Climate change and health: rethinking public health messaging for wildfire smoke and extreme heat co-exposures.

With the growing climate change crisis, public health agencies and practitioners must increasingly develop guidance documents addressing the public health risks and protective measures associated with multi-hazard events. Our Policy and Practice Review aims to assess current public health guidance and related messaging about co-exposure to wildfire smoke and extreme heat and recommend strengthened messaging to better protect people from these climate-sensitive hazards. We reviewed public health messaging published by governmental agencies between January 2013 and May 2023 in Canada and the United States. Publicly available resources were eligible if they discussed the co-occurrence of wildfire smoke and extreme heat and mentioned personal interventions (protective measures) to prevent exposure to either hazard. We reviewed local, regional, and national governmental agency messaging resources, such as online fact sheets and guidance documents. We assessed these resources according to four public health messaging themes, including (1) discussions around vulnerable groups and risk factors, (2) symptoms associated with these exposures, (3) health risks of each exposure individually, and (4) health risks from combined exposure. Additionally, we conducted a detailed assessment of current messaging about measures to mitigate exposure. We found 15 online public-facing resources that provided health messaging about co-exposure; however, only one discussed all four themes. We identified 21 distinct protective measures mentioned across the 15 resources. There is considerable variability and inconsistency regarding the types and level of detail across described protective measures. Of the identified 21 protective measures, nine may protect against both hazards simultaneously, suggesting opportunities to emphasize these particular messages to address both hazards together. More precise, complete, and coordinated public health messaging would protect against climate-sensitive health outcomes attributable to wildfire smoke and extreme heat co-exposures.

COVID-19 hospitalisations in immunocompromised individuals in the Omicron era: a population-based observational study using surveillance data in British Columbia, Canada.

Background: People with immune dysfunction are at higher risk of severe outcomes from COVID-19 infection, but relatively little epidemiologic information is available for mostly vaccinated population in the Omicron era. This population-based study compared relative risk of breakthrough COVID-19 hospitalisation among vaccinated people identified as clinically extremely vulnerable (CEV) vs non-CEV individuals before treatment became more widely available. Methods: COVID-19 cases and hospitalisations reported to the British Columbia Centre for Disease Control (BCCDC) between January 7, 2022 and March 14, 2022 were linked with data on their vaccination and CEV status. Case hospitalisation rates were estimated across CEV status, age groups and vaccination status. For vaccinated individuals, risk ratios for breakthrough hospitalisations were calculated for CEV and non-CEV populations matched on sex, age group, region, and vaccination characteristics. Findings: Among CEV individuals, a total of 5591 COVID-19 reported cases were included, among which 1153 were hospitalized. A third vaccine dose with mRNA vaccine offered additional protection against severe illness in both CEV and non-CEV individuals. However, 2- and 3-dose vaccinated CEV population still had a significantly higher relative risk of breakthrough COVID-19 hospitalisation compared with non-CEV individuals. Interpretation: Vaccinated CEV population remains a higher risk group in the context of circulating Omicron variant and may benefit from additional booster doses and pharmacotherapy. Funding: BC Centre for Disease Control and Provincial Health Services Authority.

Transmission dynamics of SARS-CoV-2 in British Columbia's largest school district during the second half of the 2020-2021 school year.

OBJECTIVES: To determine the extent and characteristics of in-school transmission of SARS-CoV-2 and determine risk factors for in-school acquisition of COVID-19 in one of Canada's largest school districts. METHODS: We conducted a retrospective chart review of all reportable cases of COVID-19 who attended a kindergarten-Grade 12 (K-12) school within the study area between January and June of the 2020-2021 school year. The acquisition source was inferred based on epidemiological data and, when available, whole genome sequencing results. Mixed effects logistic regression was performed to identify risk factors independently associated with in-school acquisition of COVID-19. RESULTS: Overall, 2877 cases of COVID-19 among staff and students were included in the analysis; of those, 9.1% had evidence of in-school acquisition. The median cluster size was two cases (interquartile range: 1). Risk factors for in-school acquisition included being male (adjusted odds ratio [aOR]: 1.59, 95% confidence interval [CI]: 1.17-2.17), being a staff member (aOR: 2.62, 95% CI: 1.64-4.21) and attending or working in an independent school (aOR: 2.28, 95% CI: 1.13-4.62). CONCLUSION: In-school acquisition of COVID-19 was uncommon during the study period. Risk factors were identified in order to support the implementation of mitigation strategies that can reduce transmission further.

RéSUMé: OBJECTIFS: Déterminer l'étendue et les caractéristiques de la transmission de la SRAS-CoV-2 en milieu scolaire, et déterminer les facteurs de risque de l'acquisition de la COVID-19 dans l'un des plus larges arrondissements scolaires du Canada. MéTHODES: Nous avons mené un examen rétrospectif des dossiers de tous les cas signalés de COVID-19 ayant fréquenté une école de niveau élémentaire, primaire ou secondaire dans la zone à l'étude entre janvier et juin de l'année scolaire 2020-2021. La source d'acquisition était inférée sur la base des données épidémiologiques et, lorsque disponibles, les résultats de séquençage du génome entier. Nous avons eu recours à des régressions logistiques multiniveaux pour identifier les facteurs indépendamment associés avec l'acquisition de la COVID-19 en milieu scolaire. RéSULTATS: Au total, 2 877 cas de COVID-19 parmi les employés et les élèves ont été inclus dans l'analyse; de ceux-ci, 9,1 % avaient acquis l'infection en milieu scolaire. La grosseur médiane des agrégats était de deux cas (écart interquartile : 1). Les risques facteurs de l'acquisition en milieu scolaire incluaient le fait d'être de sexe masculin (rapport de cotes ajusté [RCa] : 1,59, intervalle de confiance [IC] de 95% : 1,17-2,17), être un membre du personnel (RCa : 2,62, IC de 95% : 1,64-4,21) et fréquenter ou travailler dans une école indépendante (RCa : 2,28, IC de 95% : 1,13-4,62). CONCLUSION: Nos résultats suggèrent que l'acquisition de la COVID-19 en milieu scolaire était peu commune pendant la période d'étude. Des facteurs de risque ont été identifiés afin de supporter l'implémentation de mesures de contrôle pouvant réduire davantage la transmission.