question: BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has been enormously disruptive and harmful to people around the world, but its impact on other illnesses and injuries has been more variable. To evaluate the ramification of infectious disease outbreaks on major traumatic injuries, we compared changes in the incidence of major trauma cases during the 2003 Severe Acute Respiratory Syndrome (SARS) period with COVID-19 in 2020. METHODS: Data were analyzed from the trauma registry of a major, tertiary-care teaching hospital in Hong Kong. Patients presenting with major traumatic injuries during the first six months of 2001–03 and 2018–20 were retrieved for analysis. Patient characteristics, injury mechanism, admitting service, and emergency department (ED)/hospital lengths of stay (LOS) were recorded. Raw and adjusted survival rates (using the modified Trauma Injury Severity Score (TRISS)) were recorded. RESULTS: The number of trauma cases fell dramatically during 2003 and 2020 compared with previous years. In both 2003 and 2020, the number of trauma registry patients fell by 49% in April (compared to the preceding reference years of 2001/02 and 2018/19, respectively). Patient characteristics, treatments, and outcomes were also different during the outbreak years. Comparing 2003 to 2020 relative to their respective reference baselines, the percentages of injuries that happened at home, patients without co-morbidities, and patients' mean age all increased in 2003 but decreased in 2020. Work-place injuries drastically dropped in 2003, but not in 2020. Average ED LOS dropped in 2003 by 36.4 min (95% CI 12.5, 60.3) but declined by only 14.5 min (95% CI -2.9, 32.1) in 2020. Both observed and expected 30-day mortality declined in 2020 vs. 2003 (observed 4.5% vs. 11.7%, p = 0.001, OR 0.352, 95% CI 0.187, 0.661) (expected 4.5% vs 11.6%, p = 0.002, OR 0.358, 95% CI 0.188, 0.684). CONCLUSION: Major trauma cases dropped by half during both the peak of the 2003 SARS and 2020 COVID-19 pandemics in Hong Kong, suggesting a trend for future pandemic planning. If similar findings are seen at other trauma centers, proactive personnel and resource allocations away from trauma towards medical emergency systems may be more appropriate for future pandemics.