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Disinfectant Efficacy Against New Variants of SARS-CoV-2, the Virus that Causes COVID-19
In the last few months, it’s emerged that a number of variants of SARS-CoV-2, the virus that causes COVID-19, are circulating globally. Variants arise through a process called mutation where the virus undergoes changes to its genetic structure. The new variants can have characteristics that are different from the original virus. You may see the terms “variant” and “strain” used interchangeably, and in this context, they mean the same thing.
Currently there are three variants of note: one that emerged in the UK in September 2020 and has now been detected in the US, one from South Africa that was first reported in October 2020, and one from Nigeria that emerged at the end of 2020. The UK and South Africa variants appear to spread more rapidly than the original SARS-CoV-2 virus, but do not appear to cause more severe disease and can still be detected by currently available viral tests.
In January 2021, the United States Environmental Protection Agency (EPA) issued a statement saying that it expects disinfectants on List N Disinfectants for Coronavirus (COVID-19) to kill all strains of SARS-CoV-2. This is to be expected based on the structure of viruses. Let’s take a look and see why.
Viruses can be split into three classes. Enveloped viruses, large non-enveloped viruses, and small non-enveloped viruses. An enveloped virus is surrounded by a fatty layer which breaks apart very easily making the virus very easy to kill with disinfectants. Non-enveloped viruses have a tough outer coating making them much harder to kill with disinfectants.
SARS-CoV-2 is an enveloped virus but also contains protein “spikes” that stick through the fatty outer layer, creating a “crown”-like structure — one that you’re no doubt familiar with.
The key point is this: the variant resulting from a mutation in an enveloped virus is still an enveloped virus with the easy to penetrate fatty layer, and therefore equally susceptible to disinfectants as the original. The mutation may slightly change the make-up or characteristics of individual parts, such as the protein spikes, but it does not change the physical structure of the virus. This scientific rationale is the basis for the EPA’s determination that viruses on List N are expected to kill all strains, or variants, of SARS-CoV-2.
Disinfectant antiviral efficacy in practice
In practice, we can see the fact that different strains or variants of viruses are equally easy to kill when we look at kill claims (or contact times) for influenza A viruses on product labels. There are many variants of this virus including H5N1, H1N1, H3N2. However, when the microorganism claims on a product label include more than one variant of this virus, the kill time (or contact time) is always the same for all variants. The EPA recognized this in 2009 when there was an outbreak of a new strain of influenza A, H1N1. At that time, the EPA ruled that any disinfectant that killed a known strain of influenza A would also be effective against the new strain.
Many disinfectants can kill SARS-CoV-2 with contact times ranging from 15 seconds to 2 minutes. As EPA suggests, we can expect that List N disinfectants will be effective against all variants of SARS-CoV-2 including the current ones from the UK, South Africa and Nigeria.
For the latest information on COVID-19 and variants, visit our CloroxPro COVID-19 Hub.