Sorry if this has been asked and answered, I skimmed and read some threads and might have missed it, but my question is can a common cold, runny nose or sinus infection - that one typically gets every Winter - cause a positive Covid result? I've seen arguments for both sides and just curious what the general consensus was here from the Aggie medical community - and you other guys/gals as well - lol. TIA

And a follow up question - is either type of test (Rapid vs PCR) more likely to generate a false positive?

I don't know if it can, but in my personal experience and the experience of my friends and family, it hasn't done that. I was tested when I had cold symptoms- negative. I know a handful of other people with cold symptoms who were also negative.

No, it can't. False positives from either a PCR or antigen test are extremely rare.

Strange things are possible though - for example you get an asymptomatic/symptomatic COVID infection and then a few weeks later (after you've recovered), get a cold, and get tested for COVID and test positive since we know people can test positive for weeks after recovery from COVID.

But the simple answer is no. Maybe, hypothetically, one in every few thousand tests.

SoupNazi2001 said:

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cc_ag92 said:

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I don't know if it can, but in my personal experience and the experience of my friends and family, it hasn't done that. I was tested when I had cold symptoms- negative. I know a handful of other people with cold symptoms who were also negative.

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I was positive and all I ever had were minor cold symptoms.

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Same here. If I had not lost taste and smell, I would have thought I had a cold, since I just had a very minor stuffy/runny nose for a few days.

" If I had not lost taste and smell"

This is the difference in most cases.

We know.
But that doesn't mean a cold caused your symptoms. It just means the Covid virus caused symptoms similar to a cold for you.

aggiederelict said:

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" If I had not lost taste and smell"

This is the difference in most cases.

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Yes and no. The common cold/a stuffy nose can cause loss of taste/smell, too.

And not everyone loses taste/smell, so you could have just a runny/stuffy nose and have Covid.

If you have either of those symptoms right now, you should be careful who you come in contact with.

Can and does are two different things. The symptoms people describe with Covid with respect to smell and taste are quite different from your common cold. Losing your sense of smell/ taste for 8-10 weeks is not a sign of a common cold.

aggiederelict said:

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Can and does are two different things. The symptoms people describe with Covid with respect to smell and taste are quite different from your common cold. Losing your sense of smell/ taste for 8-10 weeks is not a sign of a common cold.

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When you very first lose taste/smell, you might not associate it with Covid. Especially if you have a stuffy nose, too. My first day of symptoms, I still had partial taste and smell, and when I took Sudafed and Flonase, the symptoms subsided.

It gets described as a "sudden onset loss", but it doesn't always happen that way.

I didn't get tested until I lost taste and smell completely, which didn't happen until days 2-3. I was cautious enough to stay home from work right away, but on day 1, my symptoms definitely seemed just like a (very) minor cold.

I got tested because, when I thought about it, I realized that I'd never had a cold that cause me to completely lose taste/smell. But it took a couple of days for that to happen.

Exactly. Better to error on the side of caution. Under normal circumstances move on about your business.

bigtruckguy3500 said:

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No, it can't. False positives from either a PCR or antigen test are extremely rare.

Strange things are possible though - for example you get an asymptomatic/symptomatic COVID infection and then a few weeks later (after you've recovered), get a cold, and get tested for COVID and test positive since we know people can test positive for weeks after recovery from COVID.

But the simple answer is no. Maybe, hypothetically, one in every few thousand tests.

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Thanks! Good to know. I'd read that the rapid (antigen) tests were less reliable because they test for antigens of all diseases caused by coronavirus. Not just Covid 19. And Since some Common colds are caused by Coronavirus you could test positive without having Covid 19.

Also read that rapid tests cause more false negatives.

So I was confused. I'm guessing you can't really go wrong with either if you have minor cold symptoms? Just got get one or the other?

You can always get a rapid test and ask them to send a sample off for PCR, too. That's what I did, since I had read there are issues with false positives with the rapid test (although, I think false negatives are more likely/common).

The only downside is you get a q-tip shoved up your nose 4 times instead of 2.

TXTransplant said:

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You can always get a rapid test and ask them to send a sample off for PCR, too. That's what I did, since I had read there are issues with false positives with the rapid test (although, I think false negatives are more likely/common).

The only downside is you get a q-tip shoved up your nose 4 times instead of 2.

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Oof, I wondered this but was afraid to ask. First, sounds like for rapid and pcr, a swab in each nasal. And even worse, it sounds like if you ask do both, they don't use the same swab, your just getting rapid (brain stab left and right) and pcr (another brain stab left and right). Could they do 2 smaller swabs and do it in one go?

The rapid test is falsely negative about 50% of the time. The PCR is falsely negative on average about 20% of the time, depending on how long you've had symptoms and the severity of your symptoms, as well as whether they do the nasopharyngeal swab (tickle the brain) or the anterior nares swab (just about a centimeter inside your nostrils). I've seen several people with loss of smell/taste test negative on PCR, and their close contacts test positive a few days later.

The main advantage of the rapid is to allow you to start contact tracing sooner. Now, if you're a VIP and have free access to the rapid testing, then by testing every couple days you can potentially overcome some of the high chance of a false negative. In general, I recommend sticking with the PCR.

And, as always everything should be taken in the appropriate context, with the appropriate precautions.

Tabasco said:

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TXTransplant said:

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You can always get a rapid test and ask them to send a sample off for PCR, too. That's what I did, since I had read there are issues with false positives with the rapid test (although, I think false negatives are more likely/common).

The only downside is you get a q-tip shoved up your nose 4 times instead of 2.

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Oof, I wondered this but was afraid to ask. First, sounds like for rapid and pcr, a swab in each nasal. And even worse, it sounds like if you ask do both, they don't use the same swab, your just getting rapid (brain stab left and right) and pcr (another brain stab left and right). Could they do 2 smaller swabs and do it in one go?

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Don't know if they could do it all in one. Probably not since most places have to send the PCR sample off to some other location.

I will say, the rapid swab wasn't as severe as the PCR. My initial reaction was "this wasn't so bad". The swab for the PCR definitely felt like they shoved it up my nose farther, and it made my eyes water.

I wouldn't call either swab painful, though. Just a minor irritation.

If you think about it logically, a rapid antigen test would only test positive if you are far enough along to have a higher amount of virus (because it will react to a straight sample). That is why you are more likely to have a false negative. A PCR test is very specific because it is designed to bind to small sections of the RNA of COVID-19 and amplify them if they are present.

Also be aware that there is a difference between rapid antigen test (<30min) and a rapid PCR test (our hospital turnaround time is 4hrs for this one).

All in all, as said above, false positive because of cross reactions with other colds is possible but not likely.

What you're asking is about a test's specificity, "a test's ability to correctly generate a negative result for people who don't have the condition that's being tested for (also known as the "true negative" rate)". The PCR tests have very high specificity (~97% to 99%). Some of the other antibody testing methods have lower specificity.