[EXPERT REACTION] COVID-19 Disinfection: Public places vs common user surfaces

Disinfection operations conducted by Housing and Local Government Minister (KPKT) through the Fire and Rescue Department -Twitter/KPKT

Many countries including Malaysia are disinfecting public areas such as schools, mosque, airports and road sides to curb the spread of COVID-19. This method has raised questions about its effectiveness. We asked experts this question:

Should we disinfect public places or target on common users surfaces?


Associate Professor Dr Chan Yoke Fun, Virologist, Department of Medical Microbiology, Faculty of Medicine, University of Malaya, said:

“I am not sure what disinfectant is used. Not all disinfectants have similar efficacy. Disinfectant works well only on clean surfaces, and therefore the surface must be cleaned first. The Environmental Protection Agency (EPA) USA has a list of disinfectant products approved for human Coronavirus claims for use against SARS-CoV-2. Targeted disinfection makes more sense, why disinfect places with no cases?

See the list by EPA for approved disinfectants. Recently, the Centers for Disease Control and Prevention (CDC) came out with guidelines for “Decontamination and Reuse of Filtering Facepiece Respirators using Contingency and Crisis Capacity Strategies”. I think some of this can be used for surfaces. 

I think this is a very informative guide for cleaning in non-healthcares setting. Read here.

Dr Khayriyyah Mohd Hanafiah, Microbiologist & Senior Lecturer at Medical Microbiology, Universiti Sains Malaysia, said:

“COVID-19 is known to be transmitted largely directly from an infected person, when they cough or speak and spread the virus to an uninfected person. Another less common but possible way is indirectly, when an infected person touches and transfers the virus to surfaces which then gets touched by someone else who then picks up food or touches their nose and face. Disinfectants such as sodium hypochlorite (bleach) and alcohol can inactivate the virus, but they are more suitable for surfaces that are regularly touched. 

Since everything requires a cost-benefit assessment, we must ask whether it is more cost-effective to do widespread disinfecting methods (which may be easier) or have more targeted disinfection, like public transport turnstiles, doorknobs, elevator handles (which may require more manual labor).”

Dr Thaigarajan Parumasivam, Senior Lecturer at School of Pharmaceutical Sciences, Universiti Sains Malaysia (USM), said:

“Spraying disinfectants along the roadside may not be an efficient approach to combat COVID-19. Though it has been proven COVID-19 transmission could happen via respiratory, no scientific evidence to justify spraying disinfectant in the air and on roads could reduce the transmission. On the other hand, it may lead to other issues, such as spraying will create chemical aerosols which can be deposited in the people’s lungs and lead to asthma or other respiratory problems. Spraying chemicals in the open-air possibly will pollute the environment especially, if it’s done on a larger scale and frequently. Perhaps the natural remedy from sunlight (UV rays) is sufficient to inactivate the viruses which omit the need for chemical disinfection. I firmly suggest the government to reconsider the approach of spraying chemicals in the air and on the roads as I don’t see a valid justification for doing so instead afraid it will create public anxiety. 

I feel it is better to disinfect high-touch surfaces, for instance, handrails, doorknobs, elevator buttons, toilet flushers and shopping carts. We also should encourage the use of natural ventilation. Crowded and contained places should be accommodated with enhanced ventilation and exhaust systems. In addition, the responsible parties should take extra precaution by providing hand sanitisers at their outlets (e.g. at shopping malls and places of worship) and accommodate the public toilets with a continuous supply of soaps and water.” 

Dr Fatimah Salim, Chemist & Senior Lecturer at the Centre of Foundation Studies, Universiti Teknologi MARA (UiTM), said:

“Outdoor public areas such roadside have less risk in comparison to indoor areas due to airflow and exposure to sunlight. These areas include bus stops, parks, open railway platforms, etc. Cleaning and disinfection efforts should be targeted to frequently-touched surfaces. To date, WHO suggests that the virus is mainly transmitted through contact with respiratory droplets rather than through the air. 

