Background: Essential workers, including those working in healthcare and education, are at higher risk of exposure to communicable diseases, including SARS-CoV-2. Reducing the rates of infection is important for their personal health and for the ongoing safe operation of essential services.
Methods: Data from participants in two prospective cohort studies who tested positive for SARS-CoV-2 in 2020 through 2023 were used to determine whether vaccination against SARS-CoV-2 is associated with the severity of symptoms in working-age adults.
Results: SARS-CoV-2-positive tests (N = 3757) were reported by 3093 participants (mean: 1.2 per person); 1229 (33%) illnesses did not interfere with regular activities, 1926 (51%) made participants too unwell for regular activities, and 602 (16%) required participant bed rest. Compared with vaccine receipt more than 12 months earlier, receipt within six months of an infection was associated with lower risk ratios for more severe illness (too unwell: 0.69 and bed rest: 0.67) compared with being able to conduct regular activities. More recent vaccination was also associated with lower odds reporting of systemic symptoms (fever, myalgia, arthralgia) and fewer solicited symptoms.
Conclusion: Staying current with COVID-19 vaccinations should continue to be recommended since receiving a recent immunization lessened the severity of illness. Also, as symptoms of COVID-19 are now largely similar to other respiratory viruses, practitioners need to use this evidence to inform diagnostic testing and return-to-work policies.
Keywords: COVID-19 vaccines; Canada; adult; illness; symptoms.