Expired COVID-19 test kit? Here's what to do

Is it the flu, a cold or COVID-19? It's fall, and that means people are getting sick again.

Over the last three years, it's become a reflex for many to reach for that COVID-19 test at the first onslaught of sniffles.

So, what do you do if the expiration date on the box has passed?

Cardiologist Dr. Christopher Labos explains why you shouldn't stress too much about those numbers.

CTV News: Are the tests still good?

Labos: They probably are; the date may say it's expired, but they may not actually be.

Both Health Canada here in Canada and the FDA in the U.S. have pushed back the expiry dates on many home COVID-19 tests because when they were first put onto the market, there was a very conservative estimation of what their shelf life would be.

With additional data, it was shown that they do still function for at least two years post-manufacturing date.

The first thing to check is: has your test kit expired or not?

Most kits have not just an expiration date but a manufacturing date, so you can just add two years to that.

CTV News: Can we trust the results?

Labos: When you do the swab and have the viral antigen in your nose or the tongue, you put the Q-tip in the solution.

The reason it changes colour, the reason you get that second line to show that it's positive, is because you have an antibody latching onto the COVID-19 antigen and causing a colour change.

With time, those antibodies in the test kits can break down, especially if you don't store them properly: if you leave them in direct sunlight and they get very cold or very hot.

When these antibodies break down, you won't get that colour change, and you could, in theory, get a false negative.

If you get a positive result, it's probably true. It means the antibodies are still working.

The worry with an expired test is that it could give you a false negative, and you would think you're fine even though you're still sick and infectious, and you could then go out and infect other people.

CTV News: When is the best time to take a test?

Labos: With some of the newer variants, what we found, especially with the rapid tests, is they are not as sensitive as the PCR tests that were being widely used at the beginning of the pandemic.

When something is less sensitive, you can get a false negative.

If your test is positive, then you should assume that it's a true positive.

If your test is negative, it is a good idea to retest the next day or the day after that because a lot of people start negative and then become positive later.

CTV News: What do we do with the ones that have actually expired?

Labos: There's nothing inherently dangerous about most of these kits, but if there are any doubts, just call your local pharmacy.

They usually have ways of disposing of chemical waste like this, but again, there's nothing inherently dangerous about the test kits.