If you’ve ever wondered when is the best time to test for COVID-19 before you head out for your next social event, a team of researchers from the Yale School of Public Health and Yale University may have the answer.
In a study published July 27 in the International Journal of Public Health, the researchers explored how well rapid antigen and RT-PCR COVID-19 tests prevented transmission of the virus following someone’s arrival at an event, based on the time they were tested before leaving.
The team developed formulas to calculate “post-arrival transmission” in two different scenarios:
- When no test is done
- When someone is tested via RT-PCR or by 18 commercially-available rapid antigen tests at various times before arriving at an event
They found that doing a rapid antigen test as close to departure time as possible can reduce COVID-19 transmission by as much as 46.7 percent, depending on the test used, while doing an RT-PCR test 12 hours before arrival reduced virus transmission by 31.1 percent. Based on these results, the researchers conclude that testing via rapid antigen tests as close to leaving for an event as possible is best to reduce virus transmission.
“Testing closer to arrival—ideally on the day of arrival—is more effective at reducing post-arrival transmission than testing earlier,” the researchers state in their study abstract. “Rapid antigen tests perform the best in this application due to their short turnaround time.”