antibodies - can anyone tell me how they tell the difference?

[changingstages]

I had an antibody test via the Zoe app a while ago and it said 'No antibodies were found in your blood sample.' It also said: 'This test only looked for antibodies from an infection, rather than antibodies made after the vaccination.'

How do they know the difference? It's so interesting!

I am not at all knowledgeable about this, so hopefully someone will be along to explain it better than I can, but I know that there's several types of antibodies. Some are only produced after natural infection, and others are produced after a vaccine. This is how they can tell

N antibodies are post infection
S antibodies are post infection and / or vaccine

The vaccines will only cause you to create antibodies to the spike protein, at that is the only part of the virus included in the vaccine.

If you're infected your body will make antibodies to other parts of the virus as well as the spike.

As PP say, (to put it simply) N antibodies are made to the virus itself and therefore are only found after infection (in countries such as the UK where spike protein-inducing vaccines are used).

S antibodies are made to the spike protein so are made in response to either the protein on the virus following infection and/or from the created protein following vaccination.

I've had positive antibody test in July 2020, November 2020 and most recent one in July 2021 which said they were from infection. Not sure if this means I still have antibodies from having covid in march 2020 or if I've had covid since without knowing it.

Tim Spector at Zoe did a Q&A on this on Youtube.

The virus is made up of four different proteins. If you’ve had it, you’ll have antibodies to all of them.

The vaccine contains (or with Pfizer, contains the instructions for) just one of those, the spike protein. If your immunity is from the vaccine alone, and you haven’t had covid, you will only have antibodies to the spike protein.

More detail at www.technologynetworks.com/diagnostics/blog/amp/covid-19-antibody-testing-s-vs-n-protein-340327

ah thank you all, that's so interesting - and @boon I'll look up the Tim Spector Q&A. This kind of thing makes me wish I'd been better at/paid more attention in science at school because it's really fascinating!

Would the antibodies last from the very beginning. I'm convinced we had it after our ski trip in Italy when it all began but my test was negative

I'm almost certain I had it in March 2020 @whenwillthemadnessend but it didn't show any antibodies from infection - though of course that's more than a year before the antibody test. I wondered if it might as I was very unwell, but nope.

If they can't pick up from that long ago then the test is pretty pointless.

well... it shows that antibodies don't last. And that seems like quite useful information, no?

Antibodies to all infections fade over time. You body is primed to react the next time you come across the virus. Imagine if we kept high levels of antibodies to every infection we'd ever had. I feel like our blood would be chock full & most never needed. Just the ability to recognise & fight it off next time is what is needed.

Absence of antibodies does not necessarily mean you have no immunity, because they are only one element of the immune system. There are T-cells and B-cells, and the memory T-cells in particular ‘remember’ how to make antibodies, and will prompt your body to do so whenever they encounter the virus again.

(I’m not a scientist, this is what I’ve gleaned from watching John Campbell on YouTube)