Flu or Jab, Is It a Hard Decision? Boosting Older Adults' Influenza Vaccination through Text-based Nudge and Lottery

Last registered on December 01, 2023
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Pre-Trial

Trial Information

General Information

Title
Flu or Jab, Is It a Hard Decision? Boosting Older Adults' Influenza Vaccination through Text-based Nudge and Lottery
RCT ID
AEARCTR-0012450
Initial registration date
November 16, 2023

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
December 01, 2023, 4:18 AM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

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Primary Investigator

Name
Mengna Luan
Affiliation
Southwestern University of Finance and Economics
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Other Primary Investigator(s)

PI Name
Yiming Xia
PI Affiliation
Southwestern University of Finance and Economics
PI Name
Pedro Carneiro
PI Affiliation
University College London

Additional Trial Information

Status
On going
Start date
2023-10-12
End date
2024-05-31
Keywords
Behavior, Health
Additional Keywords
Vaccinations
JEL code(s)
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
We are conducting an RCT on encouraging Influenza vaccinations among older adults in poor regions in China. We recruit participants following the three criteria: (1) aged 60 or above; (2) not vaccinated against the flu yet for this year; (3) eligible for local vaccine policy. We randomize participants equally into 3 three arms, (1) control, (2) receiving a modified version of the most effective text-based nudges in Milkman, et al. (2021), and (3) receiving a lottery of getting vouchers for flu vaccination. We collect survey data before and after the nudges or lottery as well as administrative data on vaccination, other health-related behaviors and outcomes, and health expenditure for program evaluation.
External Link(s)

Registration Citation

Citation
Carneiro, Pedro, Mengna Luan and Yiming Xia. 2023. "Flu or Jab, Is It a Hard Decision? Boosting Older Adults' Influenza Vaccination through Text-based Nudge and Lottery." AEA RCT Registry. December 01. https://doi.org/10.1257/rct.12450-1.0
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Experimental Details

Interventions

Intervention(s)
1. text-based nudges

2. a lottery with an equal chance to get a voucher for various amounts.

3. For about 900 subsamples, we have a cross-cutting design with information on the costs of the flu among older adults.
Intervention Start Date
2023-10-12
Intervention End Date
2023-11-30

Primary Outcomes

Primary Outcomes (end points)
Vaccination decisions, Health-related outcomes
Primary Outcomes (explanation)
Vaccination decisions - we have objective one from administrative records on flu vaccination and the self-reports of willingness to get a flu vaccine collected in the survey (dummy + probability of getting it)
Health-related outcomes: whether receive outpatient care, whether receive inpatient care, total inpatient expenditure and itemized expenses (if available), total outpatient expenditure;

Secondary Outcomes

Secondary Outcomes (end points)
Donations, reasons for taking vaccine or not, subjective well-being and trust, body check
Secondary Outcomes (explanation)
donation: we ask them about whether to donate some of the vouchers/awards.
reasons for taking: why take the flu shot? why not?
trust: trust the vaccine/healthcare system
body check: whether taking the free physical exams for older adults, body weight, blood pressure, blood lipids, blood sugar

Experimental Design

Experimental Design
We integrate the experiments into a survey conducted by enumerators who collect baseline data and implement the interventions, and we collect follow-up data from different sources.
We conducte the experiment in two strata and randomize the intervention within each stratum.
The cross-cutting randomization is independent of two main interventions
Experimental Design Details
Not available
Randomization Method
Randomization is conducted by a computer or smartphone using the online survey software.
Randomization Unit
Individual
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
1200 older adults
Sample size: planned number of observations
1200 older adults
Sample size (or number of clusters) by treatment arms
400 control, 400 nudges, and 400 lottery
cross-cutting gives 450 control and 450 cost information
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
vaccination, N per group=325 (5%) and 260 (10%), control 8%, and treatment 15%
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
West China 4th Hospital and West China School of Public Health, Sichuan University
IRB Approval Date
2023-09-27
IRB Approval Number
Gwll2023220
Analysis Plan