Norovirus cases have surged across the United States, with 91 infections reported in a single week this December, according to the U.S. Centers for Disease Control and Prevention (CDC). This figure is more than double the highest weekly count recorded in the last three years.

The spike reflects trends in Minnesota, a state where local health officials reported double the normal number of cases in December.

Often known as the stomach flu, norovirus is the leading cause of gastroenteritis, an inflammation of the stomach and intestines associated with vomiting and diarrhea.

According to the CDC, norovirus is responsible for 58% of foodborne illnesses in the U.S., with outbreaks most commonly occurring in schools, healthcare facilities, and restaurants.

In India, 70–85% of norovirus-associated diarrhea in children is caused by group II (GII) noroviruses.

It is a contagious stomach and intestinal virus that can spread through contaminated food, water, or direct person-to-person contact.

Why don’t alcohol sanitizers work against norovirus?

Unlike SARS-CoV-2, which is the virus responsible for COVID-19, norovirus is a non-enveloped virus. Its tough protein shell, or capsid, makes it resistant to pH and temperature changes, as well as to many disinfectants, including alcohol-based hand rubs or sanitizers.

Alcohol sanitizers, regardless of their concentration, cannot penetrate the capsid to inactivate the virus.

In contrast, viruses like SARS-CoV-2 have a fragile outer layer that alcohol can easily break down. This key difference has created confusion, especially since alcohol sanitizers have become a staple of hygiene during the COVID-19 pandemic.

Aaron Hall, a norovirus expert at the CDC, told NBC News that soap and water can wash away the virus, but only extremely hot water can kill it.

Scientific research has consistently shown that alcohol-based sanitizers are ineffective against norovirus, with 2011 studies confirming this limitation.

While alcohol-based sanitizers remain effective against many respiratory viruses, they are not a reliable defense against norovirus.

Health experts recommend proper hand washing with soap and water as well as using alternative disinfectants such as hypochlorous acid-based sanitizers. Despite these findings, many healthcare facilities continue to rely heavily on alcohol-based sanitizers, partly because of their convenience.

A survey of 161 long-term care facilities in the US showed that regular use of alcohol-based hand sanitizers did, in fact, increase the risk of spreading norovirus. However, the researchers highlighted that further studies are needed to confirm a direct causal link.

With norovirus infections on the rise, public health experts continue to emphasize the importance of washing hands thoroughly for at least 20 seconds with soap and warm water to limit the spread of this highly flexible pathogen.

Norovirus prevalence

Globally, norovirus causes an estimated 685 million cases of acute gastroenteritis annually, including 200 million infections in children. According to the CDC, it results in approximately 50,000 deaths and significant health care costs, estimated at $60 billion worldwide.

Unlike respiratory viruses that spread through airborne particles, norovirus is typically spread through infected fecal matter, vomit, contaminated food, or direct contact with surfaces.

Symptoms include vomiting, diarrhea, stomach cramps, less urination or dark urine, weakness, dry mouth, mild fever, muscle pain, and headache.

Norovirus can survive on surfaces for up to four weeks, making it highly contagious.