Clinical Trial Details
— Status: Enrolling by invitation
Administrative data
NCT number |
NCT04905030 |
Other study ID # |
HPVRCT01225 |
Secondary ID |
|
Status |
Enrolling by invitation |
Phase |
N/A
|
First received |
|
Last updated |
|
Start date |
April 28, 2021 |
Est. completion date |
January 14, 2022 |
Study information
Verified date |
June 2021 |
Source |
Karolinska Institutet |
Contact |
n/a |
Is FDA regulated |
No |
Health authority |
|
Study type |
Interventional
|
Clinical Trial Summary
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: this project aims at testing the effectiveness of similar framing
techniques applied to positive information on the HPV vaccine by conducting a Randomized
Controlled Trial in Stockholm, Sweden. It randomizes emotionally and
scientifically/statistically framed information addressing the specific concerns reported by
previous literature.
Description:
In Europe, non-European immigrants display lower vaccination take-up than natives, a higher
prevalence of STDs, and lower usage of publicly-funded treatments. Therefore, migrants (and
especially women) face worse preventable health issues. Qualitative research suggests that
migrants' lower take-up might be due to culturally founded concerns, which are then exploited
and targeted by anti-vax information. These are adverse effects on fertility and, in the case
of the HPV vaccine, which is administered at a very young age to prevent a
sexually-transmissible infection, on reputational concerns related to incentivizing
pre-marital sexual activity. Existing literature also investigates parental education as an
alternative explanation to vaccines' mistrust, finding mixed evidence which suggests a
non-linear relationship between education level and willingness to vaccinate children. In
particular, qualitative research highlights that targeted misinformation addresses
emotionally charged contents to lowly educated parents, and pseudo-scientific content to
highly educated parents.
In this study, 7500 mothers of children (girls and boys) who are due to be offered the HPV
vaccine in fall 2021 within the Swedish national vaccination program are randomly sampled.
Mothers are stratified according to immigration status, and are sampled from the entire
relevant population through Swedish population registers. There are 5 strata: (i) Mothers
were born in Iran, Iraq, Afghanistan, Somalia, Eritrea (irrespective of education) (N=2500);
(ii) Mothers born in Sweden and have attended at most 3 years of high school (N=1600); (iii)
Mothers born in Sweden and have attended more than 3 years of high school and have not
attended any university (N=1400); (iv) Mothers born in Sweden and have achieved at most
undergraduate education (N=1000); (v) Mothers born in Sweden with graduate education after
obtaining an undergraduate degree (N=1000). Sample sizes are chosen with the expectation of
having 500 actual participants per stratum, based on participation rate estimates from the
implementer (Statistics Sweden, SCB).
Within each stratum, the investigators randomize 3 types of information sheets on the HPV
vaccine: emotionally-framed (T1), scientifically and statistically framed (T2) and
uninformative placebo (C). Along the information sheet, all mothers receive a first survey
covering their beliefs on vaccines (henceforth defined "baseline survey" for simplicity,
despite being administered along the treatment), which does not vary across treatment arms.
The information sheet and the baseline survey invitation are sent by ordinary post in June
2021 to the mother's address, and the survey can be compiled both on paper and online. In
July and August, mothers who have still not compiled the baseline survey will receive 3
reminders: each reminders contains the information sheet, which depending on the specific
reminder can be printed or accessible in digital format when accessing the online survey.
Between September and October, all mothers will have to decide whether to authorize HPV
vaccination for their child, which takes places directly at school and free of charge. In
November, mothers who have responded to the baseline survey receive an invitation to an
endline survey. All information sheets and surveys are available in Swedish, English, Arabic
and Farsi. Informed consent is obtained in the baseline survey. For mothers who choose to
participate, investigators will obtain, from population registers, background variables
concerning the mother herself, the other parent and the child who is due to immunization.
These cover specific information on parents' education, income, wealth and occupation,
marital status, number of total children, gender of the child due to HPV vaccination, and if
she/he received the previous vaccine in the national program's schedule (3 to 4 years before
our intervention), order of the child among siblings.