Twelve percent of nearly 3,000 norovirus tests during the week ending Nov. 22 came back positive — a notable increase from the 6.82% positivity rate three months earlier, according to CDC data.
During the week ending Aug. 23, 6.82% of 4,034 norovirus tests were positive. A CDC system that tracks viral activity in the U.S. shows a 12% positivity rate among 2,825 norovirus tests, as of Nov. 22, the most recent data available.
This near-double increase in percent positive norovirus tests is occurring at the same time activity for whooping cough and influenza is also increasing. Last December, the CDC’s viral activity dashboard recorded a 24.82% positivity rate in one week’s norovirus tests. The 2024-25 respiratory virus season acutely affected hospitals as infection rates of COVID-19, flu and respiratory syncytial virus rose while norovirus surged to a decade-high.
