Half the family positive, half negative - HOW?

[ShirtyShirly]

1st DC tested positive on Friday last week, last contact with a positive case the Monday before.

2 further DCs tested positive on Sunday. Me, DH and 1 DC were negative.

The three of us who were negative retested yesterday and again negative despite having mild cold symptoms! Similarly positive DDs boyfriend also tested negative.

How? We’ve all been isolating since last Friday. Not really able to isolate individually and as I assumed we’d all have got it anyway when 1st DC tested positive, we haven’t been making efforts to sanitise door handles etc. House isn’t big. They are in and out of their rooms, in the kitchen, share a bathroom.

DH and I were extremely ill with a mysterious illness in February. It was flu like but not ‘flu’. I had a cough for 3 months afterwards. Negative DC was also unusually ill (in bed practically unconscious for two days), two of the positive DCs had temps and coughs but mildly. DD’s boyfriend was really ill with high temp and cough on the summer but he never got tested (he wasn’t with DD then).

Is it possible that was CV and we have antibodies so didn’t get reinfected? I read yesterday that antibodies can last for 6-8 months or longer but the evidence isn’t there yet as CV’s not been around long enough obviously. Apparently only 25 people in 52 million have been found to be ‘reinfected’ so far.

I can’t find much info on whether you would test negative if you had been reinfected but had antibodies.

Anyone know.

Same as when one child gets a stomach bug at school, but no one else does.
Or when one of my children got impetigo, but the other didn't, despite them sharing a bed before I realised.
Or not everyone getting chicken pox.

Not everyone exposed to a virus develops the virus.

It’s a strange virus. I know 3 people who have had it, yet none of their family did. Then I saw on the news tonight a lady and her two sons who all died within 3 days of each other.

I did read that people who have had a similar flu virus in the last 6 months may be less likely to get infected. It was something to do with T cells which I didn’t really understand.

Few weeks ago DS had a cold, gave it to little DS, who gave it to DH.
DH coughed & got tested for C19 (negative).

I never got ill at all. Not every germ spreads.
I think I read C19 attack rate was 30% within households. So 70% of housemates won't get it even when there is a live case they are exposed to.

T cells

Wife had positive Corona test early October, I tested negative same day. Both had symptoms before the test. The next few days she deterioted badly. Ended up in hospital for a few days before coming home and us isolating for the remainder of required time.

My symptoms cleared up in a few days and I was fine. My 5 Yr old son had no symptoms at all.

Wife still poorly, off work etc.

I did antibody test last Wednesday- results back on Friday - No antibodies!!

So either I never had it, maybe just had a cold. But seems crazy (although not uncommon) that I or my son didn't go on to catch it from her as my house isn't big at all.

Having spoken to doctor friends they are firm belivers in the T Cell theory that normal people can't test for and that's why I never developed antibodies as had pre existing immunity.

www.bmj.com/content/370/bmj.m3563

Very pleased I avoided it as my wife (41, teacher) was in such a bad way. If I'd got it bad I don't know who would have looked after my son

I've tested positive twice in the last 4 weeks, and my 3 month old, 2 yr old and husband have all tested negative 3 times in that period (repeated testing due to planned op for ds). Doctors were surprised!

3 families we know - husbands had symptoms, tested positive. A few days later, wives started to have symptoms, tested negative. 2 of the wives restested a few days later due to worsening symptoms, still negative. Kids never had any symptoms.

I read somewhere that you are subconsciously attracted to people with opposite “immunity” (or whatever the technical terms is). So if my DNA/body is good at fighting ABCD, my husband is likely to be good at fighting EFGH. And indeed, we never catch each other’s bugs.

Totally bizarre/fascinating.

My brother in law had coronavirus in spring (tested and confirmed as he's a doctor). My sister isolated but never caught it and tested negative. My sister caught it last week. So she clearly isn't immune. I think it's odd she never caught it from brother in law.

I know of a family where multiple members had the virus and tested positive but others didn’t even those there were small children infected and they were in constant close proximity. I too thought that was really odd.

This is what happens with viruses. They are also finding some people are more infectious than others.

If you have one Covid positive person in your house, it is worth isolating as much as possible.

