The UK’s healthcare regulator has expressed concern to the government that its multibillion-pound mass testing programme is “a stretch” of the authorised use of rapid tests, the Guardian has learned.
The Medicines and Healthcare products Regulatory Agency (MHRA) has approved the lateral flow devices to be used to find coronavirus cases but not to act as a “green light” for people who test negative to enjoy greater freedoms.
The regulator is concerned that people who test negative will be given false reassurance by their result and will let down their guard if they believe they are Covid-free.
There is very little data to show how well the Innova lateral flow devices detect the virus when used as a self-test by someone who has no symptoms. They are being used by millions of people a week in England under the government’s universal testing programme.
Senior government officials have raised “urgent” concerns about the mass expansion of rapid coronavirus testing, estimating that as few as 2% to 10% of positive results may be accurate in places with low Covid rates, such as London.
…However, leaked emails seen by the Guardian show that senior officials are now considering scaling back the widespread testing of people without symptoms, due to a growing number of false positives.
…On 9 April, the day everyone in England was able to order twice-weekly lateral flow device (LFD) tests, Dyson wrote: “As of today, someone who gets a positive LFD result in (say) London has at best a 25% chance of it being a true positive, but if it is a self-reported test potentially as low as 10% (on an optimistic assumption about specificity) or as low as 2% (on a more pessimistic assumption).”
Rob Verkerk, Founder, Executive and Scientific Director of the Alliance for Natural Health International, a scientist who has for 30 years been exploring positive ways to span the gulfs between science and the law, between academia and industry, and between governments and their people.
We identified virtually no evidence for mass screening of asymptomatic individuals using rapid antigen tests in people with no known exposure. A small study screening travellers returning from high‐risk countries (Cerutti 2020), identified only five SARS‐CoV‐2 infections (prevalence of 3%) with a reported sensitivity of antigen testing for detecting infection of 40%. However, important larger studies have been published since the end of our search, as mentioned above.
Most people infected with SARS-CoV-2 are contagious for 4–8 days.7 Specimens are generally not found to contain culture-positive (potentially contagious) virus beyond day 9 after the onset of symptoms, with most transmission occurring before day 5. This timing fits with the observed patterns of virus transmission (usually 2 days before to 5 days after symptom onset), which led public health agencies to recommend a 10-day isolation period. The short window of transmissibility contrasts with a median 22–33 days of PCR positivity (longer with severe infections and somewhat shorter among asymptomatic individuals). This suggests that 50–75% of the time an individual is PCR positive, they are likely to be post-infectious.
Immunocompetent staff, patients and residents who have tested positive for SARS-CoV-2 by PCR should be exempt from routine re-testing by PCR or LFD antigen tests (for example, repeated whole setting screening or screening prior to hospital discharge) within a period of 90 days from their initial illness onset or test (if asymptomatic) unless they develop new COVID-19 symptoms. This is because fragments of inactive virus can be persistently detected by PCR in respiratory tract samples following infection – long after a person has completed their isolation period and is no longer infectious.