Are healthcare workers more likely than the general population to consult in primary care for an influenza-like illness? Results from a case-control study

Abstract

Background: Healthcare workers are at increased risk of contracting influenza. However, existing studies do not differentiate professional categories or domains of the healthcare system that are most at risk. Methods: This case-control study compared proportions of patients with professional activity in the healthcare system between cases consulting their primary care physician for an influenza-like illness (ILI) and controls from the general patient population of the same practices of the Swiss sentinel network. Influenza was confirmed by rRT-PCR in a subset of practices. Analysis used a mixed logistic regression model, including age and sex as potential confounders. Results: During the 2018/2019 influenza surveillance season, out of 4287 ILI cases and 28 561 controls reported in 168 practices, 235 (5.5%), respectively 872 (3.1%), were active in the healthcare system. After adjustment, being active in health care increased the odds of consulting for an ILI (OR 1.66, 95% CI 1.40-1.97). The association was strongest for physicians and nursing aides. In terms of work setting, odds of consulting for ILI were increased for professionals of almost all healthcare settings except home-based care. Conclusion: Individuals active in the healthcare system were more likely to consult their primary care physician for an influenza-like illness than for another reason, compared with individuals not active in the healthcare system. These results warrant further efforts to understand influenza transmission in the healthcare system at large.