One in 400 people in England has the Covid-19 virus, a survey of nearly 11,000 people in households suggests.
They were asked to carry out swab tests over the two weeks up to 10 May.
This indicates about 148,000 people in England could be currently infected – 0.27% of the population.
The figures could help ministers estimate the transmission rate of the virus, or R number, and whether tracking contacts of infected people is feasible or not.
The pilot study of 5,000 households gives a snapshot estimate of how many people could be infected with the virus at a given point in time, with or without symptoms.
It is set to expand over time to test 25,000 people for the virus in private households.
Households in all four UK nations will eventually be included.
The households tested in this survey did not include hospital patients or people living in care homes, where rates of Covid-19 are likely to be much higher, Office for National Statistics figures show.
Just 33 of the 11,000 people – in 30 households – tested positive in this snapshot survey.
Health or care workers in those households were several times more likely to be infected than workers in other sectors.