Disinfection of Environmental Surfaces and Articles Used for COVID 19 Patient

: Disinfection of environment surfaces and articles used for COVID 19 patient plays an important role in reducing indirect transmission of SARS-CoV-2 – the virus responsible for COVID-19. Depending on the type of surface, SARS-CoV-2 can remain viable between eight hours to several days. The surfaces are contaminated when virus-containing droplets land on surfaces, or when someone with contaminated hands touches these surfaces. Virus contamination in both health care as well as non-health care settings can be reduced by good disinfection practices. Cleaning and disinfection is fundamental because it kills any remaining germs on the surface and thereby reduces the spread of germs. Therefore disinfection of the health care environment is vital in reducing infection rate. Following strict cleaning and disinfection protocols is the key to make sure that the patient as well as the health care worker remains safe. It is also important to increase awareness on how to clean and disinfect the articles used for Covid patient, so that the disease not spread to other patients and at the same time health care workers are protected. The disinfectant and its concentration should be carefully selected to avoid or minimize toxic effects on household members and also avoid damaging surfaces.


Introduction
COVID-19 is an acute respiratory disease caused by a novel Coronavirus (SARS-CoV-2) It is transmitted through contaminated surfaces/objects as well as through respiratory droplets. [1] Environmental high touch surfaces in health-care settings: furniture items such as tables, chairs, walls, light switches and computer peripherals, electronic equipment as well as the surfaces of medical equipment such as blood pressure cuffs, stethoscopes, wheelchairs and incubators carry risk of transmission of virus. Though the virus survives on environmental surfaces for varied period of time as shown in table 1, but it gets easily inactivated by chemical disinfectants. [2]  Coming into contact with contaminated surfaces and subsequently transferring the virus to mucous membranes may transmit the virus and infection. Therefore it is important to limit the spread and transmission of the virus by: i. Regular cleaning and disinfection of high touch surfaces like switches, countertops, handles, telephone, door knobs, tables etc ii. Practicing hand hygiene iii. Avoiding touching the face iv. Using appropriate personal protective equipment (PPE). The main objective of this review article is to provide updated information about disinfection of environmental surfaces and articles in context of the ongoing COVID 19 pandemic. It will also guide health-care professionals and health authorities in developing policies and standard operating procedures (SOP) on the cleaning and disinfection of environmental surfaces used for COVID-19 patient.

Principles of Environmental Cleaning and Disinfection
Cleaning is a first step in any disinfection process because it helps to remove pathogens on contaminated surfaces. Cleaning with water and soap/chemicals helps in physical removal of pathogens or any organic material (blood, secretions and excretions) from the surfaces. Therefore, a chemical disinfectant, such as chlorine or alcohol, (prepared and used according to the manufacturer's recommendations for volume and contact time) should be applied after cleaning to kill any remaining microorganisms. SARS-CoV-2 is sensitive to ultraviolet radiation, Heat (56°C for 30 minutes) and disinfectants as mentioned below. [3,4]

Common Chemical Disinfectants
Sodium hypochlorite solution, alcohol based disinfactants, Glutaraldehyde solution and Hydrogen peroxide 0.5% are the common chemical disinfectants which break the chain of transmission of infection of SARS-COV-2

Sodium Hypochlorite Solution
Sodium hypochlorite is used for a variety of cleaning and disinfecting purposes as a common bleaching agent. Table 2 shows Guidelines for Preparation of sodium hypochlorite solution as recommended by WHO. [5]  According to CDC guidelines, hypochloride solution should be prepared fresh in a ventilated area with a contact time at least 10 minutes and avoiding direct contact with the skin and eyes. The fresh prepared solution should be prepared and stored in plastic containers as it is corrosive to metal surfaces.
The other important points to be kept in mind while using hypochlorite solution is to always check the concentration of sodium hypochlorite in bleach and prepare as recommended. Cleaning staff should be attired in suitable PPE. Do not use disinfectants spray on potentially highly contaminated areas as it may create splashes. Avoid mixing the bleach solution with acidic solution as it may release ammonia which can be very toxic. [6]

