How Long Does Omicron Last on Surfaces and Does Disinfectant Kill It?

The Omicron variant may survive for a longer time on surfaces than other variants of COVID, according to a study.

Researchers in Japan examined how well samples of different COVID variants survived on either plastic or human skin obtained from autopsy specimens. The variants investigated in the study were the original Wuhan strain, as well as the Alpha, Beta, Gamma, Delta, and Omicron variants, which have been designated as variants of concern.

The study's authors argue that Omicron's stability may partly explain why it has spread so quickly, leading COVID cases around the world to spike to unprecedented numbers in recent months.

However, air continues to be the primary way COVID is spread. The Environmental Protection Agency, for instance, states on its website that the spread of COVID may "sometimes occur through contact with contaminated surfaces, though this route is now considered less likely."

Several months into the pandemic, experts argued that the focus should be shifted away from surfaces and onto the air, since this was identified as the main way that the virus is spread.

How well Omicron survives on surfaces compared to past variants

In the study, the sample of each variant was placed on the two surfaces and then left alone. The study also investigated the effectiveness of disinfectants against the virus samples.

The study was submitted to the pre-print server bioRxiv on January 19, and has therefore not been through the rigorous peer review process required by scientific journals.

The researchers found that on both plastic and skin, the Alpha, Beta, Delta, and Omicron variants all survived twice as long as the Wuhan, and remained infectious for more than 16 hours on skin.

Omicron in particular was the most stable of the variants studied. On a plastic surface, it survived for as long as 193.5 hours. The next highest was the Alpha variant at 191.3 hours, while the Wuhan strain lasted just 56 hours.

On skin, Omicron lasted 21.1 hours, while Alpha survived for 19.6 hours and the Wuhan strain for 8.6 hours.

Omicron also appeared to be slightly more resistant to alcohol-based disinfectant than the other variants in vitro (in a test tube or culture dish), however a 40 percent ethanol disinfectant was capable of completely inactivating it within 15 seconds. Other variants needed only 35 percent ethanol disinfectant to achieve the same inactivation time.

"This study showed that the Omicron variant also has the highest environmental stability among VOCs [variants of concern], which suggests that this high stability might also be one of the factors that have allowed the Omicron variant to replace the Delta variant and spread rapidly," the study concluded.

The study also recommended that people practice hand hygiene with sufficiently strong disinfectant. The U.S. Centers for Disease Control and Prevention (CDC), for instance, recommends use of hand sanitizer that contains at least 60 percent alcohol.

Writing The Conversation, Hassan Vally, associate professor of epidemiology at Deakin University in Australia, called the findings "interesting" but said the study's limitations mean it is difficult to know their real-world significance.

Vally said the study was limited by a lack of a clear rationale for the amount of virus deposited to the surfaces, and the fact that it was was carried out under highly-controlled lab conditions rather than real-world conditions.

"These results don't prove that we're at increased risk of picking up the Omicron variant from surfaces," Valley said. "But what it does do is confirm that wiping down surfaces and hand sanitising with disinfectants are effective methods of killing any live virus that may be lurking there."

Commenting on the findings, Dr. Amesh Adalja, adjunct assistant professor at the Johns Hopkins Bloomberg School of Public Health, told Medical News Today: "Even if the Omicron and Delta variants have more environmental stability than prior versions of SARS-CoV-2, surface transmission still plays a relatively minor role in the transmission of this virus."

Based on existing data, the U.S. Centers for Disease Control and Prevention (CDC) states that the virus that causes COVID tends to last on non-porous surfaces like stainless steel, plastic and glass for longer than on porous surfaces.

"Data from surface survival studies indicate that a 99% reduction in infectious SARS-CoV-2 [the COVID virus] and other coronaviruses can be expected under typical indoor environmental conditions within 3 days (72 hours) on common non-porous surfaces like stainless steel, plastic, and glass," the CDC states.

Hand sanitizer
A stock photo shows a person using hand sanitizer and wearing a face mask. Omicron may survive on surfaces longer than other variants, a study has suggested. Drazen Zigic/Getty