Cold weather may create inaccuracies in COVID-19 antigen test results, study finds

As of Jan. 19, any U.S. resident can order a testing kit through the United States Postal Service using their home address. Credit: Dominick Sokotoff/ZUMA Press Wire via TNS

Due to cold temperatures, COVID-19 antigen tests may not yield accurate results if left outside for too long, according to a study in the Journal of Clinical Virology.

Still, Ohio State experts say the antigen tests are useful tools, if stored properly. The findings about temperature’s effect on the tests comes as the U.S. Postal Service continues to ship free rapid COVID-19 antigen tests to U.S. residents who place an order online. 

On- and off- campus students can order the rapid antigen tests to their residences.

Preeti Pancholi, director of clinical microbiology at the College of Medicine, said the liquid in the test is susceptible to freezing, producing an unclear or incorrect result. She said there are certain indicators a person can look for to determine if a test is unusable.

“In some cases, the solution may look cloudy if it’s compromised by temperature,” Pancholi said.

Pancholi said some rapid antigen tests must be at room temperature for 30 minutes before being used. She said if the test was left overnight in weather below 25 degrees Fahrenheit, she recommends getting a new test, if possible.

Barring any temperature-related defects, antigen tests still serve as a viable testing method.

Jeff Van Fossen, ambulatory service lab manager at the Wexner Medical Center at Ohio State, said in an email the antigen tests are convenient but less sensitive than PCR tests, which can pick up on lower amounts of virus in the body.

“Antigen test will work well with patients that have a high viral load,” Van Fossen said. “Those without a high viral load can be missed by the antigen test.”

Van Fossen said if a person is symptomatic, an antigen test will typically work well. Asymptomatic individuals may not receive reliable results due to having a lower viral load.

For more information about COVID-19 testing, visit the Centers for Disease Control and Prevention website.