Utility of SARS-CoV-2 Genomic Sequencing for Understanding Transmission and School Outbreaks.

OBJECTIVE: An understanding of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) transmission in schools is important. It is often difficult, using epidemiological information alone, to determine whether cases associated with schools represent multiple introductions from the community or transmission within the school. We describe the use of whole genome sequencing (WGS) in multiple schools to investigate outbreaks of SARS-CoV-2 in the pre-Omicron period. STUDY DESIGN: School outbreaks were identified for sequencing by local public health units based on multiple cases without known epidemiological links. Cases of SARS-CoV-2 from students and staff from 4 school outbreaks in Ontario underwent WGS and phylogenetic analysis. The epidemiological clinical cohort data and genomic cluster data are described to help further characterize these outbreaks. RESULTS: A total of 132 positive SARS-CoV-2 cases among students and staff from 4 school outbreaks were identified with 65 (49%) of cases able to be sequenced with high-quality genomic data. The 4 school outbreaks consisted of 53, 37, 21 and 21 positive cases; within each outbreak there were between 8 and 28 different clinical cohorts identified. Among the sequenced cases, between 3 and 7 genetic clusters, defined as different strains, were identified in each outbreak. We found genetically different viruses within several clinical cohorts. CONCLUSIONS: WGS, together with public health investigation, is a useful tool to investigate SARS-CoV-2 transmission within schools. Its early use has the potential to better understand when transmission may have occurred, can aid in evaluating how well mitigation interventions are working and has the potential to reduce unnecessary school closures when multiple genetic clusters are identified.

Effect of Wearing a Face Mask on Hand-to-Face Contact by Children in a Simulated School Environment: The Back-to-School COVID-19 Simulation Randomized Clinical Trial.

Importance: Wearing a face mask in school can reduce SARS-CoV-2 transmission but it may also lead to increased hand-to-face contact, which in turn could increase infection risk through self-inoculation. Objective: To evaluate the effect of wearing a face mask on hand-to-face contact by children while at school. Design, Setting, and Participants: This prospective randomized clinical trial randomized students from junior kindergarten to grade 12 at 2 schools in Toronto, Ontario, Canada, during August 2020 in a 1:1 ratio to either a mask or control class during a 2-day school simulation. Classes were video recorded from 4 angles to accurately capture outcomes. Interventions: Participants in the mask arm were instructed to bring their own mask and wear it at all times. Students assigned to control classes were not required to mask at any time (grade 4 and lower) or in the classroom where physical distancing could be maintained (grade 5 and up). Main Outcomes and Measures: The primary outcome was the number of hand-to-face contacts per student per hour on day 2 of the simulation. Secondary outcomes included hand-to-mucosa contacts and hand-to-nonmucosa contacts. A mixed Poisson regression model was used to derive rate ratios (RRs), adjusted for age and sex with a random intercept for class with bootstrapped 95% CIs. Results: A total of 174 students underwent randomization and 171 students (mask group, 50.6% male; control group, 52.4% male) attended school on day 2. The rate of hand-to-face contacts did not differ significantly between the mask and the control groups (88.2 vs 88.7 events per student per hour; RR, 1.00; 95% CI, 0.78-1.28; P = >.99). When compared with the control group, the rate of hand-to-mucosa contacts was significantly lower in the mask group (RR, 0.12; 95% CI, 0.07-0.21), while the rate of hand-to-nonmucosa contacts was higher (RR, 1.40; 95% CI, 1.08-1.82). Conclusions and Relevance: In this clinical trial of simulated school attendance, hand-to-face contacts did not differ among students required to wear face masks vs students not required to wear face masks; however, hand-to-mucosa contracts were lower in the face mask group. This suggests that mask wearing is unlikely to increase infection risk through self-inoculation. Trial Registration: ClinicalTrials.gov Identifier: NCT04531254.

Trends in Clostridioides difficile infection rates in Canadian hospitals during the coronavirus disease 2019 (COVID-19) pandemic.

