The COVID-19 Coronavirus Remains Viable for Hours or Days on Solid Surfaces

A recently published paper sheds light on how coronavirus spreads through the air and how long it remains viable on various solid surfaces.

A novel coronavirus of zoonotic origin, SARS-CoV-2 (2019-nCoV) was first identified in patients with acute respiratory disease (COVID-19). This virus is genetically similar to SARS coronavirus and bat SARS-like coronaviruses. The outbreak was initially detected in Wuhan, a major city of China, but has subsequently exploded into a pandemic, which is raging in most of the countries of the world. At this time more than 425,000 cases of the disease have been confirmed with thousands of fatalities. Signs of infection are highly non-specific and these include respiratory symptoms, fever, cough, dyspnea, and viral pneumonia. The elderly and those with chronic diseases seem to suffer a more severe disease than does the younger, healthier population.

Many questions remain unanswered regarding how coronavirus spreads. To answer some of them, investigators at the University of California, Los Angeles (USA), the [U.S.] National Institute of Allergy and Infectious Diseases (Bethesda, MD, USA), the [U.S.] Centers for Disease Control and Prevention (Atlanta, GA, USA), and Princeton University (Princeton, NJ, USA) analyzed the aerosol and surface stability of SARS-CoV-2 and compared it with SARS-CoV-1, the most closely related human coronavirus.

For the study, aerosols similar to those observed in samples obtained from the upper and lower respiratory tract in humans, containing SARS-CoV-2 or SARS-CoV-1 were generated with the use of a three-jet Collison nebulizer. In addition, the viability of the viruses was determined in four environmental conditions (plastic, stainless steel, copper, and cardboard).

Results revealed that SARS-CoV-2 remained viable in aerosols throughout the duration of the three hour experiment, but with a small reduction in infectious titer. This reduction was similar to that observed with SARS-CoV-1.

SARS-CoV-2 was more stable on plastic and stainless steel than on copper and cardboard, and viable virus was detected up to 72 hours after application to these surfaces, although the virus titer was greatly reduced. Significant reduction in virus titers were noted after 72 hours on plastic, after 48 hours on stainless steel, 24 hours on cardboard, and only four hours on copper. The stability kinetics of SARS-CoV-1 were similar. This suggests that differences in the epidemiologic characteristics of these viruses probably arise from other factors, including high viral loads in the upper respiratory tract and the potential for persons infected with SARS-CoV-2 to shed and transmit the virus while asymptomatic.

While the results indicated that viable viruses could be detected for hours or days on some surfaces, it was not shown whether these viruses were still capable of causing the disease.

Contributing author Dr. James Lloyd-Smith, professor of ecology and evolutionary biology at the University of California, Los Angeles, said, "This virus is quite transmissible through relatively casual contact, making this pathogen very hard to contain. If you are touching items that someone else has recently handled, be aware they could be contaminated and wash your hands. The biology and epidemiology of the virus make infection extremely difficult to detect in its early stages because the majority of cases show no symptoms for five days or longer after exposure. Many people will not have developed symptoms yet."

The report appeared in the March 17, 2020, online edition of the journal New England Journal of Medicine.

Related Links:
University of California, Los Angeles
[U.S.] National Institute of Allergy and Infectious Diseases
Centers for Disease Control and Prevention
Princeton University