Accuracy of Flu Tests
How well can a given test tell if you have a disease?
Doctors call this measure “sensitivity.” The sensitivity of a test is expressed as a percentage. It means if we take 100 people who we know have the disease, and we test them, how many will come back positive? If the answer is 75, then we say the test is “75% sensitive.”
But medicine is notorious for tests that aren’t suuuuuuuuper great. Take mono, for example – the kissing disease. If your teen has a sore throat and fever, and it’s not strep, there’s a chance that it could be mono.
The problem is, the test known as “Monospot” is only 85% sensitive. So in the right clinical context, there’s still a 15% chance that your kid has mono even with a negative test.
For flu tests, the numbers have been even worse.
The flu test is usually a swab that goes in your nostril to the back of your nasal cavity (which is super uncomfortable). Then a test is run on the gunk that comes out to look for the flu virus.
The previous test that was commonly used was 70% sensitive. 70%! Kind of makes you wonder if the test is even necessary? Good clinicians would have told you it isn’t. If someone looks and sounds like they have the flu, then they typically have the flu.
And yet, a lot of people want the test.
Why? We like to having a result to point to, something on a piece of paper that says this is what we have. We don’t like the uncertainty of a doctor saying, well, they “probably” have this or that. And that’s an incredibly fair expectation.
Enter the new flu test. It’s 97% sensitive.
That’s right. It is vastly better. Which is good for when the test is really needed. The reality is that during a flu outbreak, an astute clinician can make the diagnosis on a clinical basis. When you’ve seen five people that day with high fever, body aches, runny nose and cough, then the sixth one with those symptoms has the flu. No test needed.
The CDC does however recommend testing in patients that may need to take antivirals (like Tamiflu). The very young, old, and immunocompromised fall into this category. And now, if you get the test, the result is a lot more reliable.
And hey, guess what? Remedy has the new flu test on hand, so we can easily administer and test in the comfort of your home or office.