T-cells provide longer immunity than antibodies.

@LAWonder yes I read that about immune systems. It’s really fascinating. It means you go on to produce children with strong immune systems.

My husband and I are never ill at the same time. I once had norovirus and he still slept in the same bed as me and cleaned up my sick and was never ill.

I think there isn't enough understanding (including by me) of viral load. I've read this is important in other diseases too - so if you get a much bigger viral load then you're more ill. It's been shown wearing a mask helps ensure that if you catch it, it's milder due to lower viral load.

I think sometimes people who get it badly have had a big viral load. I've known a few kids get it very badly despite the general consensus that kids in general don't get ill and I've wondered if they somehow had a big viral load.

Added to this it seems that some people are 'superspreaders' and drive the majority of the spread - so if you get a high viral load from a superspreader perhaps you'll be more ill but lots of people hardly infect anyone or no-one at all - the opposite of superspreaders?

And yes, immunity too.

It is an interesting question.

I also read somewhere that if symptoms are mild you may be more likely to have a false negative test (and that false negatives are quite high- I think one in 5?) but you'd think if you did two tests it would get over that problem.

Without wanting to cast a more negative view those family members who have tested negative havent got it yet but there is a reason why contacts have to isolate for 14 days- you may be pre symptomatic not actually clear.

Or you might be immune, but it seems to early to tell if you have been in frequent contact with confirmed cases ...

Surely it's not that surprising? You've probably had it and are immune. Or you just haven't caught it (or haven't caught it yet). People in the same household don't always catch each other's illnesses.

Just like not all family members all have a cold, flu, stomach bugs and more. It's all down to the individual.

I had it back in March. I had two children here, a friend coming in and a community nurse. No one caught it.

My dd got it back in June via work.
My ds got it back in October/November from school (he'd been 2 places school and home).

The lasting immunity does worry me as I was really ill with it the last time and I was healthier then.

I think you’re right @IloveJKRowling about viral load /infectious dose? But yes, I remember reading that is why doctors became more ill, they were getting exposed to multiple doses. Then you’d hear of whole families becoming very ill as the initial doctor passed on a larger dose?

So would that follow if you pick up the virus from someone asymptomatic you would get a milder form of illness? It’s so interesting. If you pick it up from a surface you become less ill than if someone coughs in your face?

Tests are not 100% accurate.

Thanks for the link AxMan76

I have a reasonable understanding of immunity and have been banging on about T cells and infection derived immunity for months so love coming across articles like this.

I read somewhere that you are subconsciously attracted to people with opposite “immunity” (or whatever the technical terms is). So if my DNA/body is good at fighting ABCD, my husband is likely to be good at fighting EFGH. And indeed, we never catch each other’s bugs.

I'm from the south of England, DH from the north and we rarely get the same bugs. If one of us gets a bug the other always says 'you and your northern/southern bugs'. DD very rarely gets ill and didn't even as a young child. Maybe she has hybrid vigour.

You see I’m not a scientist and I have been talking about my the role of T-cells since about April. Just based on other Coronoviruses and the other SARS virus. I guess antibodies are easier to measure? But it seemed to be all along that T-cell immunity would be crucial in this pandemic. I don’t understand why only now the research is being done (well I think June then results out now)

Why did we focus on antibodies for so long and ignore the role of t-cells? Any scientist out there know?

I read somewhere that you are subconsciously attracted to people with opposite “immunity” (or whatever the technical terms is). So if my DNA/body is good at fighting ABCD, my husband is likely to be good at fighting EFGH. And indeed, we never catch each other’s bugs.

Fascinating if it's true! Come to think of it, dh and I don't catch each other's stuff often either. I catch things from the dc.

Delatron antibodies are easier and cheaper to measure than T cells. The BMJ article posted on this thread explains a lot and is quite an easy read.

The other element is that the government decided back in March that the concept of herd immunity was politically toxic so have shied away from any talk of naturally derived immunity since. But it is biological fact that infected people will respond with an immune response and it would be amazing if that didn’t provide any future protection or impact the course of this pandemic! Even SAGE finally conceded this a couple of weeks ago in a short article they released.

Tests are inaccurate.