SARS-CoV-2 quantification in N95 respirators after thermal disinfection*
| N95 model (3M) | Pretreatment | Titre, Log TCID50/mL (mean ± SD) | ||
|---|---|---|---|---|
| Control (no heat treatment) | 70°C/0% RH, 60 min | 70°C/0% RH, 60 min with 5-min cool-down mid cycle | ||
| 1860S | Unprocessed | 5.62 ± 0.21 | U | U |
| 10× heat treated | 5.69 ± 0.11 | U | U | |
| 8110S | Unprocessed | 5.70 ± 0.004 | U | U |
| 10× heat treated | 5.77 ± 0.24 | U | U | |
| 8210S | Unprocessed | 5.21 ± 0.50 | U | U |
| 10× heat treated | 5.66 ± 0.08 | U | U | |
| 9105S | Unprocessed | 5.56 ± 0.27 | U | U |
| 10× heat treated | 5.45 ± 0.29 | U | U | |
Note: RH = relative humidity, SARS-Cov-2 = severe acute respiratory syndrome coronavirus 2, SD = standard deviation, TCID50/mL = 50% tissue culture infective dose per mL, U = undetectable, detection limit = 100 TCID50/mL.
↵* Shown are quantifications of the infective doses of SARS-CoV-2 after a single cycle of thermal disinfection (70°C/0% RH) of new N95 respirators, and respirators that were pretreated with 10 disinfections. For each condition, we used 3 samples per respirator model (e.g., 12 pieces of unprocessed 1860s masks were virus inoculated and of those, 3 underwent no heat treatment, 3 underwent 60 min at 70°C at 0% RH and 3 underwent 60 minutes at 70°C at 0% RH with 5-min cool-down mid cycle). Infectious SARS-CoV-2 could not be recovered from the disinfected masks, showing effective decontamination. Increasing the RH during thermal disinfection is therefore not required to inactivate SARS-CoV-2 in N95 respirators.