Fuk-Yuen Yu

Background/Objectives: Seasonal influenza vaccination (SIV) coverage remains suboptimal among adults aged ≥50 years, and the COVID-19 pandemic might influence the determinants of SIV uptake. This systematic review aimed to identify determinants of SIV uptake among adults aged ≥50 years during and after the COVID-19 pandemic. Methods: We searched PubMed, MEDLINE, Embase, Web of Science, Global Health, CINAHL, Cochrane Library, APA PsycINFO, and APA PsycArticles for studies published between 1 December 2019 and 1 January 2026. The pooled prevalence of SIV uptake was synthesized using random-effects models in meta-analysis. Results: A total of 50 studies were included in the systematic review. COVID-19-related factors, such as perceived risk of co-infection with SARS-CoV-2 and seasonal influenza and concerns about potential interactions between COVID-19 vaccines and SIV, were determinants of SIV uptake. Other modifiable determinants included those that existed before the pandemic (e.g., knowledge and perceptions of seasonal influenza and SIV). Subgroup analysis showed that cost and inaccessibility were barriers to receiving SIV in places without a fully subsidized SIV, and perceived susceptibility and vaccine safety concerns were commonly identified as facilitators and barriers in studies with data collected after the pandemic. The pooled prevalence of SIV uptake among adults aged 50 years or above was 53% (95% confidence interval: 44–62%). Such uptake appeared lower among adults aged 50–64 years, in regions without a fully subsidized SIV, and after the COVID-19 pandemic. Conclusions: These findings could inform service planning and interventions promoting SIV uptake among adults aged ≥50 years in the post-pandemic era. More studies are needed to explore determinants specific to people aged 50–64 years to inform health promotion tailored to their needs.

BACKGROUND Sexualized drug use (SDU)—the use of recreational substances before or during sex—is increasingly prevalent among gay, bisexual, and other men who have sex with men (GBMSM) and is linked to HIV, hepatitis C, sexually transmitted infections (STIs), and mental health and substance-related harms. Existing interventions to prevent SDU are limited. Interventions tailored to one’s current stage of change (SOC) are effective in reducing substance use. A hybrid chatbot was developed for this study. The rule-based component ensures that carefully co-designed SOC-tailored interventions are delivered as intended. The AI component will use natural language processing (NLP) to support real-time question-and-answer (Q&A) functions. OBJECTIVE This randomized controlled trial (RCT) will evaluate whether accessing the hybrid chatbot on top of web-based educational videos is more effective than watching web-based videos alone in reducing SDU in the past 3 months among GBMSM in Hong Kong. METHODS This is a partially blinded (outcome assessors and data analysts) and parallel-group RCT. A total of 100 Cantonese-speaking GBMSM aged 18 years or older in Hong Kong will be randomized evenly into either the intervention group or the control group. In the control group, participants will receive links via WhatsApp to access 12 weekly web-based educational videos. In addition to the web-based videos watched by the control group, those in the intervention group will have access to the hybrid chatbot during the 12-week intervention period. The rule-based component of the chatbot will first assess participants’ SOC regarding sexualized drug use and then deliver co-designed SOC-tailored interventions across 12 weekly sessions. The Q&A component, supported by a co-created Q&A database and natural language processing (NLP) functions, will allow users to raise questions and receive real-time responses. Participants will be interviewed at baseline (T0), after completion of the intervention period (T1), and 3 months after T1 (T2). The primary outcome is the presence of SDU in the past 3 months. Secondary outcomes include SOC related to SDU, condomless anal intercourse in the past 3 months, HIV and other sexually transmitted infection (STI) testing uptake in the past 3 months, use of pre-exposure prophylaxis (PrEP) and depressive and anxiety symptoms. Intention-to-treat analyses use generalized estimating equations and mixed-effects models, with sensitivity analyses for missing data. RESULTS : Recruitment commenced in February 2026. By June 2026, 102 participants had been enrolled and completed baseline assessments; of these, 51 (50%) were randomized to the intervention group and 51 (50%) to the control group. The follow-up assessment at T1 started in June 2026. Data collection is expected to be completed in January 2027. CONCLUSIONS The findings will contribute to the evidence of the effectiveness of SOC-tailored and chatbot-delivered interventions. If the hybrid chatbot is proven effective, it can be integrated within existing community and non-governmental infrastructure and adapted for other Chinese-speaking GBMSM populations. CLINICALTRIAL ClinicalTrials.gov NCT07472582; https://clinicaltrials.gov/study/NCT07472582

