Education, Immigration and HPV Vaccination: an Informational Randomized Trial

Last registered on January 27, 2022

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Pre-Trial

Trial Information

General Information

Title

Education, Immigration and HPV Vaccination: an Informational Randomized Trial

RCT ID

AEARCTR-0007668

Initial registration date

August 17, 2021

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

August 19, 2021, 11:06 AM EDT

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

Last updated

January 27, 2022, 11:26 AM EST

Last updated is the most recent time when changes to the trial's registration were published.

Locations

Country

Sweden

Region

Stockholm County

Primary Investigator

Name

Lisen Arnheim Dahlström

Affiliation

Karolinska Institutet

Contact Primary Investigator

Other Primary Investigator(s)

PI Name

Alice Dominici

PI Affiliation

European University Institute

Contact Investigator

Additional Trial Information

Status

On going

Start date

2021-06-14

End date

2022-10-31

Keywords

Behavior, Health

Additional Keywords

Information framing, vaccines

JEL code(s)

Secondary IDs

NCT04905030

Prior work

This trial does not extend or rely on any prior RCTs.

Abstract

Counteracting misinformation on childhood vaccines remains a priority for
public health in industrialized countries. Previous research showed that
misinformation-induced vaccine hesitancy particularly concerns very highly
or very lowly educated parents, and, especially in Europe, specific groups of
immigrants. Misinformation framing directly targets specific sub-population
of parents by exploiting different cognitive biases, and specific concerns
based on cultural norms: we aim at testing the effectiveness of similar framing
techniques applied to positive information on the HPV vaccine by conducting a stratified
Randomized Controlled Trial in Stockholm, Sweden. We randomize emotionally
and scientifically/statistically framed information addressing the specific
concerns reported by the epidemiological literature, and test whether they improve HPV vaccination uptake and reduce common vaccines misconceptions.

External Link(s)

Registration Citation

Citation

Arnheim Dahlström, Lisen and Alice Dominici. 2022. "Education, Immigration and HPV Vaccination: an Informational Randomized Trial." AEA RCT Registry. January 27. https://doi.org/10.1257/rct.7668-1.1

Sponsors & Partners

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Experimental Details

Interventions

Intervention(s)

Intervention Start Date

2021-06-14

Intervention End Date

2021-08-31

Primary Outcomes

Primary Outcomes (end points)

1. Actual decision to vaccinate child against HPV
Investigators will assess if there are significant differences in the frequency of parents who decide to vaccinate across
treatment arms, within each stratum
[This outcome is extracted from national vaccination registers in November 2021]
2. Self-reported beliefs about false risks of the HPV vaccine, and trust in health authorities
The investigators will examine whether across treatment groups, within strata, parents show different degrees of
agreement with false statements concerning the risks of HPV
[Time Frame: outcome will be assessed in the initial survey administered right after the informational intervention (June-August 2021) and
in the endline survey (November 2021)]

Primary Outcomes (explanation)

Beliefs about false risks of vaccines: we assess the agreement with the following statements on a 5-points Likert scale:
-Vaccines weaken and overload the immune system
-Vaccines can cause the disease against which they protect
-Vaccines can produce serious side effects
We will use individual measures and their arithmetic mean.
We also assess self-reported trust in health authorities by asking agreement with the following statement:
- I trust the opinion of health professionals and health authorities about vaccines

Secondary Outcomes

Secondary Outcomes (end points)

Secondary Outcomes (explanation)

Experimental Design

Randomization at the individual level within strata, defined by immigration status and education level.

Experimental Design Details

Randomization Method

By computer, performed by the implementation partner (Statistics Sweden, i.e. the national Swedish statistics bureau)

Randomization Unit

Individual (i.e. mother)

Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters

7500 invited, 2500 expected participants. Details in attachment

Sample size: planned number of observations

7500 invited, 2500 expected participants. Details in attachment

Sample size (or number of clusters) by treatment arms

Within each stratum, we expect 500 actual participants, divided as follows: 120 pure placebo (C), 190 emotional framing (T1), 190 statistical/scientific framing (T2). i.e. of the initial 7500 invited subjects, 38% are randomized to T1, 38% to T2 and the remaining 24% to C.
Details in attachment

Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Details in attachment

Supporting Documents and Materials

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