Cold weather may affect accuracy of rapid tests shipped to homes, experts say

Many rapid at-home COVID-19 testing kits recommend storing the tests above 35 degrees. That could spell trouble as winter storms affecting millions of Americans this week collide with the delivery of some of the free government-supplied rapid tests people are expecting, USA Today reported Feb. 4. 

Experts told the news outlet that if the liquid reagent inside the cartridge that comes with most at-home tests freezes, the tests' accuracy diminishes.

How long a test kit has been left in the cold may correlate with how much its accuracy is affected, Geoffrey Baird, MD, PhD, chair of laboratory medicine and pathology at the University of Washington School of Medicine in Seattle told the news outlet. 

"Just as anything with liquid, if it's chilled or frozen, it changes. That's the same with these at-home tests," Dr. Baird said. "At a time where temperatures are freezing in most places, it's safer to choose another test."

If a testing kit was outside for a couple of hours, its accuracy may be slightly lower. If it's left overnight in 25-degree weather however, it's best to order a new test or seek a polymerase chain reaction test, Dr. Baird said. 

Studies have suggested when at-home tests are subjected to significant temperature shifts, false-negative rather than false-positive results are more common, Dr. Baird said, adding that if someone tests negative with an at-home test after an exposure, they should receive a PCR test to confirm. 

The government in January launched its website for Americans to request free rapid test kits be shipped to their homes. So far, about 1 billion tests have been ordered for distribution via the U.S. Postal Service, USA Today reports.


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