Which surface disinfectant is more effective against human norovirus on surfaces?

• A. Bleach
• B. Quaternary ammonium product
• C. Hydrogen peroxide
• D. Alcohol-based sanitizer

Answer: (A)

Norovirus is a hardy, non-enveloped virus, so it resists many disinfectants that work well on enveloped viruses. The best option for surface disinfection against this pathogen is sodium hypochlorite (bleach) used at proper strength and contact time. When diluted to an appropriate concentration to yield about 1000–5000 ppm free chlorine and kept wet on the surface for about one minute, bleach reliably inactivates norovirus and related particles. This strong oxidizing action directly disrupts the virus, making bleach the most consistently validated choice for surface disinfection in outbreaks or high-risk settings.

Quaternary ammonium products are generally not effective against non-enveloped viruses like norovirus, so they aren’t reliable for this purpose. Alcohol-based sanitizers do not reliably inactivate norovirus on surfaces, especially on nonporous or complex surfaces, and many hydrogen peroxide formulations require specific active ingredients and contact conditions to achieve the same level of assurance as bleach. Hence, bleach stands out as the most effective surface disinfectant here when used correctly.