The coronavirus disease 2019 (COVID-19) pandemic has placed significant burden on healthcare systems. We compared Clostridioides difficile infection (CDI) epidemiology before and during the pandemic across 71 hospitals participating in the Canadian Nosocomial Infection Surveillance Program. Using an interrupted time series analysis, we showed that CDI rates significantly increased during the COVID-19 pandemic.

Impact of COVID-19 Public Health Protocols on Teachers Instructing Children and Adolescents During an In-Person Simulation.

Objective: As a result of the COVID-19 pandemic, public health agencies and school boards across Canada enacted new protocols, including face masks, physical distancing and enhanced hygiene, to support the safe reopening of in-person school. This study explored the experiences and perceptions of teachers instructing children and adolescents in person during a two-day school simulation. Method: This study was part of a large school simulation exercise conducted in Toronto, Ontario. Kindergarten to grade 12 teachers taught in classrooms with either masked students, or students who were un-masked or only masked when physical distancing was not possible. A qualitative descriptive phenomenology approach was utilized, and data were collected via virtual focus groups. Qualitative data analysis involved multiple rounds of inductive coding to generate themes. Results: The sample included 14 teachers (92.9% female; 85.7% White), with a median of 9.5 years teaching experience. Three primary themes emerged: 1) learning to navigate public health measures, 2) needing to adapt teaching strategies and 3) striving to manage conflicting priorities. The majority of teachers reported that mask-wearing and physical distancing impacted their classroom teaching, communication and connection with students. Conclusions: As schools transition to in-person instruction, teachers will be required to play dual roles in education and public health, with implications on safety, teaching and professional identity. Public health agencies and school boards are encouraged to engage teachers in ongoing conversations regarding in-person school planning and operations. Furthermore, evidence-based interventions, including increased teaching development programs, are recommended to support teachers during the COVID-19 pandemic.

Objectif: Conséquemment à la pandémie de la COVID-19, les organismes de santé publique et les conseils scolaires de tout le Canada ont mis en œuvre de nouveaux protocoles, notamment des masques, une distanciation physique et une hygiène accrue, afin de soutenir la réouverture prudente de l'école en personne. La présente étude a exploré les expériences et les perceptions des professeurs instruisant les enfants et les adolescents en personne durant une simulation scolaire de deux jours. Méthode: La présente étude faisait partie d'un grand exercice de simulation scolaire mené à Toronto, Ontario. Les professeurs de la maternelle à la 12e année enseignaient dans des classes où les élèves étaient soit masqués, soit non masqués, soit seulement masqués quand la distanciation physique n'était pas possible. Une approche de phénoménologie qualitative descriptive a été utilisée, et les données ont été recueillies par des groupes de discussion virtuels. L'analyse des données qualitatives impliquait de multiples rondes de codage inductif pour générer des thèmes. Résultats: L'échantillon comportait 14 professeurs (92,9 % de sexe féminin; 85,7 % Blancs), avec une moyenne de 9,5 années d'expérience d'enseignement. Trois principaux thèmes ont émergé : 1) apprendre à naviguer les mesures de santé publique, 2) la nécessité d'adapter les stratégies d'enseignement et 3) s'efforcer de gérer les priorités conflictuelles. La majorité des professeurs a déclaré que le port du masque et la distanciation physique influaient sur leur enseignement en classe, sur la communication et la connexion avec les élèves. Conclusions: Tandis que les écoles font la transition à l'enseignement en personne, les professeurs devront assumer des doubles rôles en éducation et en santé publique, impliquant la sécurité, l'enseignement et l'identité professionnelle. Les organismes de santé publique et les conseils scolaires sont invités à faire participer les professeurs à des conversations actuelles relativement à la planification et aux activités de l'école en personne. En outre, les interventions fondées sur des données probantes, notamment les programmes accrus de développement de l'enseignement, sont recommandées pour soutenir les professeurs durant la pandémie de la COVID-19.

