Is Omicron possible with negative test results spaced this way?

January 5, 2022 5:43 PM

Is there any chance this was Omicron given this timeline? Symptoms Dec 20, tested negative Dec 21. Symptoms persist until now, but I had a second negative test Jan 2, 12 days after the first one. Is there any chance I could have had Omicron anyway between those two negative (PCR) tests?

It started with a sore throat, and turned into a nagging, horrible cough worse than I've had in years, with only some other mild cold symptoms. The cough is a teensy bit mucusey, so not totally dry, but I wouldn't call it wet either. The timeline and symptoms line up so well for Omicron, I can't believe it's not - that would be one heck of a coincidence. Is it possible I had it but missed being able to test for it given the dates testing was available to me?

This is more curiosity than anything, and I have a doc appointment on Friday for this cough anyway. But I am scheduled to get my booster tomorrow and it did occur to me this might mess with it, but I since I tested negative recently I think I'm ok?

posted by cgg to Health & Fitness (9 answers total)

From everything I've heard, yes this is a very feasible scenario in a vaccinated person. It's also possible you just never quite spiked a detectable viral load, or only did so around what appears to be the big Day 5 benchmark.
posted by Lyn Never at 5:51 PM on January 5, 2022 [3 favorites]

If you'd used a rapid test, this would be possible, but it would be extremely unlikely that you would test negative on a day 11 PCR if you had COVID.
posted by ryanbryan at 5:52 PM on January 5, 2022 [12 favorites]

You're more likely to get a negative PCR if you test too early. If you had only the first negative PCR I would say it might be possible, but the second one being negative too suggests it was just a nasty cold.

Basically what ryanbryan said.
posted by fight or flight at 6:01 PM on January 5, 2022 [3 favorites]

I had the same exact situation, super nasty cold, coughing up blood, food tasting weird, negative rapid negative PCR.
posted by sandmanwv at 6:22 PM on January 5, 2022 [1 favorite]

Same for me. They said RSV is going around and has similar symptoms.
posted by waving at 7:14 PM on January 5, 2022 [2 favorites]

Around Dec. 18th, a family member had a nasty cold with all the "classic" Omicron symptoms. PCR test negative. He recovered and then on Dec 28 he was exposed to Covid. He PCR tested positive on Dec 31st.

In other words, this is an anecdote about how there are other nasty respiratory infections going around this year.
posted by muddgirl at 9:17 PM on January 5, 2022 [1 favorite]

I'm pretty certain I had covid a year ago (unmistakable respiratory symptoms, doctor agreed), but I waited a week to get tested and the PCR came back negative. So, sure, it seems possible.
posted by toastedcheese at 3:28 AM on January 6, 2022

Did you swab your throat when you tested? This seems key with Omicron.
posted by Riverine at 11:47 AM on January 6, 2022

PCR rarely gives false positives but it actually has a rather high false negative rate. You can google "PCR false negative" to see a bunch of studies, but the false negative rate is not like 0.1% or 1% or 2%. It is more in the 20-30-40% and even 50%+ depending the specific circumstances and situations. Also the rate is quite a bit higher early on, before symptoms develop and even for a day or two after.

Here is one study that pegs the false negative rate at about 30%.

So your exact mileage may vary, but just under the assumption that both of your PCR tests had a 30% false negative rate, that means the chance of two-in-a-row false negatives is about 9%.

So to the question any chance this was Omicron? you would have to say, yes there is some chance you had some form of covid and the two PCRs didn't pick it up.

It may not be the most likely possibility but it is a possibility with roughly a one-in-ten chance of happening.
posted by flug at 8:49 PM on January 6, 2022 [1 favorite]