Throat Swabs Prevent COVID False Negatives

False-negative results are particularly problematic in containing the spread of COVID-19 — infected individuals can unwittingly transmit the virus while being completely asymptomatic. Why do false negatives happen? A recent study by Johns Hopkins researchers reported that timing may be an important factor; testing too early increased the chances of a false negative test. Here, the authors estimated that those tested for SARS-CoV-2 four days after infection were 67 percent more likely to test negative, even if they had the virus.

A study published in the Journal of Dental Research proposes a new method for reducing the occurrences of false negatives, simply by changing the sample source.

There are two main COVID-19 diagnostic tests, one that detects the presence of the SARS-CoV-2 virus, and the other that picks up antibodies, the body’s immune response to infection. The viral tests involve swabbing the inside of the nose and analyzing the sample for trace amounts of viral genetic material.

A study led by Jingzhi Ma at Wuhan’s Huazhong University of Science and Technology discovered that some patients who had negative results from their nasal swabs did in fact test positive from swabs of their oropharyngeal secretions (OS). Sampling the oropharynx, an anatomical region that includes the soft palate, throat, tonsils, and…