Influenza vaccination uptake and its determinants during the 2019-2020 and early 2020-2021 flu seasons among migrants in Shanghai, China: a cross-sectional survey.

Influenza vaccination coverage has generally been low in mainland China. However, few studies have attempted to measure influenza vaccination coverage among internal migrants in China who are at an increased risk of influenza infections. This study assessed influenza vaccination coverage and the factors associated with vaccination uptake among internal migrants in Shanghai, China. We conducted a cross-sectional online survey among a sample of migrants residing in Shanghai during November 1-20, 2020, to investigate vaccination uptake during the 2019-20 and early 2020-21 flu seasons (September to November 2020). Multivariable logistic regression was used to examine the factors associated with influenza vaccination uptake for the two flu seasons. About a quarter, 26.3%, and 24.4% of respondents reported receiving an influenza vaccination during the 2019-20 and early 2020-2021 flu seasons, respectively. Respondents who were divorced or widowed, had more household members (2 or ≥ 3), and considered themselves in good health were more likely to receive an influenza vaccine, regardless of the season. Respondents who perceived that they were highly susceptible to influenza and COVID-19 and those who reported ever consulting a medical professional about COVID-19 were more likely to have received a flu vaccination in the early 2020-21 flu season. The uptake of influenza vaccination among internal migrants in Shanghai was suboptimal. We found a range of factors linked to influenza vaccination uptake, pointing to the need for more in-depth evaluations on the underlying reasons driving the vaccination uptake among vulnerable populations in China, especially during the COVID-19 pandemic.