“Commonly known as the stomach flu, norovirus has been around forever, and has become the leading cause of gastroenteritis or inflammation of the intestinal tract that causes vomiting and diarrhea,” says Dr. Edmund Milder, a pediatric infectious disease specialist at Rady Children’s Hospital and UC San Diego Health.

The highly contagious stomach bug calls for “enhanced precautions” — the highest level of cleaning.

Despite millions of cases of norovirus in the U.S. each year—and a current surge in outbreaks—there is still no vaccine for the stomach bug. Here's why it's taking so long, and how close we are to a norovirus vaccine.

Norovirus is surging across the U.S., with case numbers higher now than they've been at the same time in more than a decade, according to the U.S. Centers for Disease Control and Prevention (CDC). There is no antiviral treatment for the miserable but thankfully short-lived illness,

Recovering from norovirus gives the body a certain level of protection for some time. But it's important to know if it's possible to get infected again.