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Trial registered on ANZCTR


Registration number
ACTRN12614001158651
Ethics application status
Approved
Date submitted
19/10/2014
Date registered
31/10/2014
Date last updated
30/01/2018
Type of registration
Prospectively registered

Titles & IDs
Public title
Nudges to influence influenza vaccine uptake in children: a randomised controlled trial
Scientific title
A randomised controlled trial to influence influenza vaccine uptake in children by providing key messages about influenza vaccination and timely reminders and reducing practical and financial barriers.
Secondary ID [1] 285518 0
Nil
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Influenza 293327 0
Condition category
Condition code
Public Health 293594 293594 0 0
Health promotion/education
Infection 293664 293664 0 0
Other infectious diseases

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Subjects in the intervention group will receive the publically available leaflets from the Centre for Health Protection about the 2014/15 Childhood Influenza Vaccination Subsidy Scheme (CIVSS). In addition they will receive the following interventions: (i) a concise information sheet about the risks of influenza to children and importance of vaccination for the prevention of influenza after November 2014 and again in October 2015; (ii) semi-completed forms of “Consent to Use Vaccination Subsidy” and “Parent’s Consent Form”, if required, with highlighted guidelines of where to sign and a simple reminder to take these forms and the child’s birth certificate to the clinic; (iii) the contact number and address of a specific community health centre registered under CIVSS that is in reasonable proximity to their home (United Christian Nethersole Community Health Service (UCN)). This network of clinics is able to provide the vaccine (trivalent) without any additional cost and without the need for a prior appointment. The quadrivalent influenza vaccine at UCN costs HKD20 per dose above the Government’s subsidy. We will compensate for the additional HKD20 per dose of quadrivalent influenza vaccine in terms of supermarket or book coupons at the end of the study. If neither of the UCN clinics is near the subjects’ home, a list of clinics which is in reasonable proximity to their home and provide either trivalent or quadrivalent influenza vaccine without any additional cost will be provided. This information package will be delivered following the start of 2014/2015 CIVSS and again in 2015/2016 CIVSS and each will then be followed by two telephone or text message reminders about the CIVSS. The reminders will be sent one week and 1-2 months after delivery of intervention package.
Intervention code [1] 290459 0
Behaviour
Comparator / control treatment
Subjects in the control group will receive the publically available leaflets from the Centre for Health Protection about the 2014/15 CIVSS.
Control group
Active

Outcomes
Primary outcome [1] 293405 0
Influenza vaccine uptakes by telephone interviews at 12 months and online/postal self-administrated questionnaire at 24 months.
Timepoint [1] 293405 0
At children's ages of 12 months and 24 months
Secondary outcome [1] 310952 0
Mothers' knowledge and attitudes of influenza vaccine assessed by questionnaire based on Health Belief Model.
Timepoint [1] 310952 0
At children's ages of 6 months and 24 months

Eligibility
Key inclusion criteria
Families of children who have been enrolled in a previous cohort will be invited to participate in this study. The following criteria were used for selection of the cohort participants: (i) postpartum mothers; (ii) aged older than or equal to 18 years in 2014; (iii) Cantonese speaking; (iv) have a plan to remain in Hong Kong with the infant after delivery for at least 6 months; (v) no obvious cognitive abnormality; (vi) no serious obstetrical complications and baby is full-term (37 weeks of gestation) with no congenital abnormalities; and (vii) can provide signed informed consent. A convenience sample of women who met the inclusion criteria were invited to participate.
The children eligible to participate in the study will be at 6-10 months old during recruitment.

If the recruitment rate is lower than anticipated, we will recruit additional children from postnatal wards.
Minimum age
0 Months
Maximum age
No limit
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Children will be excluded from this intervention study if they have already received influenza vaccination.

