A decision support tool for risk-benefit analysis of Japanese encephalitis vaccine in travellers

Co-design and user testing of a Japanese encephalitis vaccine decision aid (JEVaDA)

BACKGROUND

Japanese encephalitis (JE) is a rare but potentially serious infection in travellers. While effective vaccines are available, uptake remains low. Vaccine decision aids are evidence-based tools designed to help users make informed vaccination decisions. This study details the development of a novel web-based Japanese encephalitis vaccine decision aid (JEVaDA) for travellers, following globally recognised standards.

METHODS

Collaborating with community members, healthcare providers and experts, we followed a multi-step approach, involving a scoping review, a survey of user needs, co-design workshops, user testing, and expert review. Findings from workshops and testing informed the development of decision aid prototypes, with input from a graphic designer. We used the Patient Education Materials Assessment Tool to assess understandability and actionability and the Ottawa acceptability tool to measure components of acceptability. The final version was adapted to a web-based format.

RESULTS

Five co-design workshops conducted with 16 participants (nine community members, seven healthcare providers) gathered input and feedback on the initial PDF prototype. The refined prototype was user-tested by another group of 22 participants (16 community members, six healthcare providers) and reviewed by five subject matter experts. Feedback indicated areas for improvement in risk visualisation, personalised content, and catering to diverse user needs. The decision aid scored highly for understandability (89 %) and actionability (87 %). All participants (100 %) found it suitable for decision making.

CONCLUSION

We successfully co-designed and user-tested a JE vaccine decision aid with community members, healthcare providers and experts. The interactive, web-based version is now freely available at www.monash.edu/vaccinedecisionaids-je.

Vaccines for International Travelers: Current Status and Recent Developments

Immunizations, malaria chemoprophylaxis, insect repellent use, and prevention and management of travelers' diarrhea are the cornerstones of the pretravel consultation. This report updates 1 of these topics, vaccine immunizations, for adult international travelers.

Long-term immunogenicity of a single-dose live recombinant chimeric Japanese encephalitis vaccine in adults

BACKGROUND

Japanese encephalitis virus is a leading cause of viral encephalitis in Asia, with high case-fatality rate and morbidity. Although the live recombinant Japanese encephalitis chimeric vaccine (Imojev®) offers strong initial immunity, data on long-term efficacy beyond 5 years remain limited.

METHODS

We conducted a cross-sectional study on adults vaccinated with Imojev® at a specialist travel clinic in Brisbane, Australia. Participants were stratified based on the time since vaccination: 2-5 years and >5 years. Neutralizing antibody titres were measured using the plaque reduction neutralization test (PRNT50), with titres ≥10 indicating seropositivity.

RESULTS

Of the 103 participants, 47 were vaccinated 2-5 years prior and 56 were vaccinated ≥5 years prior to enrolment. All participants vaccinated within 5 years remain seropositive, whilst 52 of 56 (92.9%) vaccinated ≥5 years ago were seropositive. Four participants (7.1%) were seronegative post-vaccination, with time since vaccination ranging from 5 to 9 years. These seronegative individuals were vaccinated a median of 9.2 years ago, compared to 5.1 years for seropositive participants (P-value = 0.037). Aside from time since vaccination, no other factors (e.g. age, sex) were associated with seronegativity.

CONCLUSIONS

Imojev® provides durable immunity, with seropositivity exceeding 90% up to 10 years post-vaccination. However, waning immunity in a small proportion of individuals suggests that booster doses may be beneficial for high-risk travellers vaccinated over 5 years ago.

Rationale for Japanese encephalitis vaccination in short-term travellers to endemic areas

Although the Japanese encephalitis (JE) vaccine is typically strongly recommended for long-term high-risk travellers, some cases of JE infections have been reported amongst short-term travellers with seemingly low risk. This article underscores the advantages and reasoning behind JE vaccination for this particular group of travellers.