Last week first minister Nicola Sturgeon said the Scottish government hoped to have “a more widespread” Covid testing approach in schools when schools return, as she announced that most pupils would remain away from school buildings until at least the middle of February.

It is not the first time a mass coronavirus testing regime for Scottish schools has been alluded to - in the previous week, on Wednesday 13 January, education secretary John Swinney said the government would ensure “all appropriate mitigations” were in place “to support a safe return [to school]”.

He said that included “exploring the role enhanced testing of school staff could play” and that two pilots of different models were due to get underway.

So, as England’s education secretary, Gavin Williamson, tells English schools to test staff twice a week, what stage are Scotland’s plans at?

Coronavirus: Why carry out mass testing in schools?

Mass testing makes it easier to find people who may be unaware that they are infected with Covid-19, which means they can be told to isolate and therefore be prevented from spreading the virus.

It is estimated that individuals with the coronavirus who do not have symptoms make up around a third of all cases.

Background: John Swinney announcement

In England: Schools told to test teachers for Covid twice a week

Opinion: ‘Those boxes of lateral flow tests are staring at me’

What are the two approaches to Covid testing in schools that the Scottish government is trialling?

The government is piloting two different models - one using in-school testing with lateral flow devices, and another involving at-home testing using PCR (polymerase chain reaction) tests.

Lateral flow tests bring quicker results than standard PCR tests and are similar to at-home pregnancy tests, with the results revealed as a line in about 30 minutes, following a swab of the nose and throat.

Lateral flow tests have been criticised for being inaccurate but they deliver results quickly, and scientists argue they are an essential tool in the current pandemic.

PCR tests also rely on swabs but they go to a lab, rather than the results being revealed on-site.

The PCR tests are better at finding very small amounts of the virus.

When did the pilots start and how long will they last?

The pilots started last week and are expected to last for four weeks.

Where are they taking place?

The lateral flow testing pilot is being carried out in two secondary schools in two local authorities: Midlothian and South Ayrshire. These will be offered to all students currently attending school and to staff. Testing will be done entirely on a voluntary basis, with parental consent where appropriate.

Those who volunteer will do the tests in school under supervision by trained staff on a weekly basis. In the event of a positive test, a PCR test will be carried out. That can be done in school or with a test kit at home. The national guidance on self-isolation must be followed.

The PCR tests will be offered to staff at eight schools - six secondaries and two primaries - in five local authority areas: West Lothian, South Lanarkshire, North Lanarkshire, Stirling and Clackmannanshire, subject to the current exceptional school-opening arrangements allowing continued participation.

These tests will be done once a week at home and, again, testing will be done on a voluntary basis.

What does the government hope to learn?

It says the pilots are primarily intended to help “rapidly identify and understand any logistical and implementation challenges involved in the different models of testing”.

A spokesperson added: “Consideration of options to scale up testing as part of efforts to mitigate Covid risks is ongoing, and will be informed by any early learning from these pilots. We have been working closely with local authorities and schools to ensure these pilots run successfully and provide as much learning as possible. Regular staff testing is just one potential mitigation that may help schools in addition to the robust package of measures already in place.”

How does this compare to the testing regime underway in England?

The Department for Education (DfE) threw secondary schools into turmoil before the Christmas holidays by announcing a national plan for them to carry out Covid-19 tests of their own staff and students when schools returned in the week beginning 4 January.

This included the goal of keeping close contacts of Covid cases in school by giving them seven daily tests. If they remained negative, the idea was self-isolation would not be necessary and attendance at school could continue.

Of course, the UK government’s testing plans were never put into action fully as a result of the majority of pupils being told to stay at home, and now the plan to use lateral flow tests on people who have been in contact with a confirmed case of the virus has been paused in schools.

Testing using lateral flow devices in English secondaries is continuing. The government says staff should be tested twice a week and under the current rules pupils returning to school should be tested twice, as has been the case since some pupils returned to school.

The general secretary of English heads’ union the Association of School and College Leaders, Geoff Barton, said he supported using the tests for mass testing because the process “should pick up at least a proportion of asymptomatic cases and improve safety”. He said he was relieved the tests had been paused as an alternative to self-isolation because “they don’t detect all those with the infection”.