Top 5 Takeaways

  1. Decline and Resurgence: The incidence of norovirus outbreaks in the United States significantly declined in April 2020, likely due to COVID-19 nonpharmaceutical interventions. However, outbreaks increased rapidly from January 2022, approaching pre-pandemic levels.
  2. NoroSTAT Network: Established in 2012, NoroSTAT, a collaboration between CDC and 12 state health departments, enhances the surveillance for norovirus outbreaks in the U.S.
  3. 2021-2022 Data: During the 2021-2022 surveillance year, the 12 NoroSTAT-participating states reported 992 norovirus outbreaks, a substantial increase compared to 343 in the 2020-2021 year.
  4. Outbreak Characteristics: Most outbreaks (82%) were due to person-to-person spread, primarily in long-term care facilities. The GII.4 Sydney(P16) strain continued to be predominant.
  5. Prevention Measures: Proper hygiene, such as thorough handwashing and avoiding food preparation until 48 hours after symptoms end, are key to preventing norovirus transmission.

Original Article Author and Citation

Corresponding Author

Anita K. Kambhampati,

Suggested Citation

Kambhampati AK, Wikswo ME, Barclay L, Vinjé J, Mirza SA. Notes from the Field: Norovirus Outbreaks Reported Through NoroSTAT — 12 States, August 2012–July 2022. MMWR Morb Mortal Wkly Rep 2022;71:1222–1224. DOI:


Norovirus is a leading cause of acute gastroenteritis in the United States. The Norovirus Sentinel Testing and Tracking Network (NoroSTAT), a collaboration between the CDC and 12 state health departments, was established to improve surveillance for norovirus outbreaks. NoroSTAT-participating states report confirmed and suspected outbreaks, contributing to a more comprehensive understanding of norovirus transmission patterns.


NoroSTAT-participating states are required to report norovirus outbreaks within 7 business days of notification. They also upload typing information for norovirus-positive outbreak specimens to CaliciNet. Surveillance years are organized from August 1 to July 31, aligning with the state funding cycle.


The notable decrease in norovirus outbreaks in 2020 coincides with the implementation of COVID-19 prevention measures. However, the relaxation of these measures has led to a resurgence in norovirus outbreaks, highlighting the effectiveness of nonpharmaceutical interventions in controlling infectious diseases.


The study underscores the importance of continued vigilance in hygiene practices to prevent norovirus outbreaks. The findings also suggest that public health measures effective against COVID-19 can have a broader impact on preventing other infectious diseases.


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