Debbie Parkes and her son Luke have been cautious to a fault throughout the pandemic. Before Christmas, Luke received negative results from two rapid “lateral flow” tests, leaving him comfortable about visiting his family home for the holidays.

But a week later, Ms Parkes and her 90-year-old mother were hospitalised after catching Covid-19 from Luke. “We followed all the rules, had done everything right and we ended up with the virus,” Ms Parkes said from her hospital bed.

The Parkes’ story is mirrored across England after lateral flow tests — which studies say pick up anywhere between 30 and 80 per cent of Covid-19 infections — gave false negatives.

The UK government has so far invested at least £1.5bn in lateral flow devices (LFDs) — with a further £912m out for tender. They are being used in secondary schools, care homes and hospitals, and this week ministers announced they would be offered to all 317 local authorities in England for mass community testing.

But critics of LFDs say ministers are throwing money at a flawed technology without publicly acknowledging its shortcomings, and some have called for their rollout to be paused.

Infographic describing various types of test for Coronavirus

“If you’re going to do something to everyone in the population we need to make sure that for goodness sake it works,” said Jon Deeks, professor of biostatistics at Birmingham university and an outspoken critic of the tests. “We do it for vaccines and we monitor all of the adverse reactions, why are we not doing it for tests?”

“The government doesn’t want to acknowledge the harms in case people don’t use them but we have to be honest and truthful with people so that they can make informed decisions,” he added.

Unlike PCR tests, which look for Covid-19’s genetic material, lateral flow tests identify a protein antigen on the virus’s surface. Because they do not amplify the virus they struggle to detect lower levels of infection.

The bulk of the UK government’s spending on lateral flow tests has so far gone to a US company called Innova, which has received £1bn in contracts to procure hundreds of millions of LFDs made in the Fujian province of China.

The company was set up in March by a Hong Kong and LA-based investment group called Pasaca Capital. Distribution of the devices in the UK has been led by a company called Disruptive Nanotechnology, which has no fixed assets and debts of £3,600. Its directors, Kim Thonger and Charles Palmer, previously worked in shoe sales and property, and do not have a background in health.

The Innova tests have been through dozens of trials in the UK, both in laboratories and in the community. Mass screening in Liverpool — the biggest pilot to date — found they picked up only 40 per cent of positive cases, although the proportion rose to 70 per cent for those with a high viral load, who are believed to be most infectious.

Innova did not immediately respond to a request for comment.

The Department of Health and Social Care defended the use of lateral flow tests and said the devices were given a “rigorous evaluation by the country’s leading scientists”.

“14,800 Covid-19 carriers have already been detected using LFDs who would have otherwise not been identified. These individuals have subsequently been told to self-isolate, therefore preventing the onward transmission of the disease,” it said.

When the UK’s health watchdog, the Medicines and Healthcare products Regulatory Agency, authorised LFDs for “self testing” in the community late last month, it wanted to make clear that they should be used to “find” cases of Covid-19 infections among people who were not aware they had the virus, rather than to “enable” people to undertake risky behaviour.

However, this was not made clear to the public by the MHRA and critics argue that official messaging on the effectiveness of LFDs has been inconsistent. For example, a previous version of the Government’s Handbook for schools, which have received millions of the tests, stated that they are “as accurate in identifying a case as a PCR test” — a claim that was later dropped.

This week the government announced it was buying tests from a Derby-based company called SureScreen, the first UK-produced test in the government’s lateral flow arsenal. Unlike Innova, the company has been working in diagnostics for 25 years.

Encouragingly, the SureScreen’s internal clinical studies found its LFD picks up 96.2 per cent of active infections compared with PCR tests, and Public Health England has found it picks up 97 per cent of cases with a “high viral load”.

If confirmed in the wider community, the results mean the LFDs would be a valuable element in the testing programme, although the government has bought only 2m kits, at a cost of £6m, so they will form a tiny proportion of the total number being rolled out around the country.

“There’s a very wide variation of quality on the market so you can’t consider that all lateral flow devices are the same,” said David Campbell, director of SureScreen.

“The messaging is really important so people understand where these tests should be used,” he added.

Given the accuracy of tests currently being deployed, many are calling for the wider rollout of Innova LFDs to be paused until its reliability is more clearly communicated.

“These tests are not sensitive enough to pick up truly positive cases so a negative test should not be relied on for reassurance,” said Saroja Vernon, a GP in Stockport.

Dr Vernon is currently suffering from Covid-19 after her ex-husband — also a doctor — spent the weekend with their children following a negative lateral flow test result.

“If they’re weeding out some of the cases, that’s positive, but with such a patient-facing workforce like ours, is that good enough? I don’t think it is.”