Well, even the antibody titre isn't foolproof (some people do not react or have their immune system later wiped). However having no antibody titre is pretty goo

Well, even the antibody titre isn't foolproof (some people do not react or have their immune system later wiped). However having no antibody titre is pretty good sign you never had it. Not sure if there's a portable cheap blood test for it yet. Should be one, like for the active disease.