Return to school and mask-wearing in class during the COVID-19 pandemic: Student perspectives from a school simulation study.

Objectives: This study examined children's perspectives about returning to in-person school following lockdown due to the pandemic and about mask-wearing in class, as well as the mental health of children and parents during the pandemic. Methods: This cross-sectional study was part of a 2-day school simulation exercise that randomized students to different masking recommendations. Parent-report of mental health and post-simulation child-report of COVID-19-related anxiety and mask-wearing were analyzed using descriptive and multiple regression analyses. Semi-structured focus groups were conducted with older students to supplement questionnaire data. Results: Of 190 students in this study, 31% were in grade 4 or lower 95% looked forward to returning to in-person school. Greater child anxiety about COVID-19 was predicted by increased parent/caregiver anxiety (ß=0.67; P<0.001), and lower parental educational attainment (ß=1.86; P<0.002). Older students were more likely than younger students to report that mask-wearing interfered with their abilities to interact with peers (χ2(1)=31.16; P<0.001) and understand the teacher (χ2(1)=13.97; P<0.001). Students in the group that did not require masks were more likely than students in the masking group to report worries about contracting COVID-19 at school (χ2(1)=10.07; P<0.05), and anticipated difficulty wearing a mask (χ2(1)=18.95; P<0.001). Conclusions: For children anxious about COVID-19, parental anxiety and education about COVID-19 may be targets for intervention. Future research should examine the impact of prolonged implementation of public health mitigation strategies in school on academic achievement and children's mental health.

Underestimation of travel-associated risks by adult and paediatric travellers compared to expert assessment: A cross-sectional study at a hospital-based family pre-travel clinic.

BACKGROUND: Travellers' perception of their risk for acquiring travel-related conditions is an important contributor to decisions and behaviors during travel. In this study, we aimed to assess the differences between traveller-perceived and expert-assessed risk of travel-related conditions in children and adults travelling internationally and describe factors that influence travellers' perception of risk. METHODS: Children and adults were recruited at the Hospital for Sick Children's Family Travel Clinic between October 2014 and July 2015. A questionnaire was administered to participants to assess their perceived risk of acquiring 32 travel-related conditions using a 7-point Likert scale. Conditions were categorized as vector-borne diseases, vaccine-preventable diseases, food and water borne diseases, sexually transmitted infections and other conditions. Two certified travel medicine experts reviewed each patient's chart and assigned a risk score based on the same 7-point Likert scale. Traveller and expert risk scores were compared using paired t-tests. RESULTS: In total, 207 participants were enrolled to participate in this study, 97 children (self-reported, n = 8; parent-reported, n = 89), and 110 adults. Travel-related risk for adults and parents answering for their children were significantly underestimated when compared to expert-assessed risk for 26 of the 32 assessed conditions. The underestimated conditions were the same for both adults and parents answering for children. Travel-related risk was not over-estimated for any condition. CONCLUSIONS: Adults underestimated their children's and their own risk for most travel-related conditions. Strategies to improve the accuracy of risk perception of travel-related conditions by travellers are needed to optimize healthy travel for children and their families.

Désinfection à la chaleur humide des respirateurs N95, inactivation du SRAS-CoV-2 et effets sur les propriétés des respirateurs.

