It’s official: norovirus is back. Despite norovirus outbreaks being at historic lows during the COVID-19 pandemic, the virus, which is the #1 cause of foodborne illness in the United States, came surging back in the first quarter of 2022 with outbreaks peaking at nearly 80 per week in March.1 Norovirus is a particularly pesky virus for a variety of reasons, including:
- Persists on surfaces for weeks after a vomiting or diarrheal event
- Resists many formulations of sanitizers and disinfectants
- Difficult to study due to a lack of a culture system and reliance on surrogate viruses (like Feline Calicivirus), which don’t always behave like human norovirus
Since norovirus spreads easily via surfaces,2 proper and routine use of surface sanitizers and disinfectants that have efficacy against the virus is crucial. Despite this, few studies have evaluated the efficacy of various surface sanitizer chemistries against human norovirus (most have relied on surrogate viruses, like Feline Calicivirus, which have limitations.)3 Additionally, even less is known about the impact of the application method (spray vs. wipe) on virus removal. To fill these important knowledge gaps, scientists at GOJO recently collaborated with researchers at North Carolina State University.4 These researchers sought to:
- Evaluate the efficacy of four different classes of no-rinse food contact surface sanitizer chemistries (alcohol, quaternary ammonium compound, chlorine [in the form of bleach], and a lactic acid + surfactant blend).
- Evaluate and quantify the added benefit of virus removal from surfaces when wiping is used.
To perform this research, small strips (called “coupons”) of Formica® were prepared and inoculated with either human norovirus or Tulane Virus, a close relative to human norovirus that has been shown to be a good surrogate virus for human norovirus.3 Formica® was used as this material is commonly used in the construction of dining room tables found in restaurants. The research team then applied one of four surface sanitizers to the coupons and evaluated the level of virus inactivation. The researchers then repeated the experiments but used a controlled wiping apparatus to evaluate the impact of a paper towel wipe on removing the viruses from the coupons.
The study revealed several interesting findings. First, the various sanitizers used in the testing performed quite differently from one another. In fact, only the alcohol-based sanitizer significantly reduced the amount of virus on the coupons; the bleach-, quat-, and lactic acid-based products all had no impact on the amount of virus present on the coupon. While alcohol by itself has relatively little efficacy against norovirus, the total formulation (i.e., the active ingredients + non-active ingredients) clearly matters for the product’s efficacy. This has also been supported by previous research.5
Secondly, the researchers found that including a paper towel wiping step after applying the sanitizer significantly boosted the efficacy of all products, likely by the physical action of removal. The researchers also found a large amount of intact virus within the paper towels, supporting the theory of removal as a mechanism of action for this performance boost.
So, what do these research findings mean for those who purchase surface sanitizing products or run food safety programs at restaurants and other food establishments? Perhaps most importantly, this research reinforces the notion that not all surface sanitizers are equal. The well-formulated alcohol-based product clearly had superior efficacy over the other three products, including the quat- and chlorine-based products, which are used in most establishments. When choosing a product, make sure you are asking key questions, such as:
- Efficacy profile: Does the product kill the pathogens I am concerned about?
- Contact times: Does the product have reasonable contact times that are easy to comply with (e.g., 30 seconds or less)
- Safety profile: Does the product have any cautionary statements related to its routine use? Is mixing required with the product?
Finally, this research shows that while wiping can boost virus removal from a surface, the virus can remain on the paper towel or cloth used to wipe the surface. This highlights the importance of proper disposal of these materials after a vomit or diarrheal event, or whenever norovirus is suspected. Clean-up procedures need to be written in a way that treats these materials with extra care – for example, not allowing an employee to touch the paper towel or cloth with their bare hands. Failure to carefully handle these materials could result in unintended cross-contamination.
The research, which is publicly available, can be found on the Applied and Environmental Microbiology site.
To learn more about PURELL products for Foodservice, visit PURELL.com/Foodservice.