FAQ - What you need to know about surface disinfection
Coronavirus are a large family of viruses that are known to cause illness ranging from the common cold to more severe diseases, such as the Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS).
The current understanding of the transmission mechanism for COVID-19 is mainly by close-contact via large droplets (aerosol transmission remains to be verified). Understandably, hand hygiene is the most direct means of preventing an infection, but hands are not the only source of infection. Viruses can survive on environmental surfaces for an extended period of time and transmission via an individual touching a contaminated surface has been shown to be plausible based on our understanding of other highly transmissible respiratory diseases, such as influenza (1). This route of transmission (via contaminated surfaces) has now been formally recognized by WHO as one of the routes for COVID-19 transmission (2).
How long can SARS-CoV-2 stay viable on surfaces?
Coronaviruses can generally be detected on surfaces for 2 hours to as long as 9 days (3). A more specific study on SARS-CoV-2 (the virus which causes COVID-19) showed that the virus is able to survive and remain infectious longer on hard surfaces such as stainless steel (72 hours) and plastic (48 hours) and 24 hours on more absorbent material such as cardboard (4).
Does environmental cleaning/disinfection eliminate SARS-CoV-2 and help prevent COVID-19 transmission?
Yes. The immediate environment around the patients (e.g. ICU) is heavily contaminated with SARS-CoV-2 virus (5) and routine environmental cleaning has been shown to effectively remove SARS-CoV-2 virus compared with no cleaning in contaminated wards (6). Hence, cleaning and disinfecting surfaces is regarded as part of the multi-model strategy (including good hand hygiene) to break the transmission of COVID-19.
Which surfaces need to be disinfected?
In hospitals, high touch surfaces, such as door knobs, door handles, bed rails, cardiac table, floors and patients' immediate surroundings including the floors have to be thoroughly disinfected (7).
In non-hospital areas, high touch surfaces such as door knobs, light switches, common use devices such as hot desk computers and telephones.
How to disinfect surfaces properly to prevent COVID-19?
According to CDC guidelines (8), cleaning of hard non-porous surfaces using soap or detergent with water should be carried out prior to disinfection. Chemical disinfectants containing active ingredients like alcohol and quaternary ammonium compounds are effective against SARS-CoV-2. Kindly refer to the following for the steps needed for commonly used surface disinfection products e.g. ready-to-use impregnated wipes:
- Wear recommended PPE; gloves when handling wipes.
- Remove any visible dirt or debris before disinfection. Use the wipe to disinfect the surface from clean to dirty areas in a "S" pattern without overlapping the same area.
- Ensure that surface area is fully covered and kept wet for the required contact time as according to manufacturer's instructions (against enveloped viruses) to achieve optimal surface disinfection.
- Change the wipe if it becomes too dirty or dry. Use another wipe when necessary or when surface contamination is high.
- Discard all used wipes appropriately and according to the individual institution's waste disposal protocol.
Do all surface wipes eliminate SARS-CoV-2 effectively?
No. As simple as it sounds, 'wiping down the surface to mechanically remove and eliminate the pathogens of concerns' is more than what we think. There are a couple of key considerations, such as the type of disinfectants, virucidal tests and wipe materials when it comes to picking or deciding which is the right wipes for surface disinfection in this pandemic.
Does the type of disinfectants matter for effective disinfection?
Yes. The antimicrobial or antiviral property of the wipes is heavily dependent on the type of disinfectant/chemicals that are able to 'kill' the pathogens of concern. For SARS-CoV-2, alcohol remains the recommended disinfectant of choice (by WHO), but that doesn't means that other chemicals (e.g. QACs-based) are not effective. Effectiveness of which depends on the virucidal test which the disinfectants are being tested on.
For e.g. for SARS-CoV-2, the verification whether the disinfectant renders efficacy against the virus depends on the 'test' carried out by the manufacturer. One of the recognized tests according to the European Norm (EN) standard named EN14476 (a microbiological test against virus) - a positive result of the test means that the solution within the wipes/tissue is efficacious against enveloped viruses, such as coronaviruses.
Does the quality of the wipes matter?
Yes. The material in the wipes is the key towards effective disinfection. The wipe has to be of the right material composition being able to hold the right amount of liquid, transferring the right amount of liquid onto the surface to achieve antimicrobial effect and most importantly, being able to pick up the pathogens without spreading it across the area being wiped - for that EN16615 test (looking at the wipes as a whole; wipes + disinfectant) is the highest level of test for antimicrobial wipes under the recognition of the European Standard committee.
For wipes, one should never assume they all have EN16615 certification. More than often, most wipes have EN14476 certification without EN16615 - therefore this also raises the question if those wipes are really doing what they are supposed to do?
Can I get infected by touching delivery goods from countries with infection cases?
Possible but risk is low. Given that SARS-CoV-2 can survive on surfaces for an extended period of time, the risk of picking up a virus from a parcel is possible. However, we do not yet fully understand how much viruses can be transferred from a contaminated surface to our hands and from our hands to our face. Other unknowns also include how much virus particles are actually required to initiate an infection in humans. Nonetheless, the best approach to prevent getting infected is to clean the box (if feasible) or the best prevention precaution is to wash/sanitize the hands after handling suspicious delivery goods.
Can COVID-19 be transmitted through coins, dollar notes and even credit cards?
There is no evidence to prove that SARS-CoV-2 can remain viable on coins, dollar notes and credit cards. These items pass through different hands and may come into contact with many other microbes including bacteria. It is strongly recommended to maintain good hand hygiene through soap and water or alcohol based hand rubs and avoid touching our faces after handling coins, dollar notes and credit cards.
*article from Schulke & Mayr