St. Louis health officials issued a health advisory Thursday, warning that flu cases are surging in the city. It mirrors a national trend as doctor visits for flu symptoms throughout the United States have reached their highest level in decades.
The St. Louis Department of Health said cases of flu and influenza-like illness have risen steadily over the past month. The most recent data, from the week ending Dec. 27, shows the percentage of emergency room visits for respiratory illnesses in the city is at its highest level of the season.
“We're higher than last year, but it's typical for the flu seasons to start creeping up at this time of year,” said St. Louis Health Commissioner Victoria Anwuri, who added that flu activity usually peaks around the end of January.
Anwuri said it isn’t too late to get the flu vaccine.
"In fact, it's the perfect time to get the vaccine, because the peak of the season is going to be here in about three to four weeks,” she said. “If you get the vaccine today, your body will have two weeks to build up immunity, and you'll be more immune at the height of the season.”
The trend extends across Missouri. The state Department of Health and Senior Services said nearly 9,000 new influenza cases were reported in the last week of 2025 and more than 11% of emergency room visits during the week ending Dec. 27 were due to the flu.
Cases of flu and other respiratory illnesses typically increase around the holidays as people gather indoors. However, officials at the federal Centers for Disease Control and Prevention say this flu season has been particularly severe. The CDC reports 8.2% of outpatient doctor visits nationwide were patients who reported influenza-like illnesses. That’s the highest level since the CDC began tracking the data in 1997.
In Illinois, the Department of Public Health reported “very high” levels of flu activity this week, which is the most severe of five categories of respiratory illness activity. Health officials are especially concerned about low vaccination rates in the state; they say just 25% of Illinois residents had received a flu vaccine as of the end of December.
“Illinois is facing a significant winter surge in seasonal respiratory illnesses with flu activity at very high levels,” said Dr. Sameer Vohra, director of the department. “Vaccinations remain the most effective tool to prevent severe illness from flu, COVID-19 and RSV."
Each year, world health officials select flu strains for the seasonal vaccine based on the viruses circulating at the time. However, the virus can change between vaccine production and when people receive the shot.
Researchers have said this year’s vaccine may be mismatched with the dominant circulating strain, known as subclade K. Even so, scientists and public health officials say that immunizations can still keep people from getting dangerously sick, and that it’s not too late to get vaccinated.
