Interesting, but it’s a self-selected study, which means that you are not getting a true sampling of the population. In addition, the article does not say how many of those people subsequently developed symptoms. The head of the company running the study seems to think that at least some will later show symptoms.
“What it means in my mind, is that because we are screening the general population, we are catching people early in the infection before they start showing symptoms," Stefánsson said.