Many people have gotten used to rolling up their sleeves for flu and COVID-19 vaccines. New immunizations are also available to combat respiratory syncytial virus , or RSV, for those at high risk of illness. Although the one-time shots reached pharmacies last year, fewer than a quarter of those 60 or older nationally had been vaccinated as of May.

Even in Florida, not many older adults have gotten the shot yet. That’s telling for a place with a high concentration of seniors because, while the virus has traditionally been thought of as a childhood ailment that affects babies, older adults can suffer from it, too. And Florida, with its humid weather, is the nation’s ground zero for RSV.

Each year, infections typically start in Florida and the Southeast before spreading to other parts of the United States, according to the University of Florida’s Emerging Pathogens Institute . The Sunshine State’s RSV season runs longer than anywhere else in the U.S.

, the institute said. There and in other places with tropical, humid climates, outbreaks can occur sporadically throughout most of the year, according to the institute. That means RSV season is already underway in some parts of Florida and is coming soon to the rest of the country.

Here’s what to know about it: Q: What Is RSV? The respiratory virus is common but gained more widespread recognition amid the COVID pandemic. In medical school, many doctors were taught that RSV was an important pediatric illness but not a major .