There's evidence that some subset of younger, healthier people may not produce measurable IgG antibodies. There was an initial study in China and additional pre

There's evidence that some subset of younger, healthier people may not produce measurable IgG antibodies. There was an initial study in China and additional preliminary work in Germany and Mayo Clinic. """ [Elitza Theel's] team has found that it's mostly the sickest patients — those who've been hospitalized — who produce IgG antibodies. And it appears that a small percentage of patients with milder cases of the disease aren't making the robust IgG antibodies. "This is very preliminary," Theel warned. "But there might be a differential immune response between very sick individuals and individuals who have a more mild course of disease." """ https://www.nbcnews.com/health/health-news/antibody-tests-can-t-yet-say-who-s-immune-covid-n1193321 https://www.nbcnews.com/health/health-news/antibody-tests-ca... Their definition of "mild" means that you didn't require hospital care. So if you're under ~30 and otherwise healthy, you may be one of the people who beat the infection by some other mechanism. Or you just had influenza. It's impossible to know for sure right now.