Presently the world is grappling with COVID-19. Worldwide, people are searching for effective ways to prevent the infection by SARS-CoV-2.
The CDC now has published guidelines for cleaning and disinfection of public spaces, workplaces, businesses, schools, and homes. Please review this regularly for updates or changes. As the country reopens for business, it is paramount to follow these guidelines to minimize and prevent infections by SARS-CoV-2.
Kampf et al. in February 2020 reported that human coronaviruses such as Severe Acute Respiratory Syndrome (SARS) coronavirus, Middle East Respiratory Syndrome (MERS) coronavirus or endemic human coronaviruses (HCoV) can persist on inanimate surfaces like metal, glass or plastic for up to 9 days.
However, they can be efficiently inactivated by surface disinfection procedures using 62 to 71% ethanol, 0.5% hydrogen peroxide or 0.1% sodium hypochlorite within 1 minute.
But other biocidal agents such as 0.05 to 0.2% benzalkonium chloride or 0.02% chlorhexidine digluconate are less effective.
A recent study of the stability of SARS-CoV-2 published on March 17, 2020, at NEJM.org studied how stable the virus is in aerosols and various other surfaces. The study found that the stability of SARS-CoV-2 was like SARS-CoV-1. The virus is stable in aerosols for hours and on surfaces up to days. Hence inactivation of the virus to prevent transmissions and infections is of paramount importance.
Another study published in April 2, 2020, in the Lancet measured the stability of SARS-CoV-2 in different environmental conditions. Infectious doses of the virus were incubated for up to 14 days and tested for its infectivity.
If not treated with destabilization agents such as soap or alcohol, the virus is highly stable at 4°C. However, the virus is sensitive to heat. Heat at 65 to 70°C inactivates the virus within 5 minutes.
After 3 hours, on printing and tissue, no infectious virus was detected in droplets containing contagious virus media when pipetted on a surface at 22°C and 65% humidity.
After two days, no infectious virus was detected on treated wood and cloth.
SARS-CoV-2 is more stable on smooth surfaces such as glass and banknotes (stable for three days), stainless steel, and plastic (stable for six days).
SARS-CoV-2 is also stable in the outer layer of a surgical mask for several days. Interestingly, after inactivation, an inactive virus could still be discovered.
(i) As a result of this study, SARS-CoV-2 is highly stable in favorable environments.
(ii) SARS-CoV-2 is susceptible to standard disinfection methods, hence unstable under these conditions.
Earlier, Darnell et al. reported that the treatment of SARS-CoV with ultraviolet light (UV) at 254 nm, with heat of 65 °C or greater inactivated the virus. Also, alkaline (pH > 12) or acidic (pH < 3) conditions, formalin, and glutaraldehyde inactivated the virus as well.
On April 06, Derraik et al. proposed a two-step disinfection process for the disinfection of personal protective equipment (PPE) as used by frontline medical and nursing staff to minimize the spread of the virus. This disinfection protocol relies on (i) storage of PPE for ≥4 days, followed by (ii) treatment with ultraviolet light (UVC), and (iii) a dry heat treatment, or chemical disinfection. The notion is that the use of different disinfection mechanisms maximizes the efficacy of the process.
The disinfection protocol starts with
(i) initial storage of PPE for ≥4 days,
(ii) followed by ultraviolet light (UVC) exposure, and
(iii) dry heat treatment, or a chemical disinfection step.
According to Keil et al., (published on April 20, 2020) in vero cell cultures, riboflavin and UV light also effectively inactivated SARS-CoV-2 by reducing the titer of SARS-CoV-2 in both plasma and platelet products to below the limit of detection. The data suggest that this process could be useful in reducing the theoretical risk of transfusion-transmitted SARS-CoV-2.
According to “Chemical & Engineering News (CEN) 2020-03-23.”
Respiratory viruses such as the new coronavirus SARS-CoV-2 are not very stable. Destruction of the viral lipid coating of the shell prevents infection by the virus.
Respiratory viruses such as the new coronavirus SARS-CoV-2 when expelled into the air by coughing, breathing or speaking can settle on surfaces. There they can linger in an active state for days, protected by mucus. Hence, if the mucus is destroyed, infection is prevented.
Presently, we are not exactly sure how long SARS-CoV-2 can remain active on a surface. One study done in a hospital found that similar coronaviruses can persist on hard surfaces like glass, metal, or plastic for up to 9 days.
SARS-CoV-2 remains stable on plastic and stainless steel for 2–3 days.
It is though that the virus can be spread to anyone touching the surface and to whatever that person touches next. Washing hands with soap and isinfecting surfaces regularly will prevent this.
Enveloped viruses like SARS-CoV-2, which rely on a protective lipid coating, are the easiest to deactivate.
To conclute. The shell of the virus can be destroyed as follows:
Alcohol-based products disintegrate protective lipids.
Quaternary ammonium disinfectants, commonly used in healthcare and food-service industries, attack protein and lipid structures, preventing the typical mode of infection.
Ethanol (78–95%),
2-propanol (70–100%),
the combination of 45% 2-propanol with 30% 1-propanol,
glutardialdehyde (0.5–2.5%),
formaldehyde (0.7–1%), and
povidone iodine (0.23–7.5%)
readily inactivates coronavirus infectivity.
Bleach and other potent oxidizers readily break down the virus's components.
Reference
CDC reopening guidance for cleaning and disinfecting public spaces, workplaces, businesses, schools, and homes.
Chemical & Engineering News (CEN) 2020-03-23.
Correspondence: Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1. N Engl J Med 2020; 382:1564-1567. DOI: 10.1056/NEJMc2004973.
Darnell ME, Subbarao K, Feinstone SM, Taylor DR. Inactivation of the coronavirus that induces severe acute respiratory syndrome, SARS-CoV. J Virol Methods. 2004 Oct;121(1):85-91. [ScienceDirect]
José G B Derraik, William A Anderson, Elisabeth A Connelly, Yvonne C Anderson; Rapid evidence summary on SARS-CoV-2 survivorship and disinfection, and a reusable PPE protocol using a double-hit process. medRxiv 2020.04.02.20051409. [Medrxiv]
How do we know disinfectants kill coronaviruses?
Kampf G, Todt D, Pfaender S, Steinmann E. Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents. J Hosp Infect. 2020 Mar;104(3):246-251. doi: 10.1016/j.jhin.2020.01.022. [PMC]
Shawn D. Keil, Izabela Ragan,Susan Yonemura,Lindsay Hartson, Nicole K. Dart, Richard Bowen; Inactivation of severe acute respiratory syndrome coronavirus 2 in plasma and platelet products using a riboflavin and ultraviolet light‐based photochemical treatment. First published: 20 April 2020 https://doi.org/10.1111/vox.12937 [PubMed] [Not peer reviewed]
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