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DENVER (KDVR) — As free COVID rapid tests from the federal government start arriving in Coloradans’ mailboxes, many are wondering how well they actually work.

Even researchers say there’s no guarantee you’ll get an accurate result.

Now, don’t go thinking, “What’s the point in using them then?” because they are indeed one of the best tools you and your family have when it comes to detecting COVID.

According to experts over at HealthOne in Denver, if you get a positive result with an at-home rapid test, you can pretty well be reassured 99% of the time that it’s a true positive test.

However, if you get a negative test result, the accuracy is only in the 60% to 70% range, meaning you may have a 30% to 40% chance of it being a false-negative test.

So what should you do?

Experts say if you’re really concerned about having acute COVID, you might want to take another rapid test in a day or two.

“The challenge with this virus is that you can have it acutely without having any symptoms, so there’s period of maybe two to three days before you develop symptoms and two to three after where your test may be more positive. So if you take it too early, maybe before you start developing symptoms, you may not have a viral load that’s able to be detected. So rechecking in a day or two if you’re really concerned might be very valuable,” explained Dr. Scott Joy, chief medical officer for HealthOne Physician Services Group.

According to Joy, if you’re still not convinced, you might want to go for a more specific PCR test, which is considered the gold standard.

Joy explained PCR tests tend to detect the virus in your nose — which can last for several weeks.

In this case, rapid tests are considered a better marker for contagiousness.

In terms of how you should use your at-home rapid test, the advice being given by the Food and Drug Administration is to only swab your nose.

Many people have been swabbing their throats first and then their nose after, as some experts suggested it would provide more accurate results.

Denver-based doctors don’t endorse that method.

“I do not recommend beyond what is recommended, just because that keeps it true to the scientific principles that have been validated,” Joy said.

It’s still unclear how long a person can be infected with COVID, but according to Joy, the most infectious period is two to three days before symptoms and two to three days after.

Research shows saliva tests pick up COVID 100% of the time, compared to nasal swabs, which typically detect 86% of confirmed cases.