Step 1: Segregation of recyclable used PPE
We recommend segregation of used PPE by the users at the doffing site itself as per the respective institutional biomedical waste management guidelines. Based on the cultural and social practices, acceptability of disinfected PPE for reuse may vary in different settings. Considering these things in mind, it is a good idea to sensitize the potential users about benefits of reusability and allow them to decide whether they want to send the used PPE to trash or the recycle bin at the time of doffing. We recommend to have an illustrative guide for PPE segregation at the doffing site, displayed in an easy-to-understand format of posters (Fig. 2) or pictures including in the native/vernacular language. Basic guiding principles to keep or discard the PPE should be provided as listed below:
1) Used PPE that are weakened in strength, torn, soaking-wet or heavily soiled in patients’ body fluids are not suitable for recycling. Such PPE should be identified during doffing and discarded as per the institutional guidelines (Fig. 2a).
2) Used PPE that are intact or have minor stains are suitable for reuse post-disinfection and should be placed in a designated “Used PPE” biohazard bin during doffing (Fig. 2b).
Step 2: Collection and transport of used PPE for Disinfection
1) After the collection of recyclable used PPE in designated bins (from Fig. 2b), a healthcare worker (HCW) donned in complete PPE gear should bag the used PPE, wipe the bag with 0.5% hypochlorite on the outside, double bag it and wipe the outside bag with 0.5% hypochlorite once again (Fig. 3a).
2) These bags will be transported one-by-one to the door, and should be handed over to another HCW, standing outside for further transportation (Fig. 3b).
Note: HCWs must be donned in proper PPE gear (refer to Table 1 for proper PPE) while handling the used PPE bags. It is important that the used PPE bags are handled strictly as per the institutional guidelines.
3) If the designated PPE Disinfection Facility is within the hospital premises or nearby, the HCW may collect the used PPE bags in a designated trolley (that has a lid for closing), and transport them to the PPE Disinfection facility (Fig. 3c).
4) If the designated PPE Disinfection Facility is present at a distance or outside the hospital premises, the used PPE bags should be first collected into cardboard boxes, and sealed properly prior to transport to the PPE Disinfection Facility by a dedicated Biomedical waste vehicle (Fig. 3d).
Note: Ideally, the PPE collection, and disinfection areas should be in close vicinity, in an isolated or less visited site, preferably near to the areas generating maximum used PPE. The physical proximity will significantly minimize the biosafety risk associated with the transportation.
Step 3: Receiving of used PPE bags at the PPE Disinfection Facility
A proposed PPE Disinfection Facility should ideally be constructed at an isolated area, and should be designed to have dedicated rooms for donning, doffing, bag storage area, PPE Disinfection area and Post-disinfection quality check area and Post-disinfection storage of used PPE. The size of the storage and disinfection rooms in the facility should be proportionate to the PPE utilization capacity of the healthcare institution.
1) The Used PPE bags (from Fig. 3c and/or 3d) should be received at the entrance of the PPE Disinfection Facility by a dedicated HCW and carried to the storage area (Fig. 4a).
Features of storage area:
a. Preferably the storage room should have cubicle-type partitions (5 - 8 feet) such that a clear area of at least 3 - 4’ is left from the wall to ensure free movement of man and material (Fig. 4b).
b. The Used PPE storage area should have ample space to hold PPE for at least 3-5 days. Since the SARS-CoV-2, the etiological agent of COVID-19, has a variable survival on various surfaces, storage of used PPE will allow a natural reduction of viral load (Kampf et al., 2020), further minimizing the biohazard for the workers operating the facility.
c. These cubicle areas should be numerically labelled for ease of record keeping and would hold the double bagged used PPE which may include coveralls, face-shields, goggles, N-95 masks etc.
d. Each cubicle should have a clear signage (Fig. 4) of date of receiving and processing due date.
Note: It is crucial for the Facility to maintain a consistent record and cataloguing of each batch of Used PPE bags. The access to the facility should be tightly regulated and if possible, should be monitored using CCTV cameras.
