“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.

The highly contagious illness has reached its highest levels for this time of year in more than a decade, according to the latest CDC data.

Health First's chief medical officer gives advice on how to avoid norovirus, one of the most common causes of the 'stomach flu.'

One of the ways that it spreads is through a common (and gross) symptom: projectile vomiting, which is one sure-fire way for the virus to spread out, says Foster. Bathrooms are often a big source of contamination, adds Mahesh Polavarapu, MD, the medical director of emergency medicine at NewYork-Presbyterian Westchester Hospital.

"It is too early to tell if this strain is associated with more severe norovirus disease but likely lower population immunity is the reason for the early surge of an otherwise seasonal increase of this virus," Jan Vinjé, head of the CDC's CaliciNet system, told CBS News in an email.

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.

According to the World Health Organization, norovirus is the leading cause of acute gastroenteritis worldwide.

There’s an alarming outbreak causing concern among health officials in New Jersey, as norovirus has been spreading rapidly — and doctors say it is highly contagious.

Norovirus can survive on surfaces for weeks, and health officials say the virus can defeat most household cleaners. The Centers for Disease Control and Prevention recommends using a bleach solution that you dilute with water.

Minnesota hospitals are experiencing “unprecedented visits” due to a spike in illnesses, including influenza, RSV, COVID-19 and norovirus, according to the Minnesota Hospital Association.