Clive Cookson and Laura Hughes
The Office for National Statistics said on Wednesday the initial boost to the sample size from the current level of 28,000 would be in place by October but it planned eventually to involve 400,000 people in England. The statistical agency, which runs the survey with Oxford university, will also extend the project to Scotland, Wales and Northern Ireland.
So far, the ONS survey has been too small to give strong statistical confidence in its findings, beyond a general trend downward in infections from April to June, followed by a slight increase during July and a levelling off so far in August.
Last week the agency said the number of people who had the virus in England was in a range of 19,000 to 40,700 with 95 per cent confidence. This estimate was based on just 58 people in the ONS sample testing positive for the virus over the previous six weeks.
The survey is designed to establish community infection levels, outside care homes and hospitals, and the ONS said the expansion would enable it to make far more accurate estimates, particularly at local level when flare-ups occur.
“Vigilance is key to containing this pandemic and the extra data on the spread of infections and antibodies at local level will be invaluable to the planning of effective local responses,” said Ian Diamond, the UK’s national statistician.
Letters are being sent to tens of thousands of households inviting their participation, with north-west England a particular regional priority. “If you’ve been approached to take part then please do so,” Sir Ian said. “You will be helping us all to contain this terrible virus and get on with our lives.”
Participants provide samples from self-administered nose and throat swabs and answer a few short questions during a home visit by a health worker. The swab tests show whether or not people have the virus.
In addition, 20 per cent of participants aged 16 and over provide a blood sample. These tests help determine what proportion of the population has developed antibodies to the virus. Participants will be asked to give further blood monthly for the next year.
If the survey carries on for two years at the planned scale, it will cost around £750m, said Katherine Kent, ONS lead analyst. But the study will be assessed periodically and will be discontinued if it is found no longer to be useful.
Separately, Matt Hancock, health secretary, pledged to introduce population-wide mass testing as lockdown restrictions continue to be eased across England. The ONS survey is independent of the mass testing programme.
“This is a really, really important drive that we have across government to bring in mass testing, population-wide testing,” Mr Hancock told BBC Radio 4’s Today programme.
He said ministers were working “as fast as we can” with dozens of homegrown and international companies to get the “very best” testing capacity.
Declining to put a date on when the pledge would be fulfilled, he said:
“We'll ramp it up, certainly over the remainder of this year. I'm not going to put a firm deadline on it.
“This moonshot to have testing ubiquitous and available to reopen all sorts of things to reduce the burden of the quarantine arrangements, which nobody wants to have in place, to allow us to reopen parts of the economy, that is an incredibly important project within government right now.”
The government has previously promised to expand testing capacity to 500,000 a day by October in an attempt to keep a lid on the disease and avoid a return to tougher lockdown measures. According to the latest government data, just over 150,000 tests were carried out in the UK on Tuesday.