Step 4: Transport of used PPE from storage area to the Disinfection area
From the PPE collection area, the bags would be transported to the disinfection area as per the biosafety compliance work-flow. The below mentioned work-flow is tailored for a VHP-based disinfection facility but most of the precautions listed here are universally applicable intendent of method of disinfection.
Features of PPE Disinfection area:
a. The area designated as such should be closer to the collection area, and should have electrical supply preferably with a UPS/generator back-up to run the VHP machine.
b. The VHP machine requires making dilutions with distil water, so access to distil/autoclaved water, measuring cylinders, and other accessories for hand hygiene of the person operating the machine should be provided.
c. The room should be air-tight to the extent possible to ensure proper exposure time to PPEs Since the disinfection process is dependent on achieving a minimum vapour concentration with sufficient contact time, any leakage may compromise the disinfection process.
d. The room size should be compatible with the capacity of the VHP machine. In our hands, even though capacity of the machine was high, a room size of less than 3500 cu ft. worked the best due to practical difficulty to control vapour leak in larger rooms in our settings.
e. The VHP room should preferably have two independent doors, which can be dedicatedly used to establish a biosafety compliant workflow - One door for transferring the bags containing used PPEs, while another one with access towards the clean area exclusively to allow a smooth collection of the sterilized PPEs after the disinfection cycle.
f. The room door should preferably have a glass pane to allow inside view without the need of opening the door. Having a small glass pane is very useful as one can instruct by gesture or also carry out visual inspection whether all the vapours are cleared once the process is over.
g. The room should have appropriate air-conditioning to keep the ambient temperature inside. And the area should have access control options, either manually or automatically with proper entry and exit records.
h. The disinfection room would have a stepper, gloves, disinfectant solution, and ready to use VHP machine inside. Additional items such as small tables etc. may be kept based on requirements.
Step 4.1: Receiving used PPE bags in Disinfection area
1) The HCW wearing appropriate PPE (Table 1) will transport the used PPE bags to the gate of the VHP disinfection room by using a dedicated wheel cart/trolley (Fig. 5a).
2) The HCW will first carry out the required number of bags inside the room and keep them close to the door (Fig. 5b).
3) Prior to opening the Used PPE bags, the HCW must manually program the VHP machine as per the room dimensions (length × width × height in feet) and adding the required volume of hydrogen peroxide solution (please refer to Table 2, Step 5). This programming is a onetime requirement that should be done prior to the very first disinfection run (in our hands, ~2000 cu feet rooms requires ~ 650ml of 6 – 8% stabilized H2O2).
Note: The vaporizer should be placed on a stable and firm surface such that should not be any obstruction in front of the machine nozzle for at least 3 feet at a 45° angle.
Step 4.2: Arranging used PPE in the disinfection room
4) The bags should be opened individually to take out the inner bag. This inner bag should be carried towards the end of the room as indicated in Fig. 6a.
5) The HCW should carefully take out the used PPE coveralls one-by-one, and straightened without folds, exposing the outer surface, zip open and keeping the front side of the used PPE away from the HCW’s face (Fig. 6b).
Note: The coveralls should be hung on hangers (hangers may be kept in a bucket having freshly prepared 1% hypochlorite solution prior to use) onto the cloth lines such that it is at least 6 inches above floor, 6 inches away from the side walls and 6 inches below ceiling, with 1-foot distance between two coveralls on a line and at least a 2 feet distance between the two rows. This is to ensure efficient diffusion of vapours during the disinfection process.
6) Used N-95 masks should be aligned on grilled wire racks (Fig. 7a) and used face shields to be arranged on table surface (Fig. 7b). If powered air purifying respirators (PAPR) are to be disinfected, they can also be hanged with cloth lines to allow complete exposure.
7) To ensure quality assurance for each disinfection run, we recommend keeping minimum of two Biological Indicator strips (e.g. Bacillus stearothermophilus spores) on the used PPE at the corners of the room farthest from the machine, for quality assurance (Fig. 7c).
Step 5: Running of the disinfection cycle: VHP machine
1) The user must adhere to the manufacturer’s instructions to operate the VHP machine.
2) Briefly, once the machine is properly set-up, press the start button and, exit the room through the door towards dirty area and seal the door from the outside. Almost all VHP machines have a provision for a lag period (30 sec to 1 min) to allow the HCW to exit the room prior to peroxide vapour generation.