CONTEXTE: La demande sans précédent de respirateurs N95 durant la pandémie de maladie à coronavirus 2019 (COVID-19) a entraîné une pénurie mondiale. Nous avons validé un protocole de décontamination rapide et économique répondant aux normes réglementaires afin de permettre la réutilisation sûre de ce type de masque. MÉTHODES: Nous avons contaminé 4 modèles courants de respirateurs N95 avec le coronavirus du syndrome respiratoire aigu sévère 2 (SRAS-CoV-2) et avons évalué l'inactivation virale après une désinfection de 60 minutes à 70 °C et à une humidité relative de 0 %. De même, nous avons étudié l'efficacité de la désinfection thermique, à une humidité relative allant de 0 % à 70 %, de masques contaminés à Escherichia coli. Enfin, nous avons examiné des masques soumis à de multiples cycles de désinfection thermique: nous avons évalué leur intégrité structurelle à l'aide d'un microscope à balayage, et leurs propriétés protectrices au moyen des normes du National Institute for Occupational Safety and Health des États-Unis relatives à la filtration particulaire, à la résistance respiratoire et à l'ajustement. RÉSULTATS: Une seule désinfection thermique a suffi pour que le SRAS-CoV-2 ne soit plus décelable sur les masques étudiés. En ce qui concerne les masques contaminés à E. coli, une culture de 24 heures a révélé que la bactérie n'était pratiquement plus décelable sur les masques désinfectés à 70 °C et à une humidité relative de 50 %, contrairement aux masques non désinfectés (densité optique à une longueur d'onde de 600 nm : 0,02 ± 0,02 contre 2,77 ± 0,09; p < 0,001), mais qu'elle persistait sur les masques traités à une humidité relative moindre. Les masques ayant subi 10 cycles de désinfection avaient toujours des fibres de diamètre semblable à celui des fibres des masques non traités, et ils répondaient encore aux normes d'ajustement, de filtration et de résistance respiratoire. INTERPRÉTATION: La désinfection thermique a réussi à décontaminer les respirateurs N95 sans compromettre leur intégrité structurelle ni modifier leurs propriétés. Elle pourrait se faire dans les hôpitaux et les établissements de soins de longue durée avec de l'équipement facilement accessible, ce qui réduirait la pénurie de N95.

Risk of COVID-19 Infections and of Severe Complications Among Survivors of Childhood, Adolescent, and Young Adult Cancer: A Population-Based Study in Ontario, Canada.

PURPOSE: Survivors of childhood, adolescent, and young adult cancer are at risk of late effects, including pulmonary and infectious complications. Whether survivors are at increased risk of COVID-19 infection and severe complications is unknown. METHODS: Population-based registries in Ontario, Canada, identified all 5-year survivors of childhood cancer diagnosed age 0-17 years between 1985 and 2014, and of six common adolescent and young adult cancers diagnosed age 15-21 years between 1992 and 2012. Each survivor alive on January 1, 2020, was randomly matched by birth year, sex, and residence to 10 cancer-free population controls. Individuals were linked to population-based laboratory and health care databases to identify COVID-19 tests, vaccinations, infections, and severe outcomes (emergency department [ED] visits, hospitalizations, intensive care unit admissions, and death within 60 days). Demographic, disease, and treatment-related variables were examined as possible predictors of outcomes. RESULTS: Twelve thousand four hundred ten survivors were matched to 124,100 controls. Survivors were not at increased risk of receiving a positive COVID-19 test (386 [3.1%] v 3,946 [3.2%]; P = .68) and were more likely to be fully vaccinated (hazard ratio, 1.23; 95 CI, 1.20 to 1.37). No increase in risk among survivors was seen in emergency department visits (adjusted odds ratio, 1.2; 95 CI, 0.9 to 1.6; P = .19) or hospitalization (adjusted odds ratio, 1.8; 95 CI, 1.0 to 3.5; P = .07). No survivor experienced intensive care unit admission or died after COVID-19 infection. Pulmonary radiation or chemotherapies associated with pulmonary toxicity were not associated with increased risk. CONCLUSION: Cancer survivors were not at increased risk of COVID-19 infections or severe sequelae. These results can inform risk-counseling of survivors and their caregivers. Further study is warranted to determine risk in older survivors, specific subsets of survivors, and that associated with novel COVID-19 variants.

Impact of the COVID-19 pandemic on routine immunization coverage in children under 2 years old in Ontario, Canada: A retrospective cohort study.

