Positive home rapid but negative PCR. Can someone explain?

[matrips]

I’m trying to figure out how each test works and how this can happen.  I know the PCR is the gold standard and looks for genetic material of covid.  What is the rapid test looking at?  And why would that give a positive?  It was a Binax test I administered, so I know all directions were followed.  We’ve used them in the past and always gotten negatives. This time though, the positive result came quickly and strongly, on the first day of symptoms.  But then the PCR, taken 2 days later, was negative.

[YaelAldrich]

Was this a vaccinated person? My theory is that they did have the virus in their nose; enough to trip the BinaxNow. But the person's vaccinated immune system fought off the virus to the point after two days there wasn't anything left to catch by PCR.

Could be insanity but when I've heard this this is how my knowledge plays itself out.

[Spryte]

Friend’s father in Germany has had two positive RATs and a negative PCR. He’s vaccinated, and they decided he fought it off.

[matrips]

It was an unvaxxed person. 

[KSera]

Did they repeat either test? I would think a false negative on the PCR, though it's strange that it would read negative when it is a more sensitive test. PCR poorly performed?? Were both nasal?

[matrips]

Both were nasal.  

[YaelAldrich]

17 minutes ago, matrips said:

It was an unvaxxed person. 

I still stand by my hypothesis (although less than before). This person probably got Covid before and still could fight it off. A negative PCR is to me, not so likely although possible with user error.

[AbcdeDooDah]

I agree with YaelAldrich. When I got my rapid the nurse explained that it could detect “exposure” meaning the virus is present in the nose. It does not always lead to an active infection. 

[matrips]

Hmm.  So maybe he had picked up a little bit of something.  Reliable tests would be SO nice.  Lol.  But at any rate, I’m so thankful he’s feeling better whatever it was.

[YaelAldrich]

4 minutes ago, matrips said:

Hmm.  So maybe he had picked up a little bit of something.  Reliable tests would be SO nice.  Lol.  But at any rate, I’m so thankful he’s feeling better whatever it was.

The tests are rather reliable. Please note I didn't say perfectly reliable. No test is perfect. The rapid test likely DID detect virus in the person's nasal cavities. He could have breathed it in anywhere at this point. The PCR test likely didn't pick up enough viral fragments to amplify to make a positive at that time. Because this person's immune system did its job. I'm very happy this person's immune system fought off the virus as unimmunized people fare particularly poorly as well can see from hospitalizations throughout the pandemic. May you and yours stay healthy and safe!

[Clemsondana]

While there could be a false positive or a false negative with either test, it's also entirely possible that both accurately report what was going on on the days that the test was taken.  While the PCR test tends to stay positive for longer because it can detect non-infectious genetic material bits, it's also possible that the infection was cleared completely over the 2 days.