Detecting COVID-19 Infection Increases With Frequent Testing

Testing every 3 days showed a test sensitivity of 98%.

A recent study conducted by investigators from the University of Illinois Urbana-Champaign, in collaboration with the University of Massachusetts Medical School and Johns Hopkins School of Medicine, has discovered that the chance of detecting the SARS-CoV-2 virus increases with more frequent testing.

Results from the study were published in the Journal of Infectious Diseases.

“This study shows that frequent testing can be really effective at catching COVID-19 infections and potentially blocking transmission," Christopher Brooke, lead author on the study said. "There are many places where vaccination is not yet widespread. With the rise of variants, testing remains an important tool for blocking the spread of the virus."

For the study, the team of investigators conducted 3 daily COVID-19 tests on 43 participants for 14 days. The 3 tests included a PCR nasal swab, a PCR saliva test, and an antigen nasal swab test.

The results of the tests were then compared to live cultures from a PCR nasal swab of an individual who was actively infectious.

Findings from the study showed that the PCR tests were the best at detecting cases before the individuals had an infectious viral load. This is very important so that they can isolate before they are able to spread the virus.

All 3 methods showed a 98% sensitivity in detecting an infection when they occurred every 3 days. When testing was reduced to 1 time per week, the sensitivity dropped to roughly 80%.

"If you are in a situation where you have the resources and capacity to do large-scale PCR testing with rapid results reporting like we did here at Illinois, you can identify infections early and potentially isolate people before they become contagious," Brooke said. "In places where PCR testing is not readily available or rapid results reporting is not possible, but the cheaper and more rapid tests are available, our data show how those tests can be deployed in a way that can increase their sensitivity - through repeated serial testing, ideally three times a week or more."