Is Coronavirus Airborne? COVID-19 Survives In The Air, New Study Reveals

A new scientific study showing SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), the mutation that causes COVID-19, can remain alive while airborne for up to three hours is being questioned as misleading.

Another study published recently in the New England Journal of Medicine (NEJM), however, revealed the even more alarming discovery SARS-CoV-2 can remain alive on certain surfaces for up to nine hours. The study evaluated the stability of SARS-CoV-2 compared to SARS-CoV-1 (the most closely related human coronavirus) in aerosols such as droplets from a cough and on various surfaces and estimated their decay rates.

The 10 experimental conditions in the study involved both SARS-CoV-2 and SARS-CoV-1 in five environmental conditions -- aerosols, plastic, stainless steel, copper and cardboard.

The study showed SARS-CoV-2 remained viable in aerosols throughout the experiment of three hours, which means this virus remained contagious over that time period. It also revealed SARS-CoV-2 is more stable on plastic and stainless steel compared to copper and cardboard. This viable (or contagious) virus was detected up to 72 hours after application to plastic and stainless steel surfaces.

On copper, however, no viable SARS-CoV-2 was measured after four hours and no viable SARS-CoV-1 was measured after eight hours. On cardboard, no viable SARS-CoV-2 was measured after 24 hours. No viable SARS-CoV-1 was measured after eight hours.

The study said the half-lives of SARS-CoV-2 and SARS-CoV-1 were similar in aerosols for up to 1.1 to 1.2 hours. The half-lives of the two viruses were also similar on copper. On cardboard, the half-life of SARS-CoV-2 was longer than that of SARS-CoV-1.

On the other hand, the longest viability of both viruses was on stainless steel and plastic. The estimated median half-life of SARS-CoV-2 was 5.6 hours on stainless steel and 6.8 hours on plastic.

Robert Redfield, director of the U.S. Centers for Disease Control and Prevention (CDC), told Congress last month CDC was aggressively evaluating how long COVID-19 can survive on surfaces.

“On copper and steel, it’s pretty typical, it’s pretty much about two hours,” said Redfield. “But I will say on other surfaces -- cardboard or plastic -- it’s longer, and so we are looking at this.”

Redfield said infections contracted from surfaces rather than through the air could have contributed to the outbreak on the Diamond Princess cruise ship still quarantined in dock in Yokohama, Japan.

Experts say the risk of consumers becoming infected from touching these materials remains low. If people are concerned about the risk of contamination, they can clean packages with disinfectant and wash their hands.

“Everything at the grocery store and restaurant takeout containers and bags could in theory have infectious virus on them,” said Dr. Linsey Marr, who was not a member of the research team but is an expert in the transmission of viruses by aerosol. “We could go crazy discussing these ‘what-ifs’ because everyone is a potential source, so we have to focus on the biggest risks.”

The airborne survival of virus aerosols is even more contentious. An aerosol is any droplet smaller than 5 micrometers. SARS-CoV-2 can remain suspended in the air for about a half-hour -- but under laboratory conditions -- before drifting down and settling on surfaces where it can linger for hours.

The JAMA study that came to this conclusion was conducted in Singapore. To assess the ability of the virus to survive in the air, researchers developed what one expert described as “bizarre experiments done under very ideal controllable experimental conditions.” Researchers used a rotating drum to suspend the aerosols, and provided temperature and humidity levels closely simulating hospital (and not real world) conditions. Dr. Marr commented the experimental setup might be less comfortable for the virus than a real-life setting.

This ideal setup saw the virus survive and stay infectious for up to three hours. It also showed the ability of SARS-CoV-2 to infect fell sharply over this time. The aerosols might stay aloft for about 10 minutes but Dr. Marr said it could stay airborne for three times longer.