The Omicron variant last for hours on plastic and skin surfaces but is easily disinfected

Posted on by Jesse Santiano, M.D.

How long does the Omicron variant stay alive on plastic surfaces and the skin? And what does it take to disinfect, and in what concentration?

Those are the questions answered in the study from the Kyoto Prefectural, University of Medicine. It came out yesterday and is a preprint available at medRxiv.

The authors tested the Wuhan strain, the first SARS-CoV-2 that came out, and the different SARS-CoV-2 variants, namely: Alpha, Beta, Gamma, Delta, and Omicron.

Virus samples were placed on plastic (polystyrene plate) and human skin (constructed skin model) surfaces (25°C, 77°F,  45–55% relative humidity) and evaluated how long they will last.

Survival times plastic surface 

The Alpha, Beta, Delta, and Omicron variants exhibited more than two-fold longer survival times than the Wuhan strain. I highlighted Omicron below since they are the most relevant for the current wave.  

  1. Wuhan strain – 56.0 h (95% confidence interval [CI], 39.0–76.7 h)
  2. Alpha variant – 191.3 h (95% CI, 152.5–232.1 h)
  3. Beta variant – 156.6 h (95% CI, 122.7–192.9 h)
  4. Gamma variant – 59.3 h (95% CI, 43.9–77.7 h)
  5. Delta variant – 114.0 hours (95% CI, 91.3–139.1 h)
  6. Omicron variant – 193.5 hours (95% CI, 153.1–236.2 h)

You can tell from the graph below that Omicron has the longest survival time. The lines in the middle of each bar represent the range of survival times in hours.

Source: Hirose et al., 2022

Survival times human skin surface

Omicron, Alpha, Beta, and Delta lasted twice as long as the Wuhan in the skin.  The Omicron variant  can stay alive for 21 hours and maintained infectivity for 16 hours on the skin. 

  1. Wuhan strain – 8.6 h (95% CI, 6.5–10.9 h)
  2. Alpha variant – 19.6 h (95% CI, 14.8–25.3 h)
  3. Beta variant – 19.1 h (95% CI, 13.9–25.3 h)
  4. Gamma variant – 11.0 h (95% CI, 8.1–14.7 h)
  5. Delta variant – 16.8 hours (95% CI, 13.1–21.1 h)
  6. Omicron variant – 21.1 hours (95% CI, 15.8–27.6 h)
Source: Hirose et al, 2022

 Disinfectant effectiveness in plastic

  • Wuhan strain and Gamma variants were completely inactivated within 15 seconds by 32.5% ethanol alcohol (logarithmic reduction > 4)
  • Alpha, Beta, and Delta variants were completely inactivated within 15 seconds by 35% ethanol alcohol
  • The Omicron variant was completely inactivated within 15 seconds by 40% EA.

Omicron required a slightly higher concentration of ethanol alcohol (40%)

Alpha, Beta, Delta, and Omicron variants were thus slightly more resistant to ethanol than the Wuhan strain. 

Disinfectant effectiveness on Human Skin

On human skin, 35% ethanol alcohol completely inactivated all viruses after exposure for 15 seconds.

The bar graph below compares the effectiveness of 70% isopropyl alcohol (IPA) (common rubbing alcohol) and the different concentrations of ethanol alcohol (EA) in reducing the amount of different SARS-CoV-2 strains.

Rubbing alcohol (70% isopropyl alcohol) can kill the different variants effectively. The Omicron variant needs a higher concentration of ethanol alcohol and should be at least 35% concentration compared to other variants.

Source: Hirose et al., 2022

In summary, this study shows that the Omicron variant lasts longer in plastic surfaces and the skin, thus contributing to its high transmission.

The WHO, FDA, and CDC recommend that ethanol alcohol in concentrations of more than 60% should be used for hand disinfection. Here is an FDA website that lists disinfectants you should NOT use.

 

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Related:

  1. How to Lower Viral Airborne Transmission Indoors
  2. Who, Where, and What can get you infected with COVID-19?
  3. How Far Can a Sneeze Go?
  4. Covid-19 Spread with Air-conditioning
  5. How Long does the Covid-19 Virus Float in the Air and Stay on Surface?
  6. Aerosol, and Surface Stability of SARS-CoV-2 Compared with SARS-CoV-1

 

References:

  1. Ryohei Hirose, Yoshito Itoh, Hiroshi Ikegaya, Hajime Miyazaki, Naoto Watanabe, Takuma Yoshida, Risa Bandou, Tomo Daidoji, Takaaki Nakaya. Differences in environmental stability among SARS-CoV-2 variants of concern: Omicron has higher stability.  bioRxiv 2022.01.18.476607; doi: https://doi.org/10.1101/2022.01.18.476607
  2. Golin AP, Choi D, Ghahary A. Hand sanitizers: A review of ingredients, mechanisms of
    action, modes of delivery, and efficacy against coronaviruses. American journal of infection control. 2020;48(9):1062-7.
  3. Infection prevention and control during health care when novel coronavirus (nCoV)
    infection is suspected. World Health Organization.: World Health Organization; 2020 [Available from: https://www.who.int/publications/i/item/10665-331495.

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