Background: Self-compassion is the practice of treating oneself with kindness and understanding during times of hardship. There is a lack of studies investigating the associations between self-compassion and vaccination behaviors. This study investigated the associations between self-compassion and behavioral intention to receive seasonal influenza vaccination (SIV), pneumococcal vaccination (PV), and respiratory syncytial virus (RSV) vaccination among community-living older adults in Western China. Methods: A cross-sectional survey was conducted among people aged ≥60 years in Kashgar, China between January and February 2026. Participants were recruited through multi-stage random sampling. Multivariable logistic regression models were fitted. Results: Among all participants, 56.5% intended to receive a fully subsidized SIV in the next year. Among those without a prior vaccination history, 48.2% and 49.7% intended to receive fully subsidized PV and RSV vaccination in the next year, respectively. After adjusting for significant background characteristics, higher levels of self-compassion (e.g., higher levels of mindfulness, self-kindness and common humanity, and lower levels of over-identification, isolation and self-judgment) were associated with higher odds of behavioral intention to receive a fully subsidized SIV, PV and/or RSV vaccination. Conclusions: Our findings suggested a new angle to promote vaccination uptake. Future studies may evaluate the efficacy of self-compassion interventions in improving vaccination uptake among older adults.

Background: Mpox perceptions may influence the onset of sexual behaviors (e.g., condomless anal sex [CAS] with men, number of male sex partners, and sexualized drug use) among gay, bisexual, and other men who have sex with men (GBMSM). However, no studies have examined how mpox illness representations relate to sexual behaviors. This study examined the associations between mpox illness representations and presence of sexual behaviors among GBMSM in Beijing and Hong Kong. Methods: This secondary analysis of a cross-sectional survey conducted between November 2023 and March 2024 among GBMSM in Beijing and Hong Kong. Eligible participants were Chinese males aged ≥ 18 years who had anal sex with at least one man in the past six months. Participants were recruited through venue-based outreach, online platforms, and peer referrals, and completed a structured telephone interview. Multivariable logistic and negative binomial regression models assessed the associations between mpox illness representations and sexual behaviors. Results: A total of 524 GBMSM in Beijing and 613 in Hong Kong participated (response rates: 87% and 86%). After adjustment, GBMSM in Beijing perceived more severe consequences, longer expected illness timeline, greater personal control, more concern, and better understanding related to mpox than their counterparts in Hong Kong. In Beijing, better understanding of mpox (coherence) was associated with lower odds of CAS with men (adjusted odds ratio = 0.92, 95% CI: 0.87–0.98), while longer expected illness timeline (timeline) (incidence rate ratio [IRR] = 0.96, 95% CI: 0.93–1.00), anticipating more severe symptoms if infected (identity) (IRR = 0.94, 95% CI: 0.90–0.97) and stronger negative emotions (emotion) (IRR = 0.94, 95% CI: 0.90–0.98) were associated with fewer male sex partners. In contrast, greater personal control (IRR = 1.06, 95% CI: 1.02–1.10) was associated with higher number of male sex partners in Beijing. Conclusions: Associations between mpox-related illness perceptions and sexual behaviors were observed between GBMSM in Beijing but were not detected in Hong Kong. Future studies may explore whether modifying mpox-related illness representation is helpful to promote safe sexual behaviors among GBMSM in Beijing. Trial registration: Not applicable.

Background: Older adults are more vulnerable to severe consequences caused by seasonal influenza. Although seasonal influenza vaccination (SIV) is effective and free vaccines are available, the SIV uptake rate remained inadequate among people aged 65 years or older in Hong Kong, China. There was a lack of studies evaluating ChatGPT in promoting vaccination uptake among older adults. Objective: This study aimed to evaluate the effectiveness of ChatGPT with retrieval-augmented generation in increasing SIV uptake among older adults over a 3-month study period in Hong Kong, China. Participants in an ongoing observational cohort study conducted in the same period served as the comparison group. Methods: A quasi-experimental study was conducted between November 2024 and April 2025. Participants were (1) aged ≥65 years, (2) possessed a Hong Kong ID, (3) able to speak and comprehend Cantonese, (4) smartphone users, and (5) had no SIV uptake for the approaching flu season. Those with a diagnosis of cognitive impairment or dementia, blindness or deafness, or known contraindications to the SIV were excluded. Participants were recruited through random telephone calls. There were 45 and 55 participants in the SIV-ChatGPT group and the comparison group, respectively. All participants completed follow-up surveys at T1 (1 month after the baseline survey, for the SIV-ChatGPT group only) and T2 (3 months after the baseline survey, for both groups). Participants in the SIV-ChatGPT group gained access to SIV-ChatGPT in the format of a web-based app after completion of the baseline survey. They could use SIV-ChatGPT repeatedly throughout a 1-month intervention period and were free to spend as much time as they wanted with SIV-ChatGPT. Intention-to-treat analysis was used for outcome analyses. Results: At T2, the SIV uptake rate was higher in the SIV-ChatGPT group than the comparison group (15/45, 33% vs 8/55, 14.3%; adjusted odds ratio 2.72, 95% CI 1.01-7.35, P=.048). All participants were able to provide receipts to validate their SIV uptake. In the SIV-ChatGPT group, 40.5% (15/37) of participants who used SIV-ChatGPT at least once reported a SIV uptake at T2, which was significantly higher than nonusers (0/8, 0%; P=.04). Among the 37 SIV-ChatGPT users, the mean score of the System Usability Scale was 67.1 (SD 14.9). Levels of subjective behavioral and cognitive engagement with SIV-ChatGPT were relatively high, while the affective engagement was moderate. Conclusions: SIV-ChatGPT was feasible and acceptable and demonstrated preliminary effectiveness in increasing SIV uptake among people aged 65 years or older. This study also provided implications to improve the performance of SIV-ChatGPT. A full-powered randomized controlled trial should be considered to evaluate its efficacy. Trial Registration: ClinicalTrials.gov NCT06679647; https://clinicaltrials.gov/study/NCT06679647

