Guide to what happens if you catch flu and COVID-19 at the same time?

We’re facing a “twindemic” of both the seasonal flu and COVID-19, and research shows it’s possible to get sick with both respiratory illnesses at the same time. Unfortunately, history proves people haven’t done a good job of taking the flu seriously enough.

Just 45 percent of adults in the United States got the flu shot last year, according to the Centers for Disease Control and Prevention, even though the seasonal version of the disease is deadly, killing an average of 37,000 people every year over the past decade. Having both diseases in play simultaneously threatens to tax our health-care systems and puts lives at risk like never before. That’s not to mention the real possibility that a strain of bird flu lurking at poultry markets could jump to humans and cause an overlapping pandemic.

National Geographic asked two infectious disease experts to weigh in on what’s at stake with this year’s dual threat, and why we all should get vaccinated against the flu as early as possible. The following interviews have been edited for length and clarity.