When a new virus emerges, you might notice that cleaning products and air purifiers don’t list this specific pathogen on their labels. However, this does not necessarily mean those products are ineffective. In fact, EPA has a special process to help professionals evaluate effectiveness against new or “emerging” viruses, even if the product has not been specifically tested against them. While this guidance was developed and applies specifically to EPA-registered disinfectants, the principles and practices can be helpful in guiding responsible decision making during an outbreak.
EPA’s Emerging Pathogen Guidance Basics1
- EPA recognizes that it’s difficult to test every product against every possible virus, especially emerging strains.
- Instead, EPA suggests companies should proactively test effectiveness against “surrogate viruses”, well-studied viruses that are similar in structure or antimicrobial susceptibility to the potential emerging threats.
- If a product is proven effective against one or more surrogate viruses that are harder to kill than an emerging viral pathogen, it can reasonably be expected to work against the new virus as well.
Why Surrogate Viruses Matter
- Viruses are grouped by how tough they are to inactivate. Small, non-enveloped viruses (such as MS2 bacteriophage and Feline Calicivirus) are the hardest to inactivate, while enveloped viruses (Influenza A and avian flu) are easier.
- If a product is capable of inactivating hardier viruses, that activity can be used to infer effectiveness against emerging viral pathogens, even ones that are not listed on the label.
What this Means for Evaluating Products2
EPA’s process provides a framework for evaluating antiviral effectiveness in emerging pathogen situations.
For enveloped emerging viral pathogens:
Choose products proven to inactivate at least one large or one small non-enveloped virus, since these viruses are harder to kill than enveloped viruses.
For large, non-enveloped emerging viral pathogens:
The product should be effective against at least one small, non-enveloped virus, such as Feline Calicivirus or MS2, since small, non-enveloped viruses are harder to kill than larger ones because they are among the most resistant types.
For small, non-enveloped emerging viral pathogens:
The product should inactivate at least two small, non-enveloped viruses from different viral families, for example, Feline Calicivirus and MS2, to demonstrate broad-spectrum efficacy against the toughest viral types.
This approach enables informed decisions, even when the virus is emerging and not yet listed on product labels.
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