The Norovirus Tracker

Is norovirus going around in your state?

WastewaterSCAN rates norovirus at each treatment plant it samples. Of the 143 plants in 40 states sampled in the three weeks to October 9, 2026, 23 were rated high, 39 medium and 81 low. States with at least one plant rated high: Alabama, Alaska, Arkansas, California, Florida, Georgia, Hawaii, Idaho, Indiana, Louisiana, Maine, Maryland, Massachusetts, Michigan, Mississippi, Nebraska, Texas, Vermont.

A plant covers one city or county, not a whole state, and many states have only one or two plants in the network. Tap a state to see its plants. States not listed have no plant in the network or none sampled recently.

Ratings are WastewaterSCAN’s own: each plant’s level against its past year, plus a 21-day trend test. Every plant is on their map at data.wastewaterscan.org.

This season against the last two

The CDC says norovirus outbreaks are most common from November to April. In wastewater, the 2024-25 season was the bigger of the last two, peaking in the week ending January 4, 2025. Last season peaked later, in the week ending February 21, 2026, at about 38% of that height.

Outbreaks reported to the CDC

The CDC’s NoroSTAT network counts norovirus outbreaks reported by 12 states. They reported 27 outbreaks for August 1–September 4, 2026, against 29 in the same period last season. In the CDC’s words, this season is so far “within the middle 50% of outbreaks (interquartile range) reported in the same period during the 2012–2026 seasonal years.”

Peaks as the CDC published them at the end of each season. The number of reporting states changes between seasons, so compare shapes rather than exact totals.

Which states report the most norovirus outbreaks?

In the CDC’s National Outbreak Reporting System for 2014 to 2023, Rhode Island reported the most norovirus outbreaks for its size: 61.2 a year for every million residents. The top ten:

1. Rhode Island61.2
2. Wisconsin29.5
3. Minnesota24.0
4. Oregon20.5
5. Maine17.8
6. Virginia17.5
7. Nebraska16.7
8. Colorado16.6
9. Massachusetts16.5
10. Wyoming16.3

Read it as a map of reporting more than a map of illness. The CDC counts the outbreaks that state health departments find and send in, and some states look for far more than others. Over the same ten years, these states reported fewer than 15 norovirus outbreaks in total: Alaska (14), Arkansas (10), South Dakota (3), Oklahoma (6), New Jersey (9).

Outbreaks per million residents per year, on Census Bureau 2020 population estimates. Outbreaks that span more than one state are left out. Source: CDC NORS.

Which strain is going around

There are many kinds of norovirus, which is why the CDC says you can catch it many times in your life. Public-health labs in the CDC’s CaliciNet network type the virus behind confirmed outbreaks. The CDC notes that in years when there is a new strain of the virus, there can be 50% more norovirus illness.

Source: CDC CaliciNet, page updated October 9, 2026. CaliciNet shows which strains are circulating more reliably than how much illness there is.

Cruise ships

The CDC’s Vessel Sanitation Program has posted 9 gastrointestinal outbreaks on cruise ships in 2026 so far, 5 of them norovirus. By the same date last year it had posted 19; all of last year came to 23, 18 of them norovirus. The CDC posts an outbreak only when at least 3% of passengers or crew report gastrointestinal illness on a voyage it oversees, so the count moves with how many people sail as well as with the virus. The CDC says norovirus causes over 90% of diarrheal outbreaks on cruise ships, but cruise outbreaks are only a small percentage (1%) of all norovirus outbreaks.

Source: CDC Vessel Sanitation Program outbreak list, last updated July 23, 2026. Each ship links to the CDC’s notice.

Recalls and shellfish warnings

When norovirus shows up in a recall, it is almost always shellfish, usually raw or frozen oysters. The CDC advises cooking oysters and other shellfish thoroughly, to an internal temperature of at least 145°F. Recent federal actions:

Sources: FDA alerts and advisories list; FDA enforcement reports via openFDA (data through September 30, 2026). Recalls are regulatory actions, not a measure of risk. Our Gut Health Recall Tracker covers every gut-pathogen recall since 2019.

The bug itself, in the CDC’s words

• What it is. “Norovirus is a very contagious virus that causes vomiting and diarrhea. It is sometimes called the ‘stomach flu’ or the ‘stomach bug.’ However, norovirus illness is not related to the flu.” CDC
• How fast and how long. “A person usually develops symptoms 12 to 48 hours after being exposed to norovirus.” And: “Most people with norovirus illness get better within 1 to 3 days.” CDC
• How long it spreads. “You are most contagious when you have symptoms of norovirus illness or during the few days after you feel better.” But “studies have shown that you can still spread norovirus for 2 weeks or more after you feel better.” CDC
• Soap beats sanitizer. “Hand sanitizer does not work well against norovirus.” Soap and water “work to remove all types of germs from hands, while sanitizer acts by killing certain germs on the skin.” CDC
• Cleaning up. The CDC’s recipe for a disinfecting bleach solution is 5 to 25 tablespoons of household bleach (5% to 8%) per gallon of water, left on the surface for at least 5 minutes, or an EPA-registered disinfectant that works against norovirus. CDC
• How common. The CDC estimates norovirus causes 19 to 21 million illnesses in the United States each year, and about 2,500 reported outbreaks. Outbreaks “occur throughout the year but are most common from November to April.” CDC
• Where outbreaks happen. “Over half of all norovirus outbreaks reported in the United States occur in long-term care facilities.” CDC

If you are caring for someone who is sick, or you are unsure about dehydration, a clinician or pharmacist is the right person to ask.

