Cold weather, other factors may affect at-home COVID test results

LINCOLN, Neb. (KLKN) – Free at-home COVID tests from the government are starting to arrive in mailboxes across the capital city, but frigid temperatures and other factors could compromise their accuracy.

Antigen tests exposed for extended periods of time to temperatures below 36 degrees can deliver inaccurate results, according to a study published by the National Institute of Health.

“When they’re at lower than specified temperatures they tend to misread a little bit, so they lack what specificity and they tend to create some false positives,” Dr. Mark Rupp, a Professor and Chief of Infectious Diseases at Nebraska Medical Center said.

There is liquid inside of the cartridge that can freeze and if that happens, the accuracy of your results immediately decreases.

“What you also want to avoid are these kits going through multiple freezes, thaw cycles. They do contain a little container or buffer solution, and if that buffer solution goes through multiple freezes and thaws it probably starts to really impact the way it performs,” Dr. Rupp said.

If the test is outside in chilly temperatures for an hour or two, it’s most likely fine as long as you bring it indoors and let the test get to room temperature before using. But if your COVID tests spent the night outside in the mailbox, doctors say it’s best to order more or use a PCR test instead.

“If they’ve been sitting out on your porch for several days, waiting for you to come home, that’s probably not going to perform quite as well as we’d like,” Dr. Rupp said.

Other factors can also affect the accuracy of your COVID test such as the specimen that’s obtained. Experts say it’s important to follow the instructions very carefully.

“They do tell you how to gather the specimen from your nostril and it’s important you do that and try to do it correctly, so that’s one of the variables that are inherent in people performing their own tests,” Dr. Rupp said.

The state is looking at doing proctored testing, where you go online and someone walks you through the performance of the test in order to get accurate results, but also so those results are transmitted into the state’s database.