NoroSTAT Data Table

The following table shows data on suspected and confirmed norovirus outbreaks reported to CDC by state health departments participating in the NoroSTAT network. States report through the National Outbreak Reporting System (NORS) and outbreaks are classified by week of illness onset, 2012-2024. The NoroSTAT network includes Alabama, Colorado, Massachusetts, Michigan, Minnesota, Nebraska, New Mexico, North Carolina, Ohio, Oregon, South Carolina, Tennessee, Virginia, Wisconsin, and Wyoming.* Data from the NoroSTAT network are typically released online on a monthly basis.

Norovirus Outbreaks Reported by State Health Departments by Week of Illness Onset, 2012–2024

Norovirus Outbreaks Reported by State Health Departments by Week of Illness Onset, 2012–2024
Week Minimum, 2012–20 Maximum, 2012–20 2020–21 Minimum, 2021–23 Maximum, 2021–23 2023–24
1-Aug 1 10 0 6 6 9
8-Aug 2 18 1 3 3 7
15-Aug 4 12 1 6 7 5
22-Aug 5 10 2 3 5 8
29-Aug 0 13 1 4 6 5
5-Sep 2 13 0 3 7 14
12-Sep 4 16 1 7 10 18
19-Sep 4 15 1 11 13 12
26-Sep 4 17 0 4 8 13
3-Oct 3 16 2 8 11 16
10-Oct 5 21 0 9 12 19
17-Oct 5 19 0 3 9 15
24-Oct 5 18 1 9 12 19
31-Oct 14 27 0 9 15 28
7-Nov 9 27 2 8 15 36
14-Nov 10 27 0 8 14 22
21-Nov 10 41 0 6 11 25
28-Nov 27 65 2 12 17 60
5-Dec 35 65 2 17 23 40
12-Dec 25 88 0 14 31 46
19-Dec 13 56 0 11 13 17
26-Dec 23 70 1 16 21 29
2-Jan 33 92 6 16 43 48
9-Jan 28 66 4 12 37 57
16-Jan 34 92 4 18 36 55
23-Jan 41 84 7 40 44 48
30-Jan 45 66 15 45 50 44
6-Feb 38 72 10 48 69 44
13-Feb 35 62 18 66 68
20-Feb 24 70 11 56 64
27-Feb 35 78 15 79 106
6-Mar 33 67 25 57 66
13-Mar 32 51 25 67 76
20-Mar 11 55 28 41 68
27-Mar 10 60 29 50 66
3-Apr 6 57 43 39 68
10-Apr 1 34 50 29 41
17-Apr 1 32 38 28 39
24-Apr 3 28 22 32 45
1-May 2 27 24 32 38
8-May 1 28 23 14 26
15-May 0 31 17 17 22
22-May 0 19 6 12 13
29-May 0 13 12 5 12
5-Jun 0 12 10 1 15
12-Jun 2 13 9 4 12
19-Jun 1 12 11 7 7
26-Jun 1 8 6 5 7
3-Jul 2 10 7 1 4
10-Jul 1 12 11 7 14
17-Jul 0 11 5 2 5
24-Jul 2 11 5 6 7

*Notes:

  • Michigan and South Carolina joined the NoroSTAT network at the start of the 2015-16 seasonal year; 2012-15 data from these states have been added for comparison.
  • Massachusetts and Virginia joined the NoroSTAT network at the start of the 2016-17 seasonal year; 2012-16 data from these states have been added for comparison.
  • New Mexico and Wyoming joined the NoroSTAT network at the start of the 2018-19 seasonal year; 2012-2018 data from these states have been added for comparison.
  • Nebraska joined the NoroSTAT network at the start of the 2019-20 seasonal year; 2012-2019 data from this state were added for comparison.
  • Alabama and North Carolina joined the NoroSTAT network at the start of the 2022-23 seasonal year; 2012-2022 data from these states have been added for comparison.
  • Colorado joined the NoroSTAT network at the start of the 2023-24 seasonal year; 2012-2023 data from this state were added for comparison.