BACKGROUND: The COVID-19 pandemic has caused a disruption in childhood immunization coverage around the world. This study aimed to determine the change in immunization coverage for children under 2 years old in Ontario, Canada, comparing time periods pre-pandemic to during the first year of the pandemic. METHODS: Observational retrospective open cohort study, using primary care electronic medical record data from the University of Toronto Practice-Based Research Network (UTOPIAN) database, from January 2019 to December 2020. Children under 2 years old who had at least 2 visits recorded in UTOPIAN were included. We measured up-to-date (UTD) immunization coverage rates, overall and by type of vaccine (DTaP-IPV-Hib, PCV13, Rota, Men-C-C, MMR, Var), and on-time immunization coverage rates by age milestone (2, 4, 6, 12, 15, 18 months). We compared average coverage rates over 3 periods of time: January 2019-March 2020 (T1); March-July 2020 (T2); and August-December 2020 (T3). RESULTS: 12,313 children were included. Overall UTD coverage for all children was 71.0% in T1, dropped by 5.7% (95% CI: -6.2, -5.1) in T2, slightly increased in T3 but remained lower than in T1. MMR vaccine UTD coverage slightly decreased in T2 and T3 by approximately 2%. The largest decreases were seen at ages 15-month and 18-month old, with drops in on-time coverage of 14.7% (95% CI: -18.7, -10.6) and 16.4% (95% CI: -20.0, -12.8) respectively during T2. When stratified by sociodemographic characteristics, no specific subgroup of children was found to have been differentially impacted by the pandemic. CONCLUSION: Childhood immunization coverage rates for children under 2 years in Ontario decreased significantly during the early period of the COVID-19 pandemic and only partially recovered during the rest of 2020. Public health and educational interventions for providers and parents are needed to ensure adequate catch-up of delayed/missed immunizations to prevent potential outbreaks of vaccine-preventable diseases.

SARS-CoV-2 antibodies in Ontario health care workers during and after the first wave of the pandemic: a cohort study.

BACKGROUND: Health care workers have a critical role in the pandemic response to COVID-19 and may be at increased risk of infection. The objective of this study was to assess the seroprevalence of SARS-CoV-2 immunoglobulin G (IgG) antibodies among health care workers during and after the first wave of the pandemic. METHODS: We conducted a prospective multicentre cohort study involving health care workers in Ontario, Canada, to detect IgG antibodies against SARS-CoV-2. Blood samples and self-reported questionnaires were obtained at enrolment, at 6 weeks and at 12 weeks. A community hospital, tertiary care pediatric hospital and a combined adult-pediatric academic health centre enrolled participants from Apr. 1 to Nov. 13, 2020. Predictors of seropositivity were evaluated using a multivariable logistic regression, adjusted for clustering by hospital site. RESULTS: Among the 1062 health care workers participating, the median age was 40 years, and 834 (78.5%) were female. Overall, 57 (5.4%) were seropositive at any time point (2.5% when participants with prior infection confirmed by polymerase chain reaction testing were excluded). Seroprevalence was higher among those who had a known unprotected exposure to a patient with COVID-19 (p < 0.001) and those who had been contacted by public health because of a nonhospital exposure (p = 0.003). Providing direct care to patients with COVID-19 or working on a unit with a COVID-19 outbreak was not associated with higher seroprevalence. In multivariable logistic regression, presence of symptomatic contacts in the household was the strongest predictor of seropositivity (adjusted odds ratio 7.15, 95% confidence interval 5.42-9.41). INTERPRETATION: Health care workers exposed to household risk factors were more likely to be seropositive than those not exposed, highlighting the need to emphasize the importance of public health measures both inside and outside of the hospital.

Association of Age and Pediatric Household Transmission of SARS-CoV-2 Infection.