3) Upon exit, the HCW must seal the room door from the outside.
4) The room size, run time, capacity to disinfect PPE and amount of peroxide required in our hands are listed below (Table 2):
Note: Hydrogen peroxide used in the disinfection process should be stabilized with a chemical agent. We have used a stock solution of 11 - 12% H2O2 stabilized with 0.01% silver nitrate in our experiments.
5) Post-run, we recommend a minimum of 1 to 1.5 hr contact time to ensure disinfection and vapour clearance. If the room is opened at an early time following disinfection, the residual vapors of H2O2 may cause irritation and discomfort in eyes.
6) The machine should be cleaned at the end of the day as per the manufacturer’s instruction. Usually, a 10 min cycle with distilled water may be used, for machine nozzle cleaning and avoid any clogging.
Step 6: Post-disinfection procedures
Step 6.1: Collection of exposed biological indicators and disinfected PPE
1) The worker must wear an appropriate PPE gear (Table 1) and enter the room via the “clean area” (Fig. 8a).
2) After entry, the HCW must FIRST collect the exposed biological indicators in respective media tubes (Fig. 8b) for testing for quality assurance.
Note: The biological indicator spore strips will be collected in a tube pre-filled with 5-6 ml of brain heart infusion broth or tryptic soy broth. The tubes are properly sealed, packed in a polythene bag, wiped clean with 0.5% hypochlorite and pass over one-by-one to a HCW standing in the “clean area” outside the room (Fig. 9a). These tubes will be transported by the HCW to a dedicated culture room with an incubator to test for quality assurance.
3) After transferring the control strips outside the room, the disinfected PPE will be collected, packed in bags, and bags will be labeled with disinfection cycle number and date (on the front). The bags should be wiped with 0.5% sodium hypochlorite prior to handing over to the second HCW standing in the clean area.
4) These disinfected bags should be kept in a dedicated area and MUST NOT be opened until the test results of indicators confirms a successful disinfection (Step 6.2). If for some reason the disinfection process does not work, the bags of the corresponding run should be taken back to the disinfection room and would be processed like other used PPE (Step 4).
5) After handing over the disinfected PPE, the worker may continue to work or prepare for next cycle, or else may move to doffing area, change and exit the facility.
Step 6.2: Quality assurance of a disinfection cycle
6) After transport of the indicator tubes to the culture facility, these will be incubated at 55ºC for 3-5 days under shaking conditions (180 rpm) as per the manufacturer’s instructions. This is required to determine the growth or recovery of biological indicators that were exposed in a given disinfection cycle.
7) Change in turbidity is considered as a measure of growth; and an absence of growth indicates a successful sterilization cycle (Fig. 10). If doing CFU, a difference of a minimum of 3 log (i.e. more than 99.9% between positive control and disinfected biological indicator) may be considered a successful run.
Step 7: Post-disinfection quality check of PPE for reuse
Once the successful disinfection is established (no growth in spores kept in media till 72 hours, Fig. 10), the bags will be transferred to the post-disinfection processing area.
1) The bags will be opened here and the disinfected PPE bags may be looked for small spots/stains etc., and can be cleaned with 70% ethanol or 0.1% hypochlorite or any other cleaning agent as quality check (Fig. 11).
2) If any torn PPE or N-95 masks are observed, it should be discarded at this step.
3) Once the post-disinfection Quality check is complete, the decontaminated PPE may be packed and can be distributed as per the requirement.
a. The disinfection protocol is valid for N-95 masks, glasses and goggles, and hence can be used to develop a single reprocessing site for all the used PPE.
b. Disinfected PPE including coverall and masks should be checked for physical integrity.
c. The number of disinfection cycles undergone by a particular PPE item is also dependent on the quality of PPE item used and efforts must be made to ensure that no deformity exist in the PPE.
d. Appropriate biological indicator should be used in the room for each cycle for quality control. If room is big (>2000 cu ft., two biological indicators may be used, one each at the both ends of the room.
e. A proper cataloguing of disinfected PPE may be considered during recirculation to ensure tracking of the number of disinfection cycles undergone by the PPE item.