January through March is famous for adverse weather conditions across much of the Northern Hemisphere. But a new study from TraceOne has shown these months to also be rather infamous for their high rates of illness, specifically norovirus. The analysis of the CDC NORS data on norovirus outbreaks found that norovirus activity consistently begins rising in December, is highly elevated through the winter, then gradually declines as the spring months set in, with historic lows in mid-summer.
As theorized in the report, the highs of winter align with public health observations that gastrointestinal illnesses tend to rise in the winter, when people are indoors in closer proximity and shared spaces and group activities increase exposure risk. Other findings of the study were that norovirus outbreaks were most common in long-term facilities (e.g., nursing homes and assisted living facilities) where residents generally stay indoors and have weaker immune systems, with the next most common sites being schools (from pre-K to university) and restaurants/foodservice. Such findings seem to back up the assessment that close quarters, shared surfaces, or group dining contribute to rapid transmission.
However, neither the cold weather nor the close quarters rationale follow for the somewhat random outbreak rates reported from state to state, with Wisconsin and Illinois showing the highest rates of norovirus, with Minnesota, Virginia and Ohio also showing higher rates, but South Dakota among the lowest. The report notes that the rural/less dense population of South Dakota (along with Oklahoma and Arkansas also with the fewest outbreaks) could be one reason for the variance, as could underreporting, limited public health capacity, or different surveillance priorities may also contribute to these lower figures.
Regardless of the particular state numbers or rationale, however, the study’s finding that January through March accounted for more than half of all reported norovirus outbreaks during the 10-year period studied begs the question to food businesses: Are you prepared?
As discussed in TAG’s Public Health Fact Sheet on Norovirus, there are 4 main steps for prevention and protection against norovirus in the workplace:
- Recognize and manage the signs/symptoms, and potential source.
- Implement valid preventive strategies.
- Verify that practices are in place and being followed consistently.
- Respond as needed to identified lapses in any protocols.
For more information on Norovirus and detail on each of the 4 steps, see the Norovirus Fact Sheet.
Public Health News:
- The US Department of Health and Human Services plans to shrink the overall number of recommended vaccines for children in 2026. Early reports indicate that they may recommend following what is done in Denmark, where routine vaccines for RSV, rotavirus, Chicken Pox, hepatitis B (at birth), hepatitis A, influenza, or meningococcal disease are not given. Medical professionals are worried about possible impacts given the differences in universal health care options between the 2 countries.
- A population based study has identified several occupational risk factors related to long COVID. The study identified several non–work-related factors associated with higher long-COVID risk, including female sex, obesity, multiple underlying conditions, and more severe or repeated infections. Workers in jobs with higher likelihood of COVID exposure had a 44% higher likelihood of developing long COVID than those in low-risk occupations, including working onsite vs teleworking, inconsistent use of high filtration respirators, and use of public transportation for commuting.
- More than 2,000 cases of West Nile virus were reported in the US in 2025, an increase of about 10% over 2024, likely due to climate change. States reporting the highest numbers of cases in 2025 include Colorado (284), Illinois (137), Texas (115), and Minnesota (112).
