Rapid antigen tests may eventually be given the go-ahead, even on a limited basis, to find out if primary school children have Covid-19. It would mark the ultimate victory for the many who have been advocating their wider use for much of the pandemic.
he arguments against these tests are now well rehearsed. They are not as accurate as the gold-standard PCR test, and a false negative could mean someone is less likely to take Covid-19 precautions.
Supporters of antigen tests say they are one useful tool, among other measures, to reduce the risk of someone who has the virus and is infectious going to the workplace or socialising and transmitting it to others.
If they are used in schools, how would it work and what do we know of the results of pilots in childcare and other facilities?
Tánaiste Leo Varadkar has revealed they may yet be used in schools among children who have no symptoms, but were in close contact with another pupil who tested positive for Covid-19.
The likelihood is that much the same system introduced by the HSE for fully vaccinated close contacts without symptoms would apply to children.
They would get a pack of tests from the HSE and their parents would do the test at home three times every second day. The result is available in 15 to 30 minutes.
If there is a positive result, the child should stay home from school and get a PCR test. It is seen as one way of finding children aged five to 12 who are positive.
Weighing up benefits
The benefit of using antigen tests is that they may pick up some children who are Covid-19 positive. These children may have no symptoms, and without the antigen tests may unwittingly pass on the virus in school, at home or at play.
The tests also mean that children who are close contacts will not automatically lose 10 days schooling, as was the case under the old system, which was dropped in late September.
But while there is nothing easy when it comes to staying safe in the pandemic, there are some lessons that need to be taken on board if they are used.
Instruction is recommended on how to insert a swab in the child’s nostrils in order to get a good sample for testing. A useful video is on the HSE website. Parents may have to contend with a reluctant child.
Antigen tests are not as accurate as a PCR test but if done when a person is most infectious, they could be around 80pc reliable.
They perform best in symptomatic people around three to five days after exposure to the virus. But the children tested in Irish primary schools would only be those without symptoms. Those with symptoms need a PCR test.
There is some good insight into pilot tests involving antigen tests in childcare facilities, nursing homes and colleges by the HSE. All those who had a positive antigen test in childcare and colleges went on to have the result confirmed as correct with a PCR test.
Up to last week, 3,500 results in nursing homes were reported, with two positives. The tests were carried out on staff in nursing homes. At that point, no outbreaks occurred in the facilities involved.
Feedback included praise for ease of use, and the swabs were “much less unpleasant” than nasopharyngeal swabbing. Participation rates varied from 100pc to as low as 15-20pc.
One of the downsides is the administrative burden in signing up people, distributing test kits and following up with reminders to continue to test and report results online to the HSE.