# Pay-it-forward intervention increased pneumococcal vaccine uptake among older adults in China: a randomized controlled trial

## TL;DR

A pay-it-forward cost-sharing program significantly increased pneumococcal and flu vaccine uptake among older adults in China compared to standard self-paid options.

## Contribution

This study introduces and evaluates a novel pay-it-forward intervention to improve vaccine uptake in older adults.

## Key findings

- The pay-it-forward group had a 70.9% pneumococcal vaccine uptake versus 13.5% in the standard-of-care group.
- Participants in the pay-it-forward group showed higher vaccine confidence and lower economic cost per vaccination.
- The intervention also increased influenza vaccine uptake and successful vaccine referrals.

## Abstract

Pneumococcal vaccination reduces morbidity and mortality among older adults, yet coverage remains suboptimal in China. This study aimed to assess the effectiveness of a pay-it-forward intervention (covering two-thirds of the pneumococcal vaccination cost and offering the option to donate) in increasing pneumococcal vaccination among older adults (aged 60 years or older) in China, compared to standard-of-care self-paid vaccination.

We used block randomization (block size = 4) to assign participants to a pay-it-forward arm and a standard-of-care arm in a 1:1 ratio. The primary outcome was pneumococcal vaccination. Secondary outcomes included influenza vaccine uptake, vaccine confidence, successful vaccine referral, and cost-effectiveness. Logistic regression analysis was used to compare PPSV-23 and influenza vaccination coverage and vaccine confidence between the two groups. The cost-effectiveness of the interventions was assessed using a micro-costing approach from the healthcare provider’s perspective.

From January to September 2024, 221 older adults were randomized (110 in the pay-it-forward group and 111 in the standard-of-care group). Pneumococcal and influenza vaccine uptake were significantly higher in the pay-it-forward arm (70.9% and 30.0%) than in the standard-of-care arm (13.5% and 17.1%), with adjusted odds ratios of 17.20 (95% CI, 8.39–37.60) and 2.29 (95% CI, 1.17–4.65). The pay-it-forward group also exhibited greater confidence in the safety (4.29, 95% CI, 1.78–11.50), importance (5.15, 95% CI, 2.05–14.60), and effectiveness (7.14, 95% CI, 2.36–27.50) of the vaccine than that in the standard-of-care group. The pay-it-forward group had a higher successful vaccine referral rate (15.5% vs. 10.8%) and had a lower economic cost per person vaccinated (US $95.67 vs. US $278.56) compared with the standard-of-care arm.

Our findings demonstrate that the pay-it-forward intervention significantly enhances pneumococcal and influenza vaccination coverage and improves vaccine confidence among the older adults. This study highlights the potential of the pay-it-forward intervention as an effective means to boost health service utilization.

2024–01-03, Chinese Clinical Trial Registry, ChiCTR2400079410.

The online version contains supplementary material available at 10.1186/s12916-026-04624-2.