists from Utrecht University in the Netherlands have identified a potential method of neutralising COVID-19 which could lead to the development of new treatments.
They discovered that an antibody which prevents the SARS virus from infecting human cells could also block the novel coronavirus from infecting human cells too, according a peer reviewed study in the journal Nature Communications.