Covid: How does mass testing work?

Mass testing is coming to be seen as a key part of stopping the spread of Covid.

The hope is that it can identify people who may be contagious - including those without symptoms.

It's being deployed to help the lorry drivers stranded in Kent who need a negative test result to enter France.

Mass testing makes it easier to find people who may be unaware that they are infected.

They can then be told to isolate and be prevented from spreading the virus.

Mass testing can also be used in more targeted ways, including:

Pilot schemes have offered two types of testing, both involve swabbing the nose or throat.

The PCR (polymerase chain reaction) test is regarded as the "gold standard" by epidemiologists, but takes up to a day or longer to produce a result because the sample is sent off to a laboratory.

The lateral flow test involves a handheld kit that gives a result - a bit like a pregnancy test - in about 20 minutes. There's no need for a lab. Fluid from a nasal swab or saliva goes on one end, then a marking appears if you are positive.

Anyone who tests positive must immediately self-isolate for at least 10 days. Their contacts will be traced by NHS Test and Trace, and must isolate if told to do so.

Self-isolating means staying at home and not leaving even to buy food, medicines or other essentials, or for exercise.

People should order online groceries, or ask friends and family to get supplies and leave them outside the front door.

Anyone in England who fails to self-isolate after a positive test can be fined up to £10,000.

Anyone on low income who has been told to self-isolate in a phone call from NHS Test and Trace, can claim a £500 payment from their local authority.

Mass testing is being used to help clear long queues of lorries in Kent, after France shut its border to prevent the new coronavirus variant spreading.

Soldiers are working with NHS Test and Trace staff to give the lorry drivers lateral flow tests. They need proof of a negative test less than 72 hours before leaving for France, and will receive the result by text.

Communities Secretary Robert Jenrick said it is likely to take "a few days" to clear the backlog.

Testing will happen at "multiple" sites at Manston Airport, where more than 3,000 lorries are being held, and elsewhere.

Any who test positive will be offered Covid-secure hotel accommodation and must self-isolate.

Mass Covid testing of secondary school pupils in England is to be stepped up in January.

Staff will be offered a weekly test, and daily tests if they have had a case in their class.

Any pupil who has come into contact with a positive case will be offered daily tests for seven days. Previously, a whole bubble, class or year group might have been sent home.

Tests will be optional and require parental consent. Testing in primary schools could begin later in the term.

Children under 16 need to be accompanied by a parent or guardian to use a mobile testing unit.

Currently, most people can only have a test if they already have symptoms.

But under England's new, stricter tier system, the government would like mass testing to be widened out to areas with high rates of infection

This follows the success of a scheme in Liverpool, where everyone living or working in the city was offered a voluntary test.

Cases there fell from 635 per 100,000 people in mid-October to 99 by mid-December.

In addition to testing the general population, local authorities could also target high-risk workplaces and hard-to-reach communities.

This could be similar to the Liverpool pilot, which used mobile testing sites in care homes and schools.

People might be invited to have a test, but they can also book their own online. Whole families can also just turn up in their car.

NHS staff will also be tested for coronavirus twice a week. Routine testing of health workers already happens in the worst-hit areas.