Dealing With Norovirus: A Q&A With Jeff Anderson, PhD.

by Jeff Anderson

1. What factors are contributing to the increased instances of norovirus outbreaks?
The number of norovirus outbreaks changes (goes up and down) from year to year and from season to season. There are a few factors that seem to contribute to increased instances of norovirus outbreaks. Outbreaks occur year round but the CDC surveillance data shows that outbreaks occur much more frequently in winter months (typically from November through March). The type of setting also is a factor and institutional settings (nursing homes, hospitals, schools, restaurants) where high numbers of individuals visit and interact with each other also experience increased instances of outbreaks. Another reason we may experience an unusually high outbreak season is when a new norovirus strains emerges and the population has not yet developed immunity to the new strain.


Norovirus Graph


What types of environments are most likely to see an outbreak and why?
Institutional settings, such as long-term care, healthcare, restaurants, schools, hotels and cruise ships, are the most common types of facilities associated with outbreaks. Given their nature, institutional settings simply have more opportunities for the virus to enter the facility on infected individuals, food and water, which can then be transmitted to high numbers of individuals via food, contaminated surfaces, contaminated water and through person-to-person interaction.

2. What preventive steps can facilities managers take to ensure that norovius does not strike their buildings?
Prevention and control strategies for buildings should include products, methods, and workplace reminders that help remove and/or deactivate norovirus on commonly contaminated surfaces, such as the hands of infected individuals and other environmental surfaces. Effective hand washing is likely the single most important method to prevent transmission of the virus. Facility managers should ensure that handwashing stations in restrooms and other areas have sinks with warm running water, soap, and a means to dry hands. Signage at handwashing stations can be used to remind people to wash hands and how to do so properly. Environmental disinfection of surfaces is another important control measure. Particular attention should be paid to disinfecting surfaces that have the highest risk of norovirus contamination such as bathroom surfaces and high-touch surfaces, such as railings, handles, buttons and door knobs. The CDC recommends either household chlorine bleach solutions or EPA-approved chemical disinfectants for surface disinfection ( Chemical disinfectants should be used according to their EPA-approved and labeled usage instructions. Steam cleaning (heat inactivation) at 158° F for five minutes or 212° F for one minute is often recommended for disinfecting soft furnishings and carpet that gets contaminated after diarrheal and/or vomitus events. Diarrhea and vomitus from norovirus infected individuals contain high concentrations of the virus so it’s critically important that quick, safe, and effective cleanup efforts are immediately implemented to prevent further transmission. 

What are some common misconceptions about norovirus and the procedures necessary to eradicate an outbreak?
A common misperception is that any disinfectant will deactivate novovirus. This is not the case. Noroviruses can be a challenging organism to deactivate, so only EPA-approved disinfectants that are registered for norovirus should be used to disinfect surfaces to help prevent and eradicate outbreaks. 

3. Are certain chemicals and equipment better than others when dealing with norovirus?
Yes. Only use household chlorine bleach solutions or EPA-approved disinfectants that are registered for norovirus and only use these according to their EPA-approved labeled usage instructions. 

4. Can one be “green” and still defeat norovirus?
Disinfectants cannot be certified and marketed as “green” per EPA regulations; however, many manufacturer’s of disinfectant products, like Procter and Gamble, design them to incorporate safety and sustainability.  

5. Is there a typical “norovirus season” similar to what we see with influenza?
Yes. “Norovirus season” occurs during the winter months. In the US, this season lasts from about November to the end of March (see graph above). 

6. Is special training and education necessary to beat norovirus, or will cleaning and disinfection best practices used to combat other bugs suffice?
It’s always best to thoroughly train facility sanitation workers and it is recommended that managers emphasize norovirus training immediately before and during the “norovirus season.” Training should emphasize the measures facility workers should take to enable proper handwashing, such as properly stocking handwashing stations and ensuring they are in working condition, as well as disinfection protocols for various high-risk surfaces.