Lateral flow tests were given to children with out of date guidance according to a report.
The Telegraph says an investigation has been launched after the Covid-19 tests handed out this month came with incorrect instructions.
The kits were accompanied by a Government leaflet which said they are for use if you have symptoms or are asymptomatic, but a second leaflet in the box said the kits are for people "suspected of Covid-19 by their healthcare provider”.
Lateral flow tests which provide results in 30 minutes are for those who do not show symptoms, Government guidance states. Anybody with symptoms should take a PCR test and self-isolate, as PCR test results are more accurate and are reported automatically. This has led to concerns that pupils who have Covid-19 are taking lateral flow tests and getting negative results.
The Medicines and Healthcare products Regulatory Agency (MHRA) is now investigating, reports Mirror Online.
School pupils are required to take lateral flow tests twice a week if they are asymptomatic.
Professor Allyson Pollock, a public health expert at Newcastle University, told The Telegraph : "The whole mass testing programme is confusing, chaotic and the antithesis of good public health practice.
“If you do mass testing you need to do proper evaluation beforehand, which would identify problems like this.
“Lateral flow testing should have gone through the UK National Screening Committee for proper evaluation.”
The government spent £1.3 billion on up to 384 million lateral flow testing kits and most of them were made by US firm Innova Group, according to the British Medical Journal.
Public Health England research found the Innova tests were successfully detected cases of Covid-19 in 79.2 per cent of cases, when used by trained laboratory scientists.
But they were only 57.5 per cent effective when used by track and trace centre staff employed by Boots.
A Downing Street spokesman said lateral flow tests had been “rigorously evaluated".
He added: "We believe they are both accurate and incredibly useful in terms of being able to spot asymptomatic cases of the virus”.