Doctors in the United States are bracing for a “twindemic” of flu and coronavirus spikes. Germany bought extra flu vaccine doses. Tens of thousands of people in Britain are looking up “worst cold ever” on search engines.

In countries with relatively high vaccination rates such as the United States and in Europe, it could get tricky for the immunized to tell a nasty cold from a breakthrough case of covid-19. It’s also hard to predict how bad this flu season will be after last year’s historically low flu rates during lockdowns.

With children back in school in many parts of the world and travel picking up in tourist spots, health-care professionals worry that the flu season could come roaring back and are urging people to get their shots.