How can influenza vaccination be promoted among adults in China? Evidence from a discrete choice experiment

The influenza vaccination rate remains low in China, especially among younger adults aged 18 to 60 years old. This study aimed to estimate public preferences for influenza vaccines and to identify attributes that maximize vaccination rates.

This study utilized a discrete choice experiment to estimate the relative importance (RI) of seven influenza vaccine-related attributes, including effectiveness, protection duration, risk of severe side effects, recommendation source, manufacturer's location, vaccination site, and out-of-pocket cost. Participants were recruited from eight community healthcare centers in four cities and surveys were conducted face-to-face. A mixed logit model was employed to estimate the preference coefficient and marginal willingness to pay (mWTP) and to predict the uptake rate. The interaction effects were included to explore how individual characteristics might influence preference heterogeneity.

A total of 802 participants completed the survey, with 618 included in the data analysis. The analysis showed that six of the seven attributes significantly influenced vaccination preferences, with the exception of vaccination site. Participants assigned the highest value to the risk of severe side effects (RI = 31.50%), followed by out-of-pocket costs (RI = 24.46%) and effectiveness (RI = 20.39%). The highest mWTP ($30.62) was observed when the risk of severe side effects was reduced from 5/100,000 to 1/100,000. Participants' preferences varied depending on their age, education, residence, occupation, and income. By providing a cost-free influenza vaccine and maintaining all other attributes at the baseline, a higher vaccination rate of up to 77.9% will be achieved.

Vaccine side effects, cost, and effectiveness were key determinants of influenza vaccine preference. Inclusion of the influenza vaccine in the national immunization program, making it freely available, holds promise for increasing vaccination rates.