Objectives Shortly before the COVID-19 pandemic, the Workplace Safety and Insurance Board of Ontario, Canada, launched the Health and Safety Excellence program (HSEp), a new voluntary occupational health and safety management system (OHSMS) program. This study conducted a prospective evaluation for the impact of HSEp participation on injury rate reduction during an ongoing pandemic.

Methods A difference-in-differences study design with a hybrid matching approach was used to evaluate HSEp’s effectiveness in reducing lost-time injury rates with and without COVID-19 claims among participating firms compared with similar non-participating firms. The analysis was stratified by enrollment cohort, industry, firm size, and prior OHSMS experience.

Results A total of 1680 matched HSEp firms were followed for 48 months. Some evidence of an effect on lost-time injury rates was observed, particularly after excluding COVID-19 claims. Non-COVID-19 lost-time rate reductions were pronounced among firms that enrolled later [incidence rate ratio (IRR) 0.89, 95% confidence interval (CI) 0.82–0.98], manufacturing firms (IRR 0.81, CI 0.68–0.96), larger firms (IRR 0.92, CI 0.85–0.99), and firms that had progressed through the program (IRR 0.91, CI 0.83–0.98). However, the reductions were not apparent among healthcare and construction companies or smaller firms.

Conclusions Although the evidence of overall injury rate reductions is limited, emerging evidence suggests that participating in HSEp is associated with reductions in non-COVID-19 injuries in certain contexts. These findings suggest that the OHSMS program performance was affected by the pandemic, and accounting for this was crucial in assessing an intervention effect.

Key terms Canada; COVID-19; difference-in-difference; intervention; occupational health and safety; occupational health and safety management system; pandemic; workplace injury

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