Public health chiefs in Hertfordshire are gearing-up to test almost 5,000 people a week for Covid – even though they don't have symptoms.

The 'rapid' tests will be aimed at key and essential workers – such as transport workers, supermarket staff and public sector employees – who cannot work from home.

And they will be delivered at a series of fixed and pop-up sites across the county – as well as buses, that will be available to visit specific areas or workplaces.

The roll-out of the tests began this week with limited tests available in Potters Bar and Cheshunt and in Watford and Three Rivers – with almost four per cent of people testing positive, without symptoms.

Of the 350 people who took the test in Potters Bar/Cheshunt, there were 14 – that's four per cent – who tested positive for Covid-19.

And in the Watford/Three Rivers location, 18 of the 492 residents tested – that's 3.6 per cent – were found to be unknowingly positive for Covid-19.

If the results were the same across the county that could mean there are 44,000 people who unknowingly have Covid-19 – and could be spreading it to others.

But if those 32 people identified by the this week's testing now self-isolate, as required, that could be enough to reduce the number of future cases in the county by hundreds.

Speaking at a media briefing on Friday (January 22), director of public health Jim McManus stressed that the impact of the testing would be linked to the numbers willing to self-isolate, if required.

". . . The quicker we get those positive people to self isolate the faster we will stop the curve – and actually tip the curve to go down," he said.

"It will have a positive impact if we pick them up but then they self isolate. That's the crucial thing. All the testing in the world won't make a blind bit of difference if people aren't self isolating."

The roll-out of 'community' testing – which uses lateral flow tests – is part of a national testing programme.

And Mr McManus says the approach in Hertfordshire – mixing fixed sites, pop-up sites and roaming buses – is designed to offer flexibility.

By operating sites in each 'quadrant' of the county the aim is to provide as much geographical equity as possible, but still to offer flexibility should there be areas with larger outbreaks.

Mr McManus acknowledged self-testing would be an alternative, but he says the accuracy of tests is greater if administered – with just four of the 800 tests 'void' this week.

The 'rapid' testing is in addition to the asymptomatic testing that is already available to NHS workers and care home staff.

And it is in addition to the drive-through testing sites for residents who have symptoms, including a persistent cough, temperature or change in sense of taste.

Commenting on the rollout of the rapid testing following the media briefing, the county council's cabinet member for public health and prevention Cllr Tim Hutchings said: "Around one in three people who have coronavirus have no symptoms, which means they can spread the virus to their loved ones without realising.

"By taking a rapid test, it means you will know almost immediately if you have coronavirus, so that you can protect your family, friends and community and ultimately break the chain of transmission of the virus