Illinois had at least 103 outbreaks of the stomach bug norovirus in November and December — a dramatic increase from previous years, according to the Illinois Department of Public Health.

During the same time last winter, there were 22 reported outbreaks. This year’s numbers are also significantly higher than in winters before the pandemic, with 57 outbreaks in November and December of 2019, and 73 during that time frame in 2018, according to the state health department.

While it’s typical for norovirus cases to increase between November and April each year, “We are seeing a more significant rise in infections earlier in the season than usual,” according to the state health department.

The state does not track individual cases of the illness, just outbreaks, which consist of multiple cases.

The highly contagious illness can cause vomiting and diarrhea but is usually short-lived. Most people feel better within one to three days, according to the Centers for Disease Control and Prevention. Most people do not require hospitalization for norovirus, said Dr. Julie Holland, vice president for pediatric primary care at Advocate Children’s Hospital.

“It is very normal to see a bump of it in the winter, and we’re seeing more of it this year,” Holland said. “We’re not overwhelmed in the hospitals, but we’re definitely seeing a bump.”

It’s possible, however, the numbers might be starting to lessen.

So far, the state has recorded 10 outbreaks in January, though there can be delays in reporting outbreaks, according to the state health department.

Also, across the state, the number of weekly visits to emergency departments because of gastrointestinal illnesses — which can include norovirus — has dropped since late December.

The November and December jump was in line with national figures that also showed higher numbers of norovirus outbreaks this winter, compared with previous years. The CDC reported 91 suspected or confirmed outbreaks of norovirus across 14 states (not including Illinois) for the week that ended Dec. 5, compared with a maximum of 41 outbreaks for that week in other recent years.

Meanwhile, respiratory illness activity seems to be moderating in Illinois, after reaching high levels earlier this month. Statewide, hospital admissions due to flu, COVID-19 and RSV, or respiratory syncytial virus, are trending downward, according to the state health department.

Test positivity for COVID-19 and RSV were also down for the week that ended Jan. 11.

In Chicago, flu levels remain high, but COVID-19 and RSV activity have decreased, according to the Chicago Department of Public Health.

Doctors say it’s not too late for people to get flu and COVID-19 vaccines, if they haven’t already.

RSV vaccine is available for pregnant women and adults ages 75 and older, or those ages 60 to 74 who are at increased risk of RSV. Infants can receive an RSV antibody if their mothers didn’t get vaccinated during pregnancy.

No vaccine for norovirus is currently available. Norovirus can be spread by sharing food, eating food handled by others with the virus or by touching contaminated surfaces or objects and then putting one’s hands in one’s mouth.

The CDC recommends washing hands with soap and water for at least 20 seconds, especially before eating, preparing or handling food and after going to the bathroom. Hand sanitizer does not work well against norovirus.