[philippoi]

I had some symptoms in mid-March as well, and actually on my birthday noticed I couldn't smell or taste nearly as well as normal. It was very apparent because I work as a barista, so naturally I rely on my sense of smell quite a lot, and I had really enjoyed the same green tea the day before and the day of my smell loss; it just tasted incredibly flat. My birthday meal and birthday wine were just a waste on me. My wife and I were tested for antibodies about 6 weeks later, when our son was born, and neither of us was found to have antibodies. It wasn't until around the first week of April that I first heard loss of your sense of smell was a symptom of COVID19. In spite of the antibody test, I suspect I had the virus. About how quickly does the antibody count drop if you develop specific antibodies to COVID19? I read somewhere that some people recovered from their infections without developing antibodies tailored to COVID19 and it was thought that these individuals overcame the virus due to their body's already existing store of antibodies for other types of Corona virus. I can't remember where I read that article now.

[nradov]

There is a huge variance in antibody response and duration between patients. It seems to correlate with symptom severity but there are other factors still not understood (possibly genetic). In some cases the innate immune system fights off the infection before antibodies are generated. In other cases the antibodies fade away quickly, but a high level of immunity is retained through memory T cells. Unfortunately there's no quick or easy way to do a specific T cell assay.

There is a hypothesis that prior exposure to other similar viruses provides a limited degree of immunity from SARS-CoV-2. It's plausible and fits some of the case patterns but we don't know yet if it's a significant effect.

[rindalir]

Same thing happened to me -- and I also tested negative for antibodies about five weeks later. My partner (who had more of a flu-like illness) did test positive for antibodies though, so I'm very certain I had it. My hypotheses are: test was not specific enough, i fought it off quickly with t-cell immunity, or my antibodies fell off very quickly since I really was not sick (I had fever of 100 for about three hours and some burning pain in my nasal cavity and that's it)