A: It’s a little more complicated.
Experts believe that the false negative rate (people who have a negative test result but are actually positive) can be around 30% with the swab test, generally due to improper sample collection. CT scans check for lung appearance, specifically ”ground glass” opacities, which are common to several diseases (pneumonia, for example). While there could be false positives (positive for COVID-19 but having something else), clinicians say that the chance of this decreases once out of flu season (during which the likely cause is pneumonia). In other words, it could be a more specific test.
Q2: So does that mean CT scans should be promoted to test COVID-19 patients?
A2: Certainly decreasing the false negative rate is important in clinical treatment of COVID-19. However, identifying cases at scale is as well. CT scans are a resource intensive method to test individuals. CT scans cost on the order of $200-$250 per scan and so are not economical at the scales required. Lower cost methods like contact tracing or expanding swab tests can work well if scaled.
*The bottom line: CT Scans may be beneficial for a subset of the population, but we should continue to focus on social distancing, contact tracing, and widespread low resource testing to aid in the control of COVID-19.
