Relative risks of COVID-19 fatality between the first and second waves of the pandemic in Ontario, Canada.

ABSTRACT

OBJECTIVES: To examine whether the case fatality rate (CFR) of COVID-19 decreased over time and whether the COVID-19 testing rate is a driving factor for the changes if the CFR decreased. METHODS: Analyzing COVID-19 cases, deaths and tests in Ontario, Canada, we compared the CFR between the first wave and the second wave across 26 public health units in Ontario. We also explored whether a high testing rate was associated with a large CFR decrease. RESULTS: The first wave CFR ranged from 0.004 to 0.146, whereas the second wave CFR ranged from 0.003 to 0.034. The pooled RR estimate of second wave COVID-19 case fatality, compared with first wave, was 0.24 (95% CI 0.19-0.32). Additionally, COVID-19 testing percentages were not associated with the estimated relative risk (P=0.246). CONCLUSIONS: The COVID-19 CFR decreased significantly in Ontario during the second wave, and COVID-19 testing was not a driving factor for this decrease.