Study design
Purpose of the study
Educational / counselling / training
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
The block size used for the intervention allocation will be kept unknown to investigators and the research assistant carrying out interviews. This precaution maintains concealment. Once the intervention has been allocated, the research assistant allocating control and intervention groups will not be blinded to participants’ group assignment, but the other research assistant conducting telephone interviews, investigators and participants will be blinded to participants’ group allocation.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
After consent has been obtained, a study research assistant not involved with other follow-ups will randomly allocate all participants to either control or intervention group using block randomisation. The two groups will have similar numbers of participants. We will use R version 2.15.2 (R Development Core Team) statistical software to randomly generate the intervention allocation in random block sizes.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

The people assessing the outcomes
Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
Selection of subjects:
A previous Hong Kong study showed that the influenza vaccine uptake among children aged 6 to 23 months was 9.0%. From the literature, a study with mailed letters as intervention on healthy children aged from 6 to 23 months showed influenza vaccine uptake increased to 1 - 9.1%. With telephone or text message reminders, we expect a larger increase can be achieved. Another intervention study on children at 6 to 72 months old with chronic medical conditions achieved an approximate 20% increase after delivering a series of interventions such as mailed letters, telephone calls and contact numbers of practitioners. Thus, we estimate the influenza vaccine uptake will increase from 9% to at least 19%. Based on a required power of 80% and a significance level of 0.05, by using G*Power version 3.1.9.2, the sample size required is 330. Taking into account participants who do not wish to take part in the study or who do not complete the study (about 20% from past experience), we anticipate the 493 eligible mothers in our original PDKAP cohort that will be followed-up will provide an appropriate sample source for this study. However in a worst case scenario if recruitment is much lower than anticipated, we could still have the option of recruiting additional subjects from the wards of the main study hospital with a separate informed consent form and a baseline questionnaire. However in this case, the effect of our intervention package may have different effects on subjects recruited from these different settings (PDKAP cohort follow-up group and postnatal group). Based on the most recent seasonal influenza vaccination coverage survey done by the Department of Health in 2012/13, the coverage of seasonal influenza vaccination was 14.7% in children aged from 6 months to under 2 years. Therefore we will recruit additional children from postnatal wards with the aim to achieve sufficient sample size in the additional group i.e. 404. Even with the intention-to-treat analysis, in order to ensure the same required power (80%) and significance level (0.05), with an anticipated drop-out rate (30-35% from past experience), the sample size required for the babies of the postnatal group is 577-777. The effect of the intervention will be analysed separately for each of the two groups and then a combined analysis will be done to assess the overall effectiveness of the intervention.

Statistical analysis:
To ensure data quality, the data will be double-entered and validated using EpiData. Intention-to-treat analysis will be used with missing status of influenza vaccination taken as no vaccination. An initial univariate analysis will be performed on all variables to derive means, standard deviations and ranges. These initial results will be examined for possible errors and corrected as necessary. To assess the usefulness of the interventions, chi-squared test will be used to compare influenza vaccine uptakes between control and intervention groups. We will use multivariable regression models to assess the association between the influenza vaccination intention or uptake rate and its knowledge, attitudes and practices before and after delivering intervention materials. The two models will then be compared to assess the factors influenced by the intervention. To determine the change in knowledge, attitudes and practices after receiving intervention information, Wilcoxon signed-rank test will be performed on the paired data. All statistical analysis will be performed using statistical software R version 2.15.2 and p-value <0.05 will be taken as statistically significant.

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
11/11/2014
Actual
2/12/2014
Date of last participant enrolment
Anticipated
31/07/2015
Actual
31/07/2015
Date of last data collection
Anticipated
30/09/2017
Actual
25/09/2017
Sample size
Target
1156
Accrual to date
Final
833
Recruitment outside Australia
Country [1] 6426 0
Hong Kong
State/province [1] 6426 0

