I recovered from COVID-19 back in April. I was fortunate: My symptoms, while nasty, were minor compared to others. I had the hacking dry cough and I was fatigued to the point where I would spend many hours on the sofa. But I never had breathing difficulties, nor required hospital treatment. Whenever the question of catching it again has come up since, I airily and hubristically said, "Oh, I've had it, and have antibodies to prove it." At least I did until Friday when my third antibody test came back negative. I was in shock. Even though it's not clear antibodies do actually offer immunity, I had treated my previous AB positive tests as a shield I could wave, crying, "Been there. Done that. I'm OK." Rightly or wrongly. Now my precious protection had vanished. I called the testing centre. "Surely some mistake," I said grandly. "I have previous tests to prove it." The centre, having not seen a case of a re-test losing antibodies before, went back to the lab to see what was going on. The lab responded, "Oh no, Mr Quest does have antibodies, just not enough to register on the scale." I had registered as 1 on the 'scale' and only those above 1.4 are considered to have enough antibodies to classify as positive. I needed to know more, so immediately launched into a whirlwind of googling, then battled through a scientific article on the Abbott SARS-CoV-2 IgG antibody test. IgG refers to immunoglobulin class G antibodies in your blood, which when washed, mixed and tumble-dried with other chemicals (as well as a load of other things I didn't understand), produces an antibody index, where the cut-off point is 1.4. And I had been cut off. Over the past five months, my evanescent antibodies had dwindled to meaningless and with it my bravado claim to protection. Now it seemed I was back to square one: vulnerable to COVID again. When I told my infectious diseases doctor in New York, he wasn't one bit surprised. He referred to the latest studies showing that antibodies do indeed weaken and dwindle over 90 days -- no one has had a chance to do much research beyond that yet. But, as my doctor continued, that's only half the body's defensive mechanism. T cells, an important part of our immune system's attack force, have virus memory. They will lay quiescent until (or if) the body comes into contact with Covid-19 again, at which point my immune system will fire up and start producing antibodies once more. It was, my doctor, said, "highly, highly unlikely that you will get COVID again this year ... medically improbable." I was then quickly admonished that none of this should lead me to abandon social distancing, hand washing and other anti-virus measures. Resilience, but no immunity? I relate all of this because it's another example of our collective tortuous journey with this disease. The circuitous progress of the pandemic creates fear, then hope, then back to fear again, seemingly with no end. I have seen many COVID recoverees quietly parade their antibody status as if it is a shield for life. Yet I would bet good money that if they took another test they would also discover that their armour has cracked, or has holes in it. I only discovered the curious case of my dwindling antibodies because I get tested frequently because of my travels for work. I like to think common sense tells me that I can't catch COVID again in the short term -- otherwise, we would have heard of many more cases of re-infection. So far there have only been a few outlier cases and they tend to have unique circumstances. Yet common sense must now be trumped by that hoary but voguish clich\u00e9: the "abundance of caution." I will only take common sense so far. This is all teaching me that what was fact yesterday, doesn't mean it's the same today. Experts are saying we know a lot more about COVID now than we did six months ago. That is true at the helicopter level, where governments make national policies, and also at the grassroots, as I go about my life. My new reality is that I no longer have the antibodies of which I was once so proud. I may have a resilience-based on T-cell memory and I am unlikely to be infected again, but I may! I just wonder what other "certainty" is going to crumble into the dust next. While I wait to find out, I will follow the rules.