Novel Coronavirus, COVID-19 and How to Deal with the Virus in the Indoor Environment: An Update


Ching-Yi Tsai, Ph.D. and Chin S. Yang, Ph.D.


A lot has happened since our last newsletter dealing with the disease COVID-19 caused by the

novel coronavirus SARS-CoV-2. This update provides additional information to help you deal with

the virus.


The Massachusetts Institute of Technology (MIT) reports that under the right conditions the virus containing droplets and gas clouds (aerosols) may travel up to 27 feet. These conditions are influenced by: gravity pull, wind direction and velocity, temperature fluctuations, relative humidity,

and the duration and intensity of sunlight (UV). Clearly the greater the distance between individuals and virus containing droplets or aerosols the less likely the chance of the virus infecting individuals, thus the importance of SOCIAL DISTANCING to decrease the risk and to reduce

spread of the virus.


There are more reports and evidences on asymptomatic or symptomless virus carriers among us.

This strengthens the importance of social distancing, handwashing and wearing a mask. Handwashing with hot water (caution: not too hot to burn skin) is even more effective than with

cold water. Using hot water cycle or adding bleach in your laundry can eradicate any possible viral

particles in the laundry. World Health Organization (WHO) website reports that SARS-CoV-2 virus

can be inactivated at 56°C (or 133°F) or higher, although it does not provide additional details, such

as moist heat.


Another issue being hotly debated is the use of mask by non-essential personnel, non-medical professionals and non COVID-19 patients. Different grades of masks have different filtration

efficiencies and protection. Respirators with filter cartridges may offer a very high degree of

protection if users are fit tested. N95 masks offer a very high degree of protection against viral

particles. Surgical masks and cloth masks may not offer as a high degree of protection as N95. At a

minimum, they create a barrier between our nasal openings and possibly contaminated air. If you

use a mask, make sure you change it, wash it and/or disinfect it regularly. Wash your hands with

soapy water before putting on the mask and after removing the mask. Obviously, we don’t want to

compete with the medical professionals for their supplies of N95 mask.


If an indoor space, whether it is a school, an office building, a supermarket, a food store, or a public building, is suspected to be exposed to a confirmed case or to a COVID-19 patient, sanitization or disinfection may be necessary. We suggest the followings:


1. Do not do any testing for the virus. It is unlikely you can find the testing anyway because all

the sampling and testing resources are used for medical purposes. Sampling and testing may take a few days. If it is contaminated, there is no time to waste on testing. Go ahead and plan for disinfection.

2. In additional to 60-70% alcohols, hydrogen peroxides, and diluted solutions of bleach or chlorine-releasing compounds. You can add heat or hot water at 60 °C (or 140°F) or higher into your arsenal for inactivation of SARS-CoV-2 virus. Hot water extractors used in carpet shampooing and cleaning can be used in such situations, provided 60°C hot water is used.


3. Consider using a combination of different disinfectants and different techniques of application. Fogging with hydrogen peroxides or diluted bleach solutions plus surface wiping with any of the four disinfectants. We want to emphasize the incompatibility of bleach solutions with other chemicals, including peroxides, alcohols, ammonia and ammonia-containing cleaners. So use them with the greatest caution.


4. Make sure there is sufficient contact time for the disinfection. In general, a 15 minutes contact is recommended for disinfections. In our previous newsletter, we suggest less than 15 minutes may be enough to inactivate SARS-CoV-2 virus, based on a review of SARS literature. A longer contact time will ensure proper disinfections.


5. Wipe surfaces where people are in frequent contact with diluted bleach solutions, wait for 15 minutes, then wipe with clean hot water, and finally dry the surfaces.


6. Post remediation/disinfection verification (PRV) can be achieved by taking surface swab samples and test them for bacteria and fungi as surrogates for the virus . A couple of reference samples from similar but non-impacted areas should be collected and analyzed for comparisons. Samples from disinfectant treated areas should have below detection or greatly reduced (>90% reduction) bacterial and fungal levels.


As always, know your disinfectants. Read instruction labels on the disinfectant containers or MSDSs, if they are available, before using them. These disinfectants should only be used and applied by professionals when used in large scales.


Our senior microbiologist, Dr. Ching-Yi Tsai, was a member of the Taiwanese team that identified

and completed whole genome sequences of SARS virus in patients in Taiwan. She helped to determine the replication and pathogenesis of SARS coronavirus. If you have any questions concerning the new coronavirus, SARS-CoV-2 or COVID-2019, you can reach her at 856-767- 8300 or Our effort to develop a RT-PCR method for the detection of the virus from the environment has been greatly delayed by the unavailability of some supplies and reagents. We do not believe the supplies and reagents will be available anytime soon due to government’s efforts to control the outbreak.


Scientific basics of SARS-CoV-2


COVID-19 is the pneumonia or disease caused by SARS-CoV-2 virus. SARS-CoV-2 belongs to a

large family of single-stranded RNA viruses. RNA is the genetic material of the virus. A structural

diagram of the virus is below for your reference. Coronaviruses are enveloped with a lipid layer

embedded with structural proteins. They use its spike glycoprotein (S) to bind its receptor, and

mediate membrane fusion and entry of virus RNA. Recently, researchers confirmed that SARSCoV-

2 uses human-angiotensin-converting enzyme 2 (hACE2) as the receptor to enter human cells through endocytosis. By denaturalizing proteins and disrupting its envelope using the disinfectants

discussed above, the virus cannot bind to the cell receptor and enter the human cells.





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Date: April 3, 2020