Household Secondary Attack Rate of COVID-19 among Healthcare Workers and Related Factors

BACKGROUND: The risk for transmission of COVID-19 to people in close contact with infected people, especially healthcare workers, has not been well estimated. Therefore the present study was conducted to assess the household secondary attack rate (SAR) of COVID-19 among healthcare workers and related factors. MATERIALS AND METHODS: The present prospective case-ascertained study was conducted on 202 healthcare workers with confirmed COVID-19 in Hamadan, diagnosed from March 1, 2020, to August 20, 2020. For households with close contact with the index case, RT-PCR was performed regardless of symptoms. We defined SAR as the proportion of secondary cases from the total contacts that live in the index case household. SAR was reported as a percentage and 95% confidence interval (CI). Multiple logistic regression was performed to explore the predictors of COVID-19 transmission of index cases to their households. RESULTS: We found 36 secondary cases out of 391 household contacts with laboratory confirmation (RT-PCR), representing a household SAR of 9.2% (95% CI: 6.3, 12.1). Among factors related to the family member, female gender (OR: 2.9, 95% CI: 1.2, 6.9), being the patient's spouse (OR: 2.2, 95% CI: 1.0, 4.6), and living in the apartment (OR: 2.78, 95% CI: 1.24, 6.23), and among factors related to index cases, hospitalization (OR: 5.9, 95% CI: 1.3, 26.9) and caught (OR: 2.4, 95% CI: 1.1, 5.2) were the significant predictors of disease transmission to other family members (P<0.05). CONCLUSION: The findings of this study suggest that the SAR is remarkable in household contacts of infected healthcare workers. Some characteristics of family members of the index case, including female gender, being the patient's spouse, and living in the apartment, and some characteristics of the index case, including hospitalization and caught, were associated with the increased SAR.