Thanks prunus, interesting post. What are the body's killer cells called? And does the eradication of the virus cells in someone who has recovered mean it is hard to test that someone has had the virus but is no longer infected by it? Because I was wondering if there could after a while be an army of post infection immune people available to help caring for the vulnerable groups, with no risk of infecting them.
At a top level the first line defence cells are called phagocytes, the specialist ones are called killer T cells; my knowledge is rusty so I thought I’d quickly read up on the system before replying to avoid giving out wrong information - I came across this
Viral Attack | Ask A Biologist which covers the whole process very clearly in much more detail and without the mistakes I would likely add, so I’m going to use the better part of valour and retire in its favour, if that’s ok...
In answer to your other questions - it’s not more difficult per se to test for post-infection immunity, it’s just a different test from the one being used at the moment, and takes longer to develop: the current test involves looking for the RNA of the virus directly, whereas post infection there’s obviously no virus left, so one has to look instead for the existence of the antibodies to it that were produced in the course of the successful fight. This is relatively easy to do once one has identified the antibody in question, but that takes time. It is needed though and people are working on it the world over.
Absolutely there could be an army of immune individuals to help care for those that need it, that’s the goal really, whether than immunity comes through having survived the disease or by vaccination (which is still a way off). The problem is systematically identifying immune people (though the register of confirmed cases can be presumed to be a list of immune people for those that survive, it’s not certain without an antibody test, plus that list probably doesn’t cover everybody, given the patchiness of testing).
(Aside - the fact that we can sequence an entire viral genome, develop target sequences against it and make a functional RNA amplification test that returns results in hours within a few weeks of a new virus turning up seems like witchcraft to me, as someone who used to do this kind of thing 25+ years ago when it would have been months of labour. This would have been a different kettle of fish had it occurred at the end of the last century, so we can count one small blessing at least. )