Impacts of free vaccination policy and associated factors on influenza vaccination behavior of the elderly in China: A quasi-experimental study

Abstract

Background: Chinese elders are under high threats of seasonal influenza, while showing low influenza vaccination coverage comparing with other countries. The study explored the impacts of free vaccination policy and associated factors on influenza vaccination behavior of the elderly in Zhejiang Province, China, offering a guidance of interventions for protecting elders from seasonal influenza.

Methods: 1210 elders ≥60 years were conveniently recruited between July and September of 2019. 607 of them were sampled from 6 counties with free vaccination policy, while the other 603 elderly people were sampled from another 6 comparable counties without the policy. A self-reported questionnaire, involving socio-democratic information, physical status and behavior, influenza knowledge, vaccination awareness, relatives of healthcare workers, and vaccination behavior, was completed by elders under supports of research assistants. Chi-square tests and logistic regression analyses were performed to explore the impacts of research factors.

Results: A total of 464 (38.3%, 95%CI: 36.9-39.7%) elders claimed that they got vaccinated, and the vaccination coverages of elders in the counties with and without free vaccination policy were 68.4% (95%CI: 64.7-72.1%) and 8.1% (95%CI: 5.9-10.3%), respectively. Protective and risk factors of vaccination behavior were identified, including free vaccination policy (OR_step = 27.29, 95%CI: 18.69-39.82), positive vaccination awareness (OR_step = 7.93, 95%CI: 5.50-11.43), catching cold frequently (OR_step = 2.00, 95%CI: 1.32-3.05), and having relatives of healthcare workers (OR_step = 0.56, 95%CI: 0.34-0.93). Age, education level, monthly income, family structure, physical status, and influenza knowledge were significantly associated with vaccination behavior. Having relatives of healthcare workers may indirectly affect vaccination behavior through vaccination awareness.

Conclusions: Free vaccination policy plays the most fundamental role of improving vaccination coverage among studied factors. To protect elders from seasonal influenza, effective measurements, such as issuing free vaccination policy, enriching influenza knowledge, and guiding positive vaccination awareness for both elders and healthcare professionals are recommended to be included into influenza immunization strategies.

Keywords: Free vaccination policy; Influenza vaccine; Quasi-experimental study; Seasonal influenza; Vaccination behavior; Vaccination coverage.