Importance: As a result of low numbers of pediatric cases early in the COVID-19 pandemic, pediatric household transmission of SARS-CoV-2 remains an understudied topic. Objective: To determine whether there are differences in the odds of household transmission by younger children compared with older children. Design, Setting, and Participants: This population-based cohort study took place between June 1 and December 31, 2020, in Ontario, Canada. Private households in which the index case individual of laboratory-confirmed SARS-CoV-2 infection was younger than 18 years were included. Individuals were excluded if they resided in apartments missing suite information, in households with multiple index cases, or in households where the age of the index case individual was missing. Exposures: Age group of pediatric index cases categorized as 0 to 3, 4 to 8, 9 to 13, and 14 to 17 years. Main Outcomes and Measures: Household transmission, defined as households where at least 1 secondary case occurred 1 to 14 days after the pediatric index case. Results: A total of 6280 households had pediatric index cases, and 1717 households (27.3%) experienced secondary transmission. The mean (SD) age of pediatric index case individuals was 10.7 (5.1) years and 2863 (45.6%) were female individuals. Children aged 0 to 3 years had the highest odds of transmitting SARS-CoV-2 to household contacts compared with children aged 14 to 17 years (odds ratio, 1.43; 95% CI, 1.17-1.75). This association was similarly observed in sensitivity analyses defining secondary cases as 2 to 14 days or 4 to 14 days after the index case and stratified analyses by presence of symptoms, association with a school/childcare outbreak, or school/childcare reopening. Children aged 4 to 8 years and 9 to 13 years also had increased odds of transmission (aged 4-8 years: odds ratio, 1.40; 95% CI, 1.18-1.67; aged 9-13 years: odds ratio, 1.13; 95% CI, 0.97-1.32). Conclusions and Relevance: This study suggests that younger children may be more likely to transmit SARS-CoV-2 infection compared with older children, and the highest odds of transmission was observed for children aged 0 to 3 years. Differential infectivity of pediatric age groups has implications for infection prevention within households, as well as schools/childcare, to minimize risk of household secondary transmission. Additional population-based studies are required to establish the risk of transmission by younger pediatric index cases.

Impact of the COVID-19 pandemic on the provision of routine childhood immunizations in Ontario, Canada.

BACKGROUND: The COVID-19 pandemic has a worldwide impact on all health services, including childhood immunizations. In Canada, there is limited data to quantify and characterize this issue. METHODS: We conducted a descriptive, cross-sectional study by distributing online surveys to physicians across Ontario. The survey included three sections: provider characteristics, impact of COVID-19 on professional practice, and impact of COVID-19 on routine childhood immunization services. Multivariable logistic regression identified factors associated with modification of immunization services. RESULTS: A total of 475 respondents answered the survey from May 27th to July 3rd 2020, including 189 family physicians and 286 pediatricians. The median proportion of in-person visits reported by physicians before the pandemic was 99% and dropped to 18% during the first wave of the pandemic in Ontario. In total, 175 (44.6%) of the 392 respondents who usually provide vaccination to children acknowledged a negative impact caused by the pandemic on their immunization services, ranging from temporary closure of their practice (n = 18; 4.6%) to postponement of vaccines in certain age groups (n = 103; 26.3%). Pediatricians were more likely to experience a negative impact on their immunization services compared to family physicians (adjusted odds ratio [aOR] = 2.64, 95% CI: 1.48-4.68), as well as early career physicians compared to their more senior colleagues (aOR = 2.69, 95% CI: 1.30-5.56), whereas physicians from suburban settings were less impacted than physicians from urban settings (aOR = 0.62, 95% CI: 0.39-0.99). Some of the proposed solutions to decreased immunization services included assistance in accessing personal protective equipment, dedicated centers or practices for vaccination, universal centralized electronic immunization records and education campaigns for parents. CONCLUSIONS: COVID-19 has caused substantial modifications to pediatric immunization services across Ontario. Strategies to mitigate barriers to immunizations during the pandemic need to be implemented in order to avoid immunity gaps that could lead to an eventual increase in vaccine preventable diseases.