Questions people ask

Is there a stomach bug going around right now?

As of October 9, 2026, WastewaterSCAN rated norovirus in US wastewater MEDIUM nationally. For the week ending October 3 the national level was 14% lower than the same week last year. CDC NoroSTAT states reported 27 outbreaks for August 1–September 4, 2026, against 29 in the same period last season. Norovirus outbreaks are most common from November to April, according to CDC.

When is norovirus season?

CDC says norovirus outbreaks occur throughout the year but are most common from November to April. In wastewater, the 2024-25 season peaked in the week ending January 4, 2025, and the smaller 2025-26 season in the week ending February 21, 2026, according to WastewaterSCAN data.

How long does norovirus last?

According to CDC, a person usually develops symptoms 12 to 48 hours after being exposed to norovirus, and most people get better within 1 to 3 days. The main symptoms are vomiting and diarrhea. This is educational information, not medical advice.

How long is norovirus contagious?

CDC says people are most contagious when they have symptoms and during the few days after they feel better, but studies have shown norovirus can still spread for 2 weeks or more after someone feels better. CDC advises people who are sick not to prepare or handle food or care for others until at least 2 days (48 hours) after symptoms stop, especially if they work in a restaurant, school, daycare or long-term care facility.

Is it a stomach bug or food poisoning?

It can be both. CDC calls norovirus the leading cause of vomiting and diarrhea, and of foodborne illness, in the United States. It is the virus people usually mean by the "stomach bug" or "stomach flu", although CDC notes it is not related to the flu, and you can get it from sick people and through contaminated food, water or surfaces. Other germs that cause food poisoning, such as Salmonella, E. coli and Listeria, are covered by food recalls, which this page lists for norovirus. This is educational information, not medical advice.

Does hand sanitizer kill norovirus?

Not well. CDC says hand sanitizer does not work well against norovirus and is not a substitute for handwashing, which is best. CDC explains that soap and water work to remove all types of germs from hands, while sanitizer acts by killing certain germs on the skin, and it names norovirus among the germs soap and water remove more effectively.

What strain of norovirus is going around?

In CDC CaliciNet data for September 1, 2025 – September 30, 2026, GII.4 Sydney[P16] caused 74 of 160 genotyped outbreaks (46.2%), the largest share. The season before, GII.17[P17] caused most outbreaks. CDC notes that in years when there is a new strain of the virus, there can be 50% more norovirus illness.

What states have the most norovirus right now?

In WastewaterSCAN’s plant-by-plant ratings for the three weeks to October 9, 2026, at least one treatment plant was rated high for norovirus in: Alabama, Alaska, Arkansas, California, Florida, Georgia, Hawaii, Idaho, Indiana, Louisiana, Maine, Maryland, Massachusetts, Michigan, Mississippi, Nebraska, Texas, Vermont. A plant covers one city or county, many states have only one or two plants in the network, and the full state table is on this page.

Has norovirus peaked yet this season?

Seasons usually build through the winter. In wastewater, the 2024-25 season peaked in the week ending January 4, 2025 and the 2025-26 season in the week ending February 21, 2026. As of October 9, 2026, WastewaterSCAN rates the national level medium. This page updates every week, so the peak shows up here as it happens.

Which states report the most norovirus outbreaks?

For their population, Rhode Island, Wisconsin, Minnesota, Oregon, Maine reported the most norovirus outbreaks to the CDC’s National Outbreak Reporting System from 2014 to 2023. That mostly reflects how hard each state health department looks: some states reported fewer than 15 norovirus outbreaks in ten years.

How we build this page

Every Monday we pull the latest public numbers, check several of them against what each agency’s own page shows, and update this page. We do not forecast, and we do not estimate cases. Wastewater levels show how much virus is moving through sewersheds, not how many people are sick; NoroSTAT counts outbreaks, not individual illness, in the states that take part; the cruise list only includes voyages the CDC oversees.

• NoroSTAT weekly outbreaks by season (CSV)
• Every CDC-listed cruise-ship GI outbreak since 1994 (CSV)
• FDA norovirus recalls since 2012 (CSV)
• Full method, sources and checks

Wastewater readings: WastewaterSCAN (data.wastewaterscan.org), shown here as WastewaterSCAN’s own ratings and our week-on-week and year-on-year comparisons; their data are licensed CC BY-NC 4.0 and are not included in our downloads. These data were collected as part of the WastewaterSCAN / SCAN project, a partnership between Stanford University, Emory University, and Verily funded philanthropically through a gift to Stanford University. Data citation: A. B. Boehm et al., Pathogen nucleic acids data in wastewater solids from 147 treatment plants in the United States: 2024-2025, Data in Brief, 2026.

Outbreaks, strains and cruise ships: CDC NoroSTAT, CDC CaliciNet and the CDC Vessel Sanitation Program. Recalls: FDA. Our CSVs are free to reuse under CC BY 4.0 with a link to this page.