Background: Physical activity (PA) has significant health benefits for older adults. However, many older adults in Hong Kong remain physically inactive. Interventions tailored to one’s current stage of change (SOC) are more effective than non-SOC-tailored ones in facilitating behavioral changes. Chatbots are potentially useful to deliver SOC-tailored interventions to promote PA among older adults. Objective: This randomized controlled trial (RCT) will compare the efficacy of an SOC- versus a non-SOC-tailored intervention in increasing the prevalence of meeting World Health Organization (WHO)-recommended PA levels 6 months after completion of the intervention among inactive community-dwelling individuals aged ≥65 years. Methods: This is a partially blinded (outcome assessors and data analysts) and parallel-group RCT. A total of 278 inactive community-dwelling people aged 65 years or more will be randomized evenly into either an intervention group or a control group. In the intervention group, a fully automated chatbot with natural language processing (NLP) functions will measure participants’ SOC related to PA and deliver web-based interventions tailored to their current SOC every week for 12 weeks. In the control group, the chatbot will not measure participants’ SOC but will deliver a non-SOC-tailored web-based intervention every week for 12 weeks. Participants will be interviewed at baseline (T0), after completion of the intervention (T1), and 6 months after T1 (T2). The primary outcome is the prevalence of meeting WHO-recommended PA levels (ie, at least 150 minutes of moderate-intensity aerobic PA, at least 75 minutes of vigorous-intensity aerobic PA, or an equivalent combination of moderate-to-vigorous physical activity [MVPA] every week). PA will be measured using the Chinese version of the International Physical Activity Questionnaire Short Form (IPAQ-SF) and accelerometers at T0, T1, and T2. Secondary outcomes include (1) minutes of MPVA, low-intensity PA, and sedentary time in the past week; (2) step counts in the past week; (3) SOC levels, perceived pros, perceived cons, and perceived self-efficacy related to PA; (4) compliance to the web-based interventions; and (5) cognitive status measured at T0, T1, and T2. Intention-to-treat analysis will be used for data analysis. Results: Recruitment started in November 2024. By February 2025, a total of 185 participants completed the baseline assessment and were randomly assigned to either the intervention group (n=93, 50.3%) or the control group (n=92, 49.7%). Recruitment will be completed by the end of June 2025. The follow-up assessment at T1 started in March 2025. Data collection is expected to be concluded in February 2026. Conclusions: The findings will extend the application of SOC and contribute to the evidence of the effectiveness of SOC-tailored and chatbot-delivered interventions. If the chatbot-delivered SOC-tailored intervention is proven effective to increase PA levels, it will require relative less resources to implement and maintain. It can be integrated into the existing WhatsApp groups operated by organizations providing services to older adults in Hong Kong and create public health impacts. Trial Registration: ClinicalTrial.gov: NCT06641492; https://clinicaltrials.gov/study/NCT06641492 International Registered Report Identifier (IRRID): DERR1-10.2196/68796

Background: Exposure to information about mpox may shape distinct perceptual processes that influence vaccination intent. Understanding how such information impacts perceived risk and vaccination intention is crucial for designing effective risk communication and public health messaging, particularly among populations at high risk such as gay, bisexual, and other men who have sex with men (GBMSM). Objective: This study examined the specific pathways through which mpox information exposure and associated perceptual processes influence vaccination intent. Differences between GBMSM in Beijing and Hong Kong were also examined to explore potential contextual influences. Methods: We conducted a cross-sectional survey of mpox-unvaccinated GBMSM in Hong Kong (n=470) and Beijing (n=519) between November 2023 and March 2024. Structural equation modeling was conducted to estimate the direct and indirect effects of information exposure, perceptual processes (eg, perceived control and threat perceptions), and perceived risk on vaccination intent. Multigroup structural equation modeling was used to estimate the effect measure modification by city. Results: Exposure to positive mpox information significantly enhanced perceived control (β=0.33; P=.001) and increased vaccination intention through heightened