Odds of two false positives in same household?

[SoleSurvivor111]

OH had (entirely necessary) contact with his sister at the weekend. They wore masks, washed hands etc, but it was an emergency situation so there's a good chance there were slip-ups in safety.

She tested positive two days ago.
The same day, I had a cough and OH had a slightly sore throat, so we got tested. Both came back negative.

Now I know that's quite a short amount of time between the possible infection and the test, which would maybe account for no sign of virus.

But isnt it also a very short time between the possible infection and the symptoms? And if symptoms were present (are present - I still have a cough) then shouldn't that mean virus is established enough for a positive result? And wouldn't at least one of us have shown positive?

Confused

I OBVIOUSLY mean two false negatives haha. Head all over the place. New here and can't find an edit button

Why are you confused? There are other, normal, seasonal illnesses around at the moment.
You had symptoms, got a test and it was negative.

Following as we have had a very similar situation with 4 negative tests yet symptoms after contact with a positive case. Positive came through three days after we had been in contact.

My understanding is the majority of symptoms come within 3-7 days of contact.

Grr last response didnt post.

So, this doesn't feel like a cold. I have a lot of colds each year. This is a dry cough, not chesty. No congestion.

We lost my MIL this weekend to it. And obviously there's arranging to do. My SIL and my OH are isolating (because of her positive and his contact with her). I could be a lot more helpful to them if I could end isolation based on my - and OHs- negatives. But I'm concerned I might have it via him and could spread it, even though as a third party contact I could leave isolation because he and I are negative.

If that makes sense..?

So my son tested positive on Friday. I had a cough Saturday as did my husband so we got tested then. Negative. Cough has got worse and we got a Zoe app request to do a new test. Husbands has come back positive and fully expect mine to be the same. So yes it’s possible.

Right thanks, that's helpful. So looks like I'll keep isolating and see how the cough gets on, and see about new tests. Are they okay with you ordering a second test for the same reason then? We don't have any of the apps.

If you test too early/late the results have more chances of coming back false.
Having a short testing window isn't really helpful either when it can be 5+ days before people realise they might have it and have managed to get a test.

The false positive test rate is around 4% (although some studies suggest it is much lower). On that basis, the odds of two false positives is around 0.2%. However, that is a purely statistical measure, and doesn't take account for the potential of a whole batch being affected, in which case the false positive test rate could be 100%. Sometimes trying to apply stats to individual circumstances just doesn't work!

When I got ds a test the other month, I was adviced over the phone if it came back negative and symptoms worsen or still there after a week without getting better, another test could be requested because of the too early/late thing.

The Zoe app is really good. It's also going to start doing something to track schools/students. This is entirely different to the governments T&T

@KTD27

So my son tested positive on Friday. I had a cough Saturday as did my husband so we got tested then. Negative. Cough has got worse and we got a Zoe app request to do a new test. Husbands has come back positive and fully expect mine to be the same. So yes it’s possible.

Also - sorry for the questions when you you're feeling poorly, but does your son live with you? So, you could have picked it up days before the symptoms started, or any time up to then? Just because OH only had contact with his sister at the weekend and hasn't seen her in person before that or since. So either he definitely got it at that time or he didn't, the window of time is pretty solid in our case.

The false negative rate is between 2% and 33% ( Recent Lancet publication ).
At 2%, two false negatives is 0.04% chance. At 33%, two false negatives is nearly 11% chance.

I'm sorry about your MiL

Thank you. I haven't really had time to take it in yet, to be honest. This virus is AWFUL and it's taken a true angel from us. And all this isolating and not seeing each other at the worst of times...

I just want to know if I can safely de-isolate without risking others' safety, hence my confusion. As I'd be a lot more useful doing essential stuff for them than stuck in, if indeed I don't have it.

@SoleSurvivor111 yes he does - he’s only 4
His bubble shut Tuesday morning last week so we think he picked it up Monday or the Friday before at the earliest. His symptoms have been very mild so it’s hard to say when they started. We tested him Friday because his sister started to cough a lot and he’d had a mild cough on the weds/thurs eve.
I’d say my symptoms started Saturday got worse Sunday then with a negative result I decided it was fine now there’s no denying the cough. Strongly suspect my daughter had it too.
Eugh.

If you've had contact with a positive person you need to self isolate for 14 days. Even if you get a negative test.

It seems like your SIL was at her infectious peak if she tested positive two days after your husband saw her.

I'm really sorry about your MIL and the timings. It must be really difficult

Oh no! How you all feel better very soon! And thanks, that timing advice is a big help. I think I'll stay isolated til Monday and if he same/worse I'll ask for another test.

@SoleSurvivor111 I don't think that you can de-isolate.

Your DH was in contact with someone who tested positive which would automatically be a 14 day isolation period from the date of contact even if a negative test is received during that period.

He has since developed symptoms (not clear on if this includes the main 3 cough, temp, loss of taste/smell) so you and anyone else in the household needs to isolate for 14 days even if you get a negative result.

You took the tests within 2 days of contact so not necessary long enough for virus to be detectable for a test.

@nodogz

If you've had contact with a positive person you need to self isolate for 14 days. Even if you get a negative test.

It seems like your SIL was at her infectious peak if she tested positive two days after your husband saw her.

I'm really sorry about your MIL and the timings. It must be really difficult

Yeah that's why I'm confused - I havent had contact with a positive person, only OH has. So he has to isolate. But he hasn't really got ongoing symptoms, a sore throat for a day but that could have been anything, and it went. So he's negative, I'm negative, he isolates, I don't - but I'm the one with slight symptoms.

That's where I'm confused about this cough and what to do for the best. Odds of me catching it off him, if his contact was so recent and he's not infectious enough for a positive test, seem so minimal?

My SIL had Covid and her husband didn't get it
My BIL had Covid and his girlfriend didn't get it.

I've been self isolating because someone j work with tested positive I come out tomorrow and I haven't had any symptoms.

If the tests negative it's negative