Funding & Sponsors
Funding source category [1] 290113 0
Government body
Name [1] 290113 0
Health and Medical Research Fund
Country [1] 290113 0
Hong Kong
Primary sponsor type
Individual
Name
NELSON Edmund Anthony
Address
Department of Paediatrics,
6/F, Lui Che Woo Clinical Sciences Building,
Prince of Wales Hospital,
30-32 Ngan Shing Street,
Shatin, N.T., Hong Kong,
China
Country
Hong Kong
Secondary sponsor category [1] 288820 0
None
Name [1] 288820 0
Address [1] 288820 0
Country [1] 288820 0
Other collaborator category [1] 278204 0
Individual
Name [1] 278204 0
TARRANT Marie
Address [1] 278204 0
School of Nursing,
The University of Hong Kong,
4/F, William MW Mong Block,
21 Sasson Road,
Pokfulam, Hong Kong,
China
Country [1] 278204 0
Hong Kong
Other collaborator category [2] 278205 0
Individual
Name [2] 278205 0
CHAN Ching Ching Kate
Address [2] 278205 0
Department of Paediatrics,
6/F, Lui Che Woo Clinical Sciences Building,
Prince of Wales Hospital,
30-32 Ngan Shing Street,
Shatin, N.T., Hong Kong,
China
Country [2] 278205 0
Hong Kong
Other collaborator category [3] 278435 0
Individual
Name [3] 278435 0
TAM Wing Hung
Address [3] 278435 0
Department of Obstetrics and Gynaecology, 1/F, Block EF, Prince of Wales Hospital, 30-32 Ngan Shing Street, Shatin, N.T., Hong Kong, China
Country [3] 278435 0
Hong Kong

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 291823 0
Joint Chinese University of Hong Kong - New Territories East Cluster Clinical Research Ethics Committee
Ethics committee address [1] 291823 0
Joint CUHK-NTEC Clinical Research Ethics Committee
8/F, Lui Che Woo Clinical Sciences Building,
Prince of Wales Hospital,
30-32 Ngan Shing Street,
Shatin, N.T., Hong Kong,
China
Ethics committee country [1] 291823 0
Hong Kong
Date submitted for ethics approval [1] 291823 0
15/10/2014
Approval date [1] 291823 0
10/11/2014
Ethics approval number [1] 291823 0
CRE-2014.554-T

Summary
Brief summary
Hypotheses:
The uptake of influenza vaccine provided through the Childhood Influenza Vaccination Subsidy Scheme, can be increased by providing mothers with concise information, help with completion of consent forms and other documentation necessary to utilise the CIVSS subsidy, reminders and contacts of specific CIVSS registered practitioners that do not charge fees above the HKD160 subsidy.

Primary objective:
To determine whether the intervention package can increase uptake of influenza vaccine in children aged 6 to 24 months.

Secondary objectives:
1) To increase uptake of influenza vaccine in children.
2) To provide key messages to parents about influenza vaccination.
3) To reduce practical and financial barriers that could discourage parents from participating in CIVSS.
4) To provide timely reminders to parents to encourage them to participate in CIVSS.
Trial website
Trial related presentations / publications
Public notes
Attachments [1] 612 612 0 0
/AnzctrAttachments/367280-Nudges_Protocol_20150715.pdf
Attachments [2] 613 613 0 0
/AnzctrAttachments/367280-Nudges_updated_documents_15_16.pdf
Attachments [3] 1454 1454 0 0
/AnzctrAttachments/367280-367280-Nudges_updated_documents_16_17.pdf (Supplementary information)

Contacts
Principal investigator
Name 52178 0
Prof NELSON Edmund Anthony
Address 52178 0
Department of Paediatrics,
6/F, Lui Che Woo Clinical Sciences Building,
Prince of Wales Hospital,
30-32 Ngan Shing Street,
Shatin, N.T., Hong Kong,
China
Country 52178 0
Hong Kong
Phone 52178 0
+852 26322861
Fax 52178 0
+852 26360020
Email 52178 0
[email protected]
Contact person for public queries
Name 52179 0
YEUNG Hoi Ting Karene
Address 52179 0
Department of Paediatrics,
6/F, Lui Che Woo Clinical Sciences Building,
Prince of Wales Hospital,
30-32 Ngan Shing Street,
Shatin, N.T., Hong Kong,
China
Country 52179 0
Hong Kong
Phone 52179 0
+852 26322917
Fax 52179 0
+852 26360020
Email 52179 0
[email protected]
Contact person for scientific queries
Name 52180 0
NELSON Edmund Anthony
Address 52180 0
Department of Paediatrics,
6/F, Lui Che Woo Clinical Sciences Building,
Prince of Wales Hospital,
30-32 Ngan Shing Street,
Shatin, N.T., Hong Kong,
China
Country 52180 0
Hong Kong
Phone 52180 0
+852 26322861
Fax 52180 0
+852 26360020
Email 52180 0
[email protected]

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No Supporting Document Provided



Results publications and other study-related documents

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