please empty your brain below
Don't apologise for another post, you talk more sense on coronavirus than most!

TomH | 08.06.20 - 7:14 a.m. | #

A very worrying thought about the demonstrations at the weekend where there seemed to be Zero social distancing. Once can only speculate about the numbers of people who might have become infected with the virus.

RayB | 08.06.20 - 8:02 a.m. | #

If you just want to talk generally about the virus, Saturday's post is better suited for that.

diamond geezer | Homepage | 08.06.20 - 8:11 a.m. | #

The after the event test is the antibody test. Of course, you may know your status from a timely antigen test but I think you might have meant the antibody test - which seems to be turning up a disappointingly high number of negatives for those convinced by their February coughs.

dg writes: Fixed, thanks.

Brightside | 08.06.20 - 8:12 a.m. | #

A new antibody test is being trialled on (volunteer) staff at a local large hospital. It involves a full blood test, being administered by nurses (not phlebotomists or HCAs, and not just a finger-test, for some reason), and each nurse is timetabled to see/draw blood from 50 people a day. Results take "7 to 14 days" and are not guaranteed to be accurate.

Draw your own conclusions about whether nationwide antibody testing is going to happen anytime soon (or indeed, ever).

Blue Witch | 08.06.20 - 8:59 a.m. | #

Agree with TomH.
The best summary I have seen so far.
I’d like to see this posted far and wide, as there’s so much rubbish and misinformation out there and it could help people get a quick grip.

Herbof | 08.06.20 - 9:07 a.m. | #

The main problem I see with any testing is that it doesn't help with the "Didn't have it when tested but do now with no symptoms" scenario. Without constant retesting I suppose the whole thing relies on the numbers in that category being sufficiently low.

Andrew S | 08.06.20 - 9:38 a.m. | #

Your (over complicated) analysis doesn't include the many of us who believe they had CV last Christmas and without antibody tests have no means of knowing. I think I was one of those with very mild symptoms - and never felt fitter during this lockdown time.

davews | 08.06.20 - 9:42 a.m. | #

It's easy for me to stay home as I'm retired and like my home, so I've been taking precautions and will continue to do so. However, there are a number of people I know, as well as myself, who had a mysterious illness between November and January that, in retrospect, looked very like this virus. One friend's father died from it and he was tested for flu, which he didn't have. But, in the absence of clear evidence, I have to assume I haven't had it.

Z | Homepage | 08.06.20 - 9:49 a.m. | #

I'm in the "might have had it already, but not sure" category, as I definitely had SOMETHING in late March at a time when NW London had a lot of cases.

It's frustrating that the main test was non existent back then, whereas now there's massive capacity for testing.

Mikey C | 08.06.20 - 10:04 a.m. | #

One issue with the antibody test is that it has a high false positive rate (about 2%-6%) - so even if you are tested you had it it might be you haven't had it.

MK | 08.06.20 - 10:22 a.m. | #

A lot of the dangerous uncertainty comes from the fact that the symptoms are so variable. Most other diseases are relatively easy to diagnose.
But the danger of all communicable diseases is much exacerbated by our habit of living in cities. No other great ape does anything so foolish.

Malcolm | 08.06.20 - 10:34 a.m. | #

MK: My Superdrug positive antibody test claims:
Our lab test has a specificity of 100%. This means you can be sure that the antibodies they have detected are those relating to this coronavirus strain
Am I missing something here?

Freddie | 08.06.20 - 10:42 a.m. | #

The bottom line is that we should all treat it as "Have Not Had It" and act responsibly.
Sadly, from what I've seen locally, that doesn't seem to be happening in many cases.

Cornish Cockney | 08.06.20 - 11:24 a.m. | #

Where I live, the advice from the top during lockdown was "behave as if you've got it".

Very clear, sensible advice - and apparently effective, too: we now have zero active cases.