Healthcare worker perception of a global outbreak of novel coronavirus (COVID-19) and personal protective equipment: Survey of a pediatric tertiary-care hospital.

OBJECTIVE: In this study, we aimed to capture perspectives of healthcare workers (HCWs) on coronavirus disease 2019 (COVID-19) and infection prevention and control (IPAC) measures implemented during the early phase of the COVID-19 pandemic. DESIGN: A cross-sectional survey of HCWs. PARTICIPANTS: HCWs from the Hospital for Sick Children, Toronto, Canada. INTERVENTION: A self-administered survey was distributed to HCWs. We analyzed factors influencing HCW knowledge and self-reported use of personal protective equipment (PPE), concerns about contracting COVID-19 and acceptance of the recommended IPAC precautions for COVID-19. RESULTS: In total, 175 HCWs completed the survey between March 6 and March 10: 35 staff physicians (20%), 24 residents or fellows (14%), 72 nurses (41%), 14 respiratory therapists (8%), 14 administration staff (8%), and 14 other employees (8%). Most of the respondents were from the emergency department (n = 58, 33%) and the intensive care unit (n = 58, 33%). Only 86 respondents (50%) identified the correct donning order; only 60 (35%) identified the correct doffing order; but the majority (n = 113, 70%) indicated the need to wash their hands immediately prior to removal of their mask and eye protection. Also, 91 (54%) respondents felt comfortable with recommendations for droplet and/or contact precautions for routine care of patients with COVID-19. HCW occupation and concerns about contracting COVID-19 outside work were associated with nonacceptance of the recommendations (P = .016 and P = .036 respectively). CONCLUSION: As part of their pandemic response plans, healthcare institutions should have ongoing training for HCWs that focus on appropriate PPE doffing and discussions around modes of transmission of COVID-19.

Visitor Restriction Policy on Pediatric Wards During Novel Coronavirus (COVID-19) Outbreak: A Survey Study Across North America.

Visitor restriction policies in pediatric wards during the novel coronavirus (COVID-19) outbreak are variable. Among 36 hospitals that responded to our survey, 97% allowed at least 1 visitor, with 67% restricting to 1 caregiver. Sixty-nine percent required the visitor to wear personal protective equipment and only 19% allowed non-household visitors.

Effect of moist heat reprocessing of N95 respirators on SARS-CoV-2 inactivation and respirator function.

BACKGROUND: Unprecedented demand for N95 respirators during the coronavirus disease 2019 (COVID-19) pandemic has led to a global shortage of these masks. We validated a rapidly applicable, low-cost decontamination protocol in compliance with regulatory standards to enable the safe reuse of N95 respirators. METHODS: We inoculated 4 common models of N95 respirators with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and evaluated viral inactivation after disinfection for 60 minutes at 70°C and 0% relative humidity. Similarly, we evaluated thermal disinfection at 0% to 70% relative humidity for masks inoculated with Escherichia coli. We assessed masks subjected to multiple cycles of thermal disinfection for structural integrity using scanning electron microscopy and for protective functions using standards of the United States National Institute for Occupational Safety and Health for particle filtration efficiency, breathing resistance and respirator fit. RESULTS: A single heat treatment rendered SARS-CoV-2 undetectable in all mask samples. Compared with untreated inoculated control masks, E. coli cultures at 24 hours were virtually undetectable from masks treated at 70°C and 50% relative humidity (optical density at 600 nm wavelength, 0.02 ± 0.02 v. 2.77 ± 0.09, p < 0.001), but contamination persisted for masks treated at lower relative humidity. After 10 disinfection cycles, masks maintained fibre diameters similar to untreated masks and continued to meet standards for fit, filtration efficiency and breathing resistance. INTERPRETATION: Thermal disinfection successfully decontaminated N95 respirators without impairing structural integrity or function. This process could be used in hospitals and long-term care facilities with commonly available equipment to mitigate the depletion of N95 masks.