A British scientist has said that flawed PCR tests mistook common colds and flu for COVID-19 and should have been axed.
”Many people may not have been infectious, despite getting a positive test,” professor Francois Balloux, director of University College London’s Genetics Institute, told The Mail on Sunday.
”There appears to have been little or no oversight of these new labs, and with different PCR methods and equipment being used,” says Prof McNally.
UK Health Security Agency (UKHSA) had suspended a COVID-19 testing laboratory in central England over concern that it has been incorrectly giving negative PCR test results to people who are infected.
NHS Test and Trace launched an investigation into a lab in Wolverhampton after reports of people getting negative PCR test results after testing positive on rapid lateral flow devices (LFDs).
PCR testing for SARS-CoV-2 is far from 100% sensitive
While it is acknowledged that PCR testing is exquisitely specific (there are very few false positives, and when they occur it’s usually do to contamination of the sample), and it is exquisitely sensitive when there is viral RNA on the swab, we also know that in the real world, many patients who have genuine Covid-19 disease (based on subsequent confirmation and/or classic constellation of typical signs and symptoms) test negative on PCR testing of swabs. Even in hospital – it is not entirely down to poor technique when performed eg by the patients or poorly-trained volunteers at test centres.
Sensitivity of PCR testing in the real world (taking into consideration the likelihood of the virus getting onto the swab) is only of the order of 70%. It misses (gives false negative results) in about 30% of people who do actually have the virus, and who may be contagious.
So, comparing, say, lateral flow or LAMP tests with PCR, assuming that a negative PCR test means the other test is definitely a true negative, fails to take into consideration the false negative rate of PCR tests, rendering them even less useful.
Who should get tested for COVID-19?
Your healthcare provider may recommend testing for COVID-19 if you have any of the following symptoms:
- Fever or chills.
- Shortness of breath or difficulty breathing.
- Muscle or body aches.
- New loss of taste or smell.
- Sore throat.
- Congestion or runny nose.
- Nausea or vomiting.
Not everyone with COVID-19 develops symptoms. And not all symptomatic people develop all of the symptoms listed above. Please check with your healthcare provider if you’re feeling unwell during the COVID-19 pandemic — even if you’ve been vaccinated.