Buffer Stock Protocol
v1.14
05/09/2020 (first version 03/15/20)
gblonder@bu.edu
877 271-8282

Note added 05/09/202: Mass General Brighton and www.n95decon.org held an open webinar to review their most current findings on UV-C, peroxide vapor and dry/wet heat decontamination. Extermely useful information- I recommend watching the video and returning to the www.n95decon.org site for slides and updated information. In answer to my question whether a one week buffer combined with 125F (50C) heat made sense, they thought it was plausible and deserved more study.

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Concept: At room temperature Covid-19 exhibits a half-life of hours to a day, depending on the surface. Rather than using chemicals or unproven treatments that might destroy or reduce the ability of PPE to block viral transmission, or are too expensive for use in developing nations¹, BSP simply allows time for the virus to naturally decay. A days worth of PPE is securely labeled, segregated and stored for a week. It is then re-used as if new. Over this week-long time period, the virus *should* die off to de minimus levels that are considered acceptable in an emergency setting . Gentle heat, 125F (~50c) should accelerate viral decay², without negatively effecting the PPE's performance.

Proposed protocol:

1. Daily PPE are collected, inspected and damaged units destroyed.
2. Recyclable units are stamped with the date for tracking (and perhaps index to return to previous user).
3. These dated units are hung/placed in a secure room.
1. Preferably ventilated at negative pressure.
2. The following day’s PPE are segregated on CLEARLY marked shelves by date, or in a separate room or temporary facility, such as as shipping container or medical tent.
3. After a week, there will be 7 unique storage areas.
4. Samples of incoming PPE are swabbed to determine initial viral load
1. While tracking individual items through the BSP is preferable, an average viral load measurement reduces the burden on test kits, i.e. you  can test multiple PPE with one swab.
2. Each day, viral test samples are taken from PPE in each daily storage area to confirm loads are reducing in a predictable manner to acceptable levels of sanitization. Other microbes may be monitored in the same manner.
5. After a week, the now safe(r) PPE are removed from BSP and worn.
6. The cycle repeats.

Evidence and other support Material:

• Prof. Peter Tsai, one of the inventors of N95 electrostatic filter material made a similar suggestion.
• www.n95decon.org is acting as a clearing house for various N95 decontamination processes.
• The half life of Covid-19 depends on the surface, but is under 12 hours, implying clearance by the end of a week.
• This Chinese study from early Feb 2020 indicates 160F heat will deactivate Covid-19 in 30 minutes, leaving the N95 mask fully functional
• An NIH preprint 4/11/20 mentions 70C (160F) as effective, tested up to three reuses. Also discussed UV, vaporized peroxide and moist heat.
• CDC filtered faceplate protocols and tests. Moist heat, UV and peroxide vapor.
• FDA medical device guidance has a number of useful resources, constantly updated

Note 1: While peroxide vapor has been shown to effective on N95 masks, its use on PPE is problematic. In some situations, other pathogens (MERs, e-coli, etc) may also contaminate the PPE. Coats, hoods and face-shields are complex shapes, preventing the peroxide vapor from penetrating into all nooks and crannies, including the thick elasics. Which leaves portions of the PPE untreated. Some techniques will minimize this "shadowing" effect (for example, electrostatic spraying or perhaps repeated cycles of vacuum/peroxide vapor introduction. And corona discharge with careful grounding might refresh the N95 filter), again this is a slow and complex process. Large scale heating, whether in an insulated shipping container with electric heaters, or simply repurposed greenhouses, should be sufficient to reach 125F. To date, I am unaware of any direct laboratory evaluations of the BSP protocol.

Note 2: Hospitals should work with PPE suppliers to change their designs so they can be BSP gentle heat sanitized 10 times. This will require modifications in materials choices (new adhesives and plastics, for example). The PPE should incorporate areas to mark for tracking, and perhaps a heat sensitive color bar indicating how many times the PPE has been BSP treated.