False Positive?

[larrythelizard]

Anyone know if false positives from the NHS test are a 'thing'?

Friend of a friend who DH saw last week (although socially distant) has now tested positive (although no symptoms at all). All other mutual contacts are getting negative results, DH is obviously isolating until getting his results.

Any ideas?

Mutual contacts should be isolating for 10 days regardless of a negative test, as should your OH

They all are, I was just musing about the possibility of false positive tests

My A&E doctor friends have all had lots of false positives but I think they are those 30min lateral flow ones. And then once sent to lab they are negative/

False negative are more common

False positives on a proper lab test are very unlikely. I think the usual figure is 0.3% False negatives much more so. Can be as much as 30%.

It also depends on the pre test probability so at times where there is a lot of virus circulating (ie now) false positives are very unlikely.

I tested positive a couple weeks ago with what I thought was a minor cold. PCR test. No close contacts, I can’t trace it back to anyone! I’ve had no main symptoms at all. Mostly just feeling knackered. Some headaches. I honestly didn’t really believe it but still isolated of course. My OH tested 7 days later after getting a runny nose. Also positive. He’s had less symptoms than me. Just keeps sneezing. So I guess I really have had it. The chances of us both having false positives are vanishingly small & he hasn’t been anywhere to catch it elsewhere!

There are false positives but if they are asymptomatic I doubt you can spread it easily. I've yet to see conclusive evidence that asymptomatic spread is a thing.

www.bmj.com/content/371/bmj.m4436/rr-10