Re: expired Covid test kits and false positives

[intrepidity]

Can anyone explain how or why an expired test kit might produce a false positive?

My opinion is that it won't, or shouldn't. A false negative, sure. But how would it produce a false positive?

I finally got sick after 5 years of not having one single cold or flu. I only had all the old covid test kits that I got via USPS, all of which had "expired" by at least a year. (Disclaimer: expiry dates on everything are very squishy to me so I usually take them with huge grains of salt.) So, I used a couple of the "expired" kits, one was the oldest and one the newest, and both showed a positive result. I did not think at the time to do a negative control (like maybe swab my dog's mouth?) but I did have my son and benefactor, who so graciously donated the virus to me, take the same tests, and his were also positive (surprise!!) but, since he was several days ahead of me symptom-wise, his test signal was noticibly fainter, which confirmed to me the validity of the tests.

A long way to say: don't discard those old "expired" kits, because they still may be useful.

But, if anyone can answer the original question. i'd appreciate it.