Betterbee | 08.06.20 - 11:42 a.m. | #

I enjoy the full range of your posts, but I appreciate these analytical summaries most of all.

Lorraine | 08.06.20 - 11:44 a.m. | #

I agree with MK’s concerns about accuracy - no test would appear to be better than a ‘bad’ test i.e. one that returned an unacceptable number of false positives or false negatives.

I also broadly agree with your assertion, DG, that testing is the only way to precisely know where we’re at right now. Though as Andrew S points out - without retesting, a single test remains but a ‘snapshot’ up to a set point in time, as far as my understanding of all this goes.

Full Fact also has some relevant info for the discussion here.

Sam | 08.06.20 - 12:28 p.m. | #

I’m off to get a serology test this afternoon, which made me try to guess the percentage chance I’ve had it.

The thing is, I believe these studies which show cross-immunity in about 50% of people from exposure to other coronaviruses. If I’m in this category, then I can’t really say I’ve had it, as I may have come into contact with a low dose of it many times and just batted it away. If I meet it again in a higher dose, I’d have to go through the other path DG describes of ‘getting’ it and developing immunity or dying of it.

With no illness after the 1st week in Jan, and a reported 30% chance of having developed immunity without symptoms, times the 17% in London who have antibodies, I make my chance of having developed antibodies (= have had it) to be about 5%. Add to that the 50% chance of cross-immunity, and it means I think I’m fine as long as I ‘stay alert’ and don’t do anything stupidly risky.

Jimmy | 08.06.20 - 12:29 p.m. | #

DG's infographics are the best!

Sarah | Homepage | 08.06.20 - 2:16 p.m. | #

See also...

Assume you've had it
Think you've had it
Suspect you've had it
Assume nothing

diamond geezer | Homepage | 08.06.20 - 2:21 p.m. | #

Regarding the currently used test for whether someone has the virus, I've seen two statements in the press, which can be rephrased as:
a) 'If someone tests negative, their chance of actually having the disease could be as high as 20%'
b) 'If someone has the disease, their chance of testing negative could be as high as 20%'

I understand that in general these statements are not equivalent, and wonder which of them might be true.

Bob L-S | 08.06.20 - 4:04 p.m. | #

There is an excellent article on the BBC News health page by Fergus Walsh covering the issue of people who had a similar illness over Christmas (including me) - apparently there was another corona virus going round then "OC43" not COVID19.

Surbitonian | 08.06.20 - 5:17 p.m. | #

I have recently had an MHRA approved antibody test privately at my local pharmacy. I was told (who knows for sure) that they provide a 99.9% specificity for positive results and 98% specificity for negative results.

I tested positive , the only reason I believed I may have had the disease was because of my complete loss of taste and smell for over 3 weeks back in March (nothing like I have experienced before).

On telling the pharmacist this, he said that he has tested 107 people who were sure they have had it, however only 6 of which subsequently tested positive. Out of those 6, 5 had reported loss of taste and smell.

Found that quite interesting and amazing that it is only recently they have added this to the official symptoms list.

Badger | 08.06.20 - 5:46 p.m. | #

In an effort to answer my own question by going back to primary sources I found this https://www.bmj.com/content/369/bmj.m1808 which has a useful graph of probability of having covid-19: depending on a) pre-test probability due to symptoms, exposure etc and b) test result.

Bob L-S | 09.06.20 - 10:09 a.m. | #

"the hads and the had-nots"

tops | 10.06.20 - 8:50 a.m. | #

One way to personally help improve infection data is joining the covid.joinzoe.com study. 3m people each day spend 1 minute reporting their own & partners/ kids/parents/ health. Very easy but has collected tons of useful data that's shared with the NHS & supplements the government's efforts. It's based on direct personal experience, not representative samples, so they need everyone. They're a bit short of data on over 70s, including people in care homes.(Relatives or carers can report for them if they can't do it themselves).

Jenny | 10.06.20 - 9:08 a.m. | #











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