I have antibodies - now what

epm-84

It might mean if you've developed some immunity that you are less likely to get significantly ill but then that might mean you are more likely to carry the virus around without realising, so strangely it might mean the case for you social distancing is stronger rather than weaker.

Also do note that the tests aren't 100% reliable so a very small number of people will be told they have antibodies when they don't.

minty777

I thought they were also testing (in patients/out patients)who are having bloods taken for other reasons not related to covid while they were sticking a needle in anyway.

silvercar

minty777 said:

I thought they were testing (in patients/out patients)who are having bloods taken for other reasons not related to covid while they were sticking a needle in anyway.

They are also testing those that are working in hospitals with a view to seeing the number who have antibodies.

getmore4less

onwards&upwards said:

getmore4less said:

Untill enough people get the tests the false positive will be relatively high. 

There is practically zero chance of a false positive.  It’s false negatives that are far more likely. 

Check the accuracy(specificity is the important one for false positives) of the tests available in the UK
a link and video that explains the situation.
https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/antibody-tests-guidelines.html
https://www.youtube.com/watch?v=NSRK41UbTEU
This is the key statement

For example, in a population where the prevalence is 5%, a test with 90% sensitivity and 95% specificity will yield a positive predictive value of 49%. In other words, less than half of those testing positive will truly have antibodies. Alternatively, the same test in a population with an antibody prevalence exceeding 52% will yield a positive predictive greater than 95%, meaning that less than one in 20 people testing positive will have a false positive test result.

one test available in the UK is 100% sensitive, 99.63% specific  false positive more likely than false negative.
they are estimating London has around 17% prevalence with the rest of the UK being much lower.

epm-84

silvercar said:

minty777 said:

I thought they were testing (in patients/out patients)who are having bloods taken for other reasons not related to covid while they were sticking a needle in anyway.

They are also testing those that are working in hospitals with a view to seeing the number who have antibodies.

There's also a suggestion that one city, possibly Norwich, could see everyone asked to do an antibody test so they have some idea of the number of people who have been infected and either not showed symptoms or not shown symptoms more severe than those of a normal cold or fever.

hb2

There is also the fact that 2 out of the 3 antibody tests produce unreliable results in people who are routinely exposed to animals
" Patients routinely exposed to animals or to animal serum products can be prone to this interference, and anomalous values may be observed."
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/890566/Evaluation_of_Abbott_SARS_CoV_2_IgG_PHE.pdf

Gonna-be-debt-free

Uxb1 said:

The who antibody thing is fraught with difficulties.
Firstly there there those who recover from the virus by their first-line innate immune system dealing with it so there is no need for their adaptive immune system to generate any antibodies: they are to an extent intrinsically/genetically immune to it - there is I think no test as yet for these people.
For those who do generate antibodies......
If the presence of antibodies does not make you immune to getting it again then the vaccine researchers have a huge problem.  A vaccine basically works by confusing your body to produce antibodies for a disease that it does not have, so when it encounters the real disease in the wild it is primed and ready to repel it at the first instance. So if there is no immunity from anti-bodies then a vaccine is unlikely. Additionally if there is no immunity then the human race has a real problem as you will continue getting it time and time again and those who suffer from it badly may not die the first time - but they most probably will the next time.
On the other hand if antibodies do make you immune for a period of months or years a quite different problem for HMG emerges.  For those who do have the CV19 antibodies it therefore follows that any form of social distancing makes no sense whatsoever: they cannot get it again and cannot pass it on.  So employers will only want to employ those with CV19 antibodies to avoid having to make any changes to the workplace.  This will lead to different classes of citizens, the employable and the unemployable, with antibody tests being regarded as an immunity certificate - along with all the problems of fake results being banded about.  For the young whose chance of dying is rather less than the chance of being murdered they would hence bizarrely actually want to get the virus and to recover from it to get the antibodies. (chicken pox parties anyone?)
So I can quite see why HMG would rather keep the antibody test to health care workers alone, and ban the public from getting private ones done- which I gather they have done by telling the labs to cease processes such tests, while continuing to muddy the waters about whether or not it means you are immune and continually pushing the keep to social distancing regardless mantra.

While that makes for a great dystopian novel, I'm not sure it's necessarily an accurate prediction of what might happen.

• Firstly - if antibodies make you immune then a vaccine is likely, which precludes the second-class citizens argument.  i.e. if a test for antibodies makes for more desirable workers, then a vaccine is likely to follow, making it at worst a short lived anomaly
• Secondly - even if antibodies don't make you immune, treatments for the disease are improving pretty much every day.  It seems likely there will be a point in the near future where anyone who catches it takes a cocktail of drugs that effectively treat it, preventing them from needing hospitalisation.  Analogously, there is still no effective long term vaccine for TB, but it is very, very treatable.
• Thirdly - there are other coronaviruses (the common cold) that we can't vaccinate against, however even though people don't get long term immunity from them, their immunity does improve over repeated exposure (even to different strains).  Typically the stronger a reaction someone has had the the first exposure, the milder their second exposure.  So in your scenario, the person who nearly died from it the first time, is more likely to have a very mild case of it the second time, NOT to die from it.