As many as 80% of people who tested positive for coronavirus during a study of the pandemic in England had not displayed any symptoms, the health secretary has said.
The Office for National Statistics (ONS) has been carrying out a survey using swab testing to determine how many people from across the country at any one time are infected with Covid-19.
In the vast majority of cases, said Matt Hancock, those who had tested positive had not been presenting any symptoms.
Speaking at the daily Downing Street briefing, the Cabinet minister said: “The big-picture answer is that yes there are some people who don’t have symptoms but do have the virus.
“And in fact, in the ONS study we find that around 70-80% of people who test positive don’t have symptoms.
“That is quite a significant finding and one of the important things about this disease, in the same way that asymptomatic transmission is one of the things that makes controlling this disease really hard and is novel for any coronavirus, and is one of the things that makes it so difficult.”
Mr Hancock said the NHS test and trace scheme was part of the solution as isolating those who test positive for the virus would “break the chain of transmission”, particularly when they would not have otherwise known they were carrying the disease.
Baroness Dido Harding, who is heading up the NHS test-and-trace programme, said a rollout of antibody testing for the public would “come in time”, with health care staff currently being tested.
Antibodies being present in a blood sample are a sign that someone has contracted the virus in the past.
But Lady Harding said the issue was that not enough was known about what level of protection testing positive for coronavirus antibodies provided.
Earlier in the UK outbreak, there had initially been talk of immunity certificates being issued by the government to allow those who had previously contracted the virus to be exempt from some lockdown measures.
Lady Harding, speaking at the press briefing, said: “One of the challenges, and I know we all want it to be true that if we have antibodies it will then mean we are free to do things others are not, but at the moment… if we have an antibody test what it tells you is you have antibodies.
“Over time we would expect that we would build up the evidence to demonstrate what proportion or level of antibodies you need to actually have immunity and for how long you would have immunity.
“But at the moment, the science isn’t there.
“So I totally understand everyone’s desire to know if that cough or temperature they had in February or March was in fact coronavirus but at the moment it won’t tell you anything other than if you did or didn’t have it.
“It will come in time, and the testing we are doing, the antibody testing in health and care at the moment, is enabling us to build that scientific evidence base to the point at which then we will start to see the real benefit for all of us.”
The latest figures from the ONS study suggest that one in every 1,000 people currently have coronavirus, with 53,000 people thought to be carrying it in England at present.
Coronavirus: Everything you need to know