CHARLESTON, W.Va. (WCHS) — Similarly to the COVID vaccines, rapid virus testing kits need to be stored at the right temperature to provide accurate results.

With a shelf life anywhere from one to two years, you can keep those at-home COVID testing kits for a while, but keeping them at the right temperature is key.

“Every one of them that’s approved by the FDA has that temperature grading 36 degrees to 86,” Dr. Sherri Young, health officer for the Kanawha-Charleston Health Department, said.

Young said the accuracy of an at-home test could become compromised if the testing liquid, or reagent, is affected by freezing temperatures.

“If it sits too long in a mailbox, and its frozen, it’s been very cold for a couple of days, it can freeze the reagent,” she said. “What will happen is it can inactivate some of the enzymes, and then if it freezes, thaws, then freezes again, it can even turn into a powdery substance. So, they’re very temperature sensitive.”

It’s best to store the testing kits in a dry, room-temperature area, away from sunlight. Justin Simons, chief executive officer and founder of My Labs Direct, said a recent cold snap in his native Dallas, Texas, affected the results of rapid tests at a testing event.

“We were in the 20s temperature range, and we were seeing inconclusives coming back right away on the first couple tests,” Simons said. “No line was showing up on the indicator strip. So, we realized this could be problematic. We obviously threw those samples away, got everything heated up back at ambient temperature, and then started to see reaction.”

When used appropriately, Young said, at-home COVID testing kits can be more than 90% accurate.

“The problem with the home tests is that sometimes people take them too early,” Young said. “So, if you’ve just had an exposure a day or two before, you still need to wait until the day three, four or five to get tested just to be on the safe side.”

Young said it’s a good idea if you’ve tested positive at home to come into the health department to get a confirmatory test, so that if you are positive, you can be logged into the state’s COVID tracking system.