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

ABSTRACT

ImportanceAccurate understanding of COVID pandemic during the first viral wave in Canada could help prepare for future epidemic waves. ObjectiveTo track the early course of the pandemic by examining self-reported COVID symptoms over time before testing became widely available. DesignAdults 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. SettingA 20-item internet survey. Participants14,408 adults age 18 years of age. ExposuresThe 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." ResultsIn 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 RelevanceThis 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.