According to data released last week by the Office for National (ONS), 71% of people tested positive for coronavirus had no symptoms.
But during the daily government briefing, Hancock suggested that the number of asymptomatic cases may be higher.
The health secretary said, “The overall answer is that yes, there are people who do not have symptoms but who have the virus.
“And in fact, in the ONS study, we find that about 70-80% of people who test positive have no symptoms.
“This is a fairly important discovery 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 difficult and is new to any coronavirus , and is one of the things that makes it so difficult. ”
About 20,000 households have been invited to participate in the ONS study and so far, almost half of the households have provided at least one swab for testing.
There has been much debate about the contribution of asymptomatic people to COVID-19 in the spread of the virus.
A World Health Organization (WHO) scientist said on Monday that it was “very rare” for people with no symptoms to transmit the disease, but then pointed out that it was based on a set of studies relatively small.
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Dr. Maria Van Kerkhove said that this evidence came from countries that had carried out “detailed contact tracking”.
WHO officials said on Tuesday that there are “many unknowns” regarding asymptomatic transmission.
Hancock said the ONS results underscored the importance for people to comply with self-isolation as part of the test and trace program, even if they don’t have symptoms.
“They are isolated while they are infectious, which breaks the chain,” he said.
“That’s why 14-day isolation is so important to stopping the spread of the virus. ”
He also told the public that it was his “civic duty” to comply with the program.
“The test and the trace are our radar. You have your role to play, ”he said.
Another 151 people in the UK have died after being tested positive for the coronavirus, according to figures from the Department of Health released on Thursday.
This brings the total number of deaths in the UK to 41,279.