False positive or had it and didn't know so test was fading?

[Nsws2015]

My older son tested positive Sunday night, he is still testing quite bright positive today. My toddler, I tested him monday and he was negative, and again Wednesday as my dad was wanting to take him out. That test came up with an obvious line but not as bright as the control line. He had had an upset tummy for a couple days, but wed/Thurs the nappies ramped up, pooping/wet farts which led to a very sore bum for which the drs had to prescribe a cream over the phone.

He's had no temp, a crusty nose rather than snotty, has been eating and drinking as normal but waking in the night unsettled when he normally sleeps through. Have tested him again today and his test came back negative. My husband thinks the test on Wednesday must have been a false positive, I'm not convinced but could it be possible?? I've attached a pic of his test on Wednesday

It's more likely that it was a false negative than a false positive.

I did 2, the nose and throat one to begin with but only nose and when that came up negative I thought maybe I hadn't swabbed enough as the nose/throat swabs are quite flimsy! So I did a nose only one and got a good swab from both nostrils and that came back negative too! I'll test him again tomorrow as well though

I got negatives every time I did a lateral flow when I had Covid. I had 2 positive PCRs and symptoms so I definitely had it. I think people rely too much on lateral flow for definitive answers, they're not always accurate.

I did 2 LFTs earlier in the week within minutes of each other - one was positive and one negative. PCR was positive (not unexpected given close contacts had all come down with it). My LFT line was no darker than that one. I haven't had a temperature and only a bit sneezy, slightly scratchy throat and a headache that has eased today.

I think it sounds like your toddler was symptomatic. Many children have upset tummies with it. I reckon the negative one is wrong. If your child doesnt have enough virus in his nose, it will obviously test negative or it could be as your say, he had it and is now testing negative for it.
I think a throat swab is more accurate tbh but much more difficult to do with a toddler.

That test is positive.

Don't see why your DH thinks he hasn't had Covid? There is a wide range for how quickly people test negative again.

It's possible it was a false positive, but given you have had covid in the house, he's had some symptoms and he had a positive test I would say it's really unlikely. Isn't it something like the chances of a false positive are 1 in 1000 - and the chances of a false negative are much higher. Not everyone gets a temperature with covid. Plus toddlers are hard to test thoroughly as they're a bit wriggly! I hope they're both doing ok now.

A line no matter how strong is a positive and he should isolate until day 5 and then see if you get a negative that day and the following day, then he can come out of isolation. Although this is advice, it’s not legally binding.

I think he had it and the test I had done Monday was a false negative, when I had it at Christmas I tested negative in the morning and then I tested again that avo as I felt like I had been hit by a bus and got a line straight away. Both are fine now though, older son was only feeling rough sunday, he is now bored and missing his friends and little one just grumpy cos of his sore bum! I will test him again over next couple of days to be sure though, and we have no plans to be going anywhere anyways....and I don't fancy going anywhere and trying to change a wriggly toddler with cotton wool and water right now anyways!!