If unvaccinated people stay together in a poorly ventilated room for a long period of time, their cotton swabs might become entangled, meaning that their tests will always show the same outcome.

Panel 1:
G and H are at their usual table, doing a COVID-19 rapid test.
H: I wonder how long we’ll have to keep doing these COVID-19 tests.
G: looking at their test Oh, gosh dang it.
Panel 2:
H: What? Don’t tell me its positive!
G: No, don’t worry. But I forgot to observe which nostril I put the swab in and now it’s doing this ...
Panel 3:
Instead of the usual bars, the test shows a double slit interference pattern.