A national study of self-reported COVID symptoms during the first viral wave in Canada

Tang, X.; Gelband, H.; Lam, T.; Nagelkerke, N.; Reid, A.; Jha, P.; Investigators, Action to beat Coronavirus Study

Importance: Accurate understanding of COVID pandemic during the first viral wave in Canada could help prepare for future epidemic waves. Objective: To track the early course of the pandemic by examining self-reported COVID symptoms over time before testing became widely available. Design: Adults from the nationally representative Angus Reid Forum were randomly invited to complete an online survey in May/June 2020. The study is a part of the Action to Beat Coronavirus antibody testing study. Setting: A 20-item internet survey. Participants: 14,408 adults age 18 years of age. Exposures: The months that respondents and any household members first experienced various respiratory, neurological, sleep, skin or gastric symptoms. Main Outcomes and Measure: COVID symptom-positive, defined as fever (or fever with hallucinations) plus at least one of difficulty breathing, a dry severe cough, loss of smell or COVID toe. Results: In total, 14,408 panel members (48% male and 52% female) completed the survey. Despite overrepresentation of higher levels of education, the prevalence of obesity, smoking, diabetes and hypertension were similar to national census and health surveys. A total of 811 (5.6%) were COVID symptom-positive; highest rates were at ages 18-44 years (8.3% among), declining at older ages. Females had higher odds of reporting COVID symptoms (OR = 1.32, 95%CI 1.11-1.56) as did visible minorities (OR = 1.74, 1.29-2.35). COVID symptom positivity for respondents and their household members peaked in March (OR = 1.93, 95% CI = 1.59-2.34 compared to earlier months). Conclusions and Relevance: This study enhances our current understanding of the progression of the COVID epidemic in Canada, with few laboratory-confirmed cases in January and February, peaking in April. The results suggest substantial viral transmission in March, before widespread testing began, and a gradual decline in cases since May.