Nasal swab followed by antibody test may catch incorrect Covid-19 diagnoses

Nasal swab followed by antibody test may catch incorrect Covid-19 diagnoses Use of dual testing could help as swabs miss around 30%-50% of infections, say UK researchers Sarah Boseley the Guardian

Testing people twice for the coronavirus, with a nasal swab followed by an antibody finger prick test, would catch most of those people who fail to get the right Covid-19 diagnosis, researchers believe.

Nose and throat swabs miss around 30% to 50% of infections, say the University of Cambridge team, as the virus can disappear from the upper respiratory tract into the lungs. But they say adding an antibody test can plug that gap. Antibodies show up from about six days after infection.

A team at Addenbrooke’s hospital in Cambridge has piloted the use of combined tests for patients arriving at the hospital. Many arrive with flu-like symptoms and need an accurate diagnosis to ensure they are put on the right wards, so that there is no risk of Covid-19 patients infecting others.

Ravi Gupta, professor of clinical microbiology at the Cambridge Institute of Therapeutic Immunology and Infectious Disease, said: “We still do not have a gold standard test for diagnosing Covid-19. This poses a challenge to healthcare workers, who need to make quick and safe decisions about how and where to treat patients.

“The two main types of test – PCR and antibody tests – both have limitations because of the nature of coronavirus infection and how our body responds. But we’ve shown that if you combine them and carry out both at point of care, their reliability can be hugely increased.” ...