top of page

Health Promotion Projects on Vaccination

A randomized controlled trial evaluating efficacies of two theory-based and setting-based interventions in promoting influenza vaccination (IV) among children of 6 to 23 months old

Background: High prevalence of influenza and its complications leading to hospitalization among young children warrant interventions. Influenza vaccine (IV) can effectively reduce influenza-related complications. However, the prevalence of seasonal influenza vaccination among Hong Kong children of age 6-23 months was low.


Objectives: The primary objective was to evaluate the relative efficacies of two brief interventions versus a control in increasing the prevalence of taking up the first two shots of IV among children during the 12-month follow-up period. Secondary objectives assessed cognitions about IV. (Interventions group A:  IV-related information (booklet, recommendation leaflet signed by health professionals and celebrities) with brief health explanation and SMS reminders; Intervention Group B: Intervention A plus a 15-minute motivational interviewing (MI) session conducted over phone; Control group: Healthy eating-related information for babies and young children as control group)


Study design and methods: Parents of children aged 6 to 23 months, who had never taken up IV, were recruited when they visited the participating maternal child health centres (MCHC). With informed consent, they were randomized into one of the three treatment arms, and were anonymously and face-to-face interviewed. Further evaluations were conducted by telephone interviews at Month 3, 6, 9, and 12.  


Results: A total of 426 children (54.0% males) were recruited with 140 in Intervention group A, 143 in Intervention group B, and 143 in Control group. At Month 2, prevalence of IV was 11.9%, 12.9% and 8.1% for Groups A and B and control, respectively. Although the intervention groups showed higher prevalence than the control group, the differences were not statistically significant. The two intervention groups showed higher knowledge levels about IV than the control group but non-significant differences in cognitive measures based on the Health Belief Model, At Mont h 12, about 40% of the participants had been exposure to the message that there was a mismatch between the viral strain and the available IV vaccines and over 40% acknowledged that the news had reduced their intention to have their young children vaccinated.


Conclusions:  The results suggested that a brief intervention conducted at MCHC setting was unable to increase IV vaccination by a large extent; the small difference might be due to a low dosage effect. The result was however subjected to an alternate explanation that the news about the mismatch might have suppressed the intention to have young children vaccinated. The study therefore may have good internal validity but diminished external validity. The MI part was also non-significant. The literature showed that MI was effective in many but not all cases. This part was also subjected to the external event of the mismatch.


The current study contributed to the evidence-base of evaluating the MI approach, even it did not provide evidence to support the advantage of using IV-related information plus MI over the two other approaches. Considering the inevitable influence of mismatch of influenza vaccine in 2014-2015 season, the similar promotion is recommended to implement in general circumstance to further test its efficacy in IV uptake and related perceptions.   

Funded by Health and Medical Research Fund


bottom of page