The National Institute of Health released a pre-publication report March 11th on environmental stability of the virus causing COVID-19 illnesses. This was based on lab work conducted in the U.S. with the new virus. They examined survival in aerosol form in the air (such as after a sneeze or cough), and on cardboard, copper, stainless steel, and polypropylene (plastic) surfaces. The authors compared survival of the new virus to the coronavirus that caused the SARS outbreak in 2002-03 by testing both in this study.
“…viable virus could be detected in aerosols up to 3 hours post aerosolization, up to 4 hours on copper, up to 24 hours on cardboard and up to 2-3 days on plastic and stainless steel”
The half-life in aerosol for the virus averaged 2.7 hours. The half-life on stainless steel averaged 13 hours, and was 16 hours on polypropylene. This means that is how long it took for the initial levels to drop by 50%. The test was conducted at 40% RH and 72-73 °F (representative of indoor conditions). Overall, the survival rate of the COVID-19 virus was very similar to the coronavirus that caused the SARS outbreak in 2002-03.
What does this mean?
-The SARS virus and the new COVID-19 virus are very similar in their ability to persist in the environment, yet COVID-19 has spread worldwide while SARS was predominantly a regional outbreak. SARS spread primarily in healthcare settings, while COVID-19 is spreading there and in the general population. Given these new findings regarding surface survival, the rapid spread of the COVID-19 illness cannot be attributed to greater persistence in the environment than other coronavirus strains. The current thinking remains that the predominant mode of transmission is due to respiratory droplets in person-to-person interactions. These aerosolized droplets can be inhaled or spread via direct contact with an infected person. This new virus is proving to be more contagious (easier to contract) than the SARS or MERS coronavirus strains. The reason for this is currently not known. This NIH study reveals that the novel coronavirus is similar to other coronavirus strains in its survival on surfaces.
-The NIH study determined how long the coronavirus could be detected from various surfaces under the specific environmental conditions of the trial. This study did not determine at what point the virus dropped below an infectious level on the surfaces. Health experts have noted that the virus dies off over time outside a host, and even if present, is unlikely to be capable of causing infection for prolonged periods outside of a human or animal host.
-These findings are part of the overall picture as to why more significant action is being taken to increase social distancing measures in communities. An infected person will shed the virus in coughs and sneezes, and the tiny respiratory droplets expelled carry significant levels of virus that can be inhaled or get directly into the eye. Social distancing is being implemented to reduce this person-to-person spread in public areas.
-Frequent handwashing and good hygiene practices minimize risks from surface contaminants. The World Health Organization reported that the single most effective intervention in preventing hospital staff from becoming ill in the SARS coronavirus outbreak earlier this century was increased access to and use of handwashing stations by hospital staff. Since we can’t tell by looking at a surface if there is a virus present, washing our hands is our best line of defense.
-Cleaning and disinfecting surfaces is an additional step we can take to fight the virus. Be sure to clean any visibly dirty surface prior to disinfection, and use EPA registered disinfectants according to their label for efficacy against coronavirus / emerging viral pathogen COVID-19.
Frank Kelsey helps growers, packers and processors of fresh fruit and vegetable products address food safety and shelf-life extension challenges. He has multiple publications in the area of produce safety research and has been an invited speaker at numerous industry technical conferences. He is trained on virus prevention in food processing by the International Association for Food Protection. He is the Chief Science Officer at Highland Ag Solutions.