Two in December and one in January had symptoms. The one in January was just back from Germany and has not been tested. The other two tested positive for antibodies. One of them had moved from Canada in the prior two months.
Covid-19 did not show up in Germany until mid January.
According to the animation linked below, the first German case was infected on Jan 20 at a meeting with a Chinese woman from Wuhan. Unless your relative was at that meeting, the chance that he was exposed to Covid-19 is exceedingly low. And had he been at that meeting, I’m sure public health officials would have contacted him already.
This *is* cold and flu season. Not every respiratory illness is Covid-19. And who knows, with social distancing and so forth, the incidence of common colds and influenza could be unusually low this year.