Alcohol Based Disinfectant
The European Centre for Disease Prevention and Control (ECDC) recommends alcohol based disinfectants with an concentration 60-80% (Ethyl alcohol or isopropyl alcohol) which is a potent virucidal agent inactivating all of the lipophilic viruses. 70% isopropyl alcohol works as intermediate level germicidal agent to disinfect non critical items in hospital settings like BP cuff, thermometer, skin asepsis before any aseptic procedure. Isopropyl alchohol volatility changes with the storage time specially when exposed to light. Since alcohol is flammable, it should be used in well-ventilated spaces only. When alcohol are used repeatedly for Prolonged period of time, it can cause discoloration, swelling, hardening and cracking of rubber and certain plastics. [7]

Glutaraldehyde Solution
Glutaraldehyde solution (2.45%) is a high-level disinfectant which is most commonly used for disinfection of medical equipment such as endoscopes, spirometry tubing, dialyzers, transducers, anesthesia and respiratory therapy equipment, hemodialysis dialysates, and reuse of laparoscopic disposable plastic trocars. The contact time of at least 20 minutes (at or above 20°C) is effective for this highlevel disinfectant solution. It has shelf life of 14 days when gets activated (by use of alkalinating agents to make pH 7.5-8.5). The benefits of using Glutaraldehyde is that it is noncorrosive to metal and also does not damage lensed instruments, plastics or rubber. [8]

Hydrogen Peroxide
Kampf G, Todt D, Pfaender S, Steinmann E; 2020 have shown effective disinfection activity of Hydrogen peroxide at a concentration of 0.5%within less than 3 minutes against Corona-virus. Hydrogen peroxide 0.5% is shown with microbicidal activity against this virus within 1-minute exposure time. Hydrogen peroxide is a stable and effective disinfectant for inanimate surfaces like disinfecting soft contact lenses, tonometer biprisms, ventilators, fabrics and endoscopes. [9]

Surface Disinfection
i. Cleaning and disinfection should follow a consistent and correct routine in line with standard hospital grade disinfection procedure. The cleaning routine should involve an initial wash with a water and detergent solution followed by disinfection agents. ii. Cleaning should start from the cleanest to the dirtiest areas and higher surface to lower surfaces. Disinfectant solutions must be prepared and used according to the manufacturer's recommendations for volume and contact time. [10] iii

Articles Disinfection. [13, 14]
Patient care items that can contribute to the spread of infection include Stethoscopes, Blood pressure cuffs, Monitors, X ray machine, USG machine, Stretchers, backboards, and immobilization devices, Laryngoscope blades, beds/ railings, ventilators, cardiac monitors etc. Table  no 3 shows the cleaning and disinfection of articles used in care of COVID 19 patient.

Discussion
There are various articles which supports the importance of proper disinfection as the effective means to reduce the spread of the disease.
Adrija Roy, Swayam Pragyan Parida, Vikas Bhatia suggested that surface disinfection and handwashing with soap and water is the fastest, easiest, and most effective way to halt or reduce the spread of SARS-CoV-2 the virus resulting in the coronavirus disease (COVID-19). [15] The importance of Disinfection was suggested by Kampf G, Todt D, Pfaender S, Steinmann E. to be an effective method to reduce the viral load on surfaces. [9] The Australian Government Department of Health claimed that virucidal agent such as hypochloride solution is sufficient to inactivate the virus. [16] Hulkower and colleagues recommend that 1:100 solution of sodium hypochlorite, mixed in accordance with manufacturer recommendations, as effectively inactivating coronaviruses. [17]

Conclusion
Disinfecting of the environmental surfaces and the article used for covid19 patient will not only reduce the spread of disease but also will bring a significant change in reduction in the infection rate among health care workers.
It is paramount to ensure availability of recommended disinfectant and cleaning materials in health care settings. Cleaning staff should also be trained as per the WHO recommended procedures and hospital protocols on decontamination practices.