According to WHO, COVID-19 virus is primarily transmitted between people through respiratory droplets and contact routes (within 1 metre to close contact). The transmission can occur by direct and/or indirect contact in the immediate environment or with objects used on the infected person. In an analysis of 75,465 COVID-19 cases in China, airborne transmission was not reported. Airborne transmission is different from droplet transmission, which are generally considered to be particles <5μm in diameter, can remain in the air for long periods of time and be transmitted to others over distances greater than 1 metre. According to the US Cleaning and Disinfection SOP few things need to be considered before doing so. The detail should be referred here.

Focus on cleaning and disinfecting efforts shall be given to surfaces that are likely to be contaminated with pathogens and frequently-touched surfaces (e.g., door knobs, surfaces in and surrounding which possibly reached). Municipal councils could give more attention to public toilets, public transports, markets, lifts, and other locations which are essential during RMO. According to MOH recommendation, a minimum requirement of cleaning and disinfection at least once a day and more frequently if visibly soiled using standard hospital registered disinfectants, such as sodium hypochlorite 1000 ppm. 

Guidelines COVID-19 Management No.5/2020 update on 24 March 2020 (http://www.moh.gov.my/moh/resources/Penerbitan/Garis%20Panduan/COVID19/Annex_8_IPC_21032020.pdf)

Bionotes of experts

Associate Professor Dr Chan Yoke Fun is a virologist focused on the epidemiology and pathogenesis of enterovirus A71, an emerging virus that causes severe neurological disease. She leads a laboratory with research interests in epidemiology and pathogenesis of emerging viruses such as enterovirus A71, chikungunya, and respiratory viruses. With more than 20 years of research experience, she has over 80 publications, and has been involved in many research programs and grants at both national and international levels. Dr. Chan also served as an Associate Editor of BMC Infectious Diseases and guest editor in PLOS Neglected Tropical Diseases. She has multiple joint publications with collaborators from Asia, Europe, and the USA. Her studies have led to a better understanding of how viruses spread and infect humans. 

Dr Fatimah Salim, PhD (Chemistry) is currently a senior lecturer of chemistry at the Centre of Foundation Studies, UiTM. She is also a research fellow at Atta-ur-Rahman Institute for Natural Product Discovery (AuRIns), UiTM. She is a registered chemist and has been appointed as a committee member of Organic and Biomolecular Chemistry Section, Malaysian Institute of Chemistry (IKM). She is an active member of Young Scientist Network- Academy of Science Malaysia (YSN-ASM) and a lifetime member of Malaysian Natural Product Society (MNPS). She is an editor for Suara Saintis Muda of YSN Science Communication Working Group. While her research interest covers a broad spectrum of chemistry, she is trained in structure identification, isolation, elucidation of secondary metabolites from plants and microbes. She is also into quantum mechanics calculation in modelling spectroscopic characteristics of chiral molecules predicted through DFT and TD-DFT methods. 

Dr Khayriyyah Mohd Hanafiah is senior lecturer in Medical Microbiology at Universiti Sains Malaysia, and an affiliate of Young Scientists Network-Academy of Sciences Malaysia. She is active in science communication and infectious disease biomedical research. She was the first female Asian champion of FameLab, the world’s longest running science communication competition, in 2018. 

Dr Thaigarajan Parumasivam is a senior lecturer at School of Pharmaceutical Sciences, Universiti Sains Malaysia. He is an affiliate of Young Scientist Network – Academy of Sciences Malaysia (YSN-ASM) and an executive member of the Malaysian Society of Pharmaceutical Technology (MSPT). He is also a recipient of Global Young Scientist Summit, Singapore 2019 and 2019 ASEAN ASEAN Fellowship. 

Disclaimer: Science Media Centre Malaysia has collected these comments to provide journalists with a range of expert perspectives on the subject. The views expressed here are personal opinions of the experts. They do not in any way reflect the views of the Science Media Centre or any other organization unless specifically stated. 

**All previous posts about COVID-19 here: https://sciencemediacentremalaysia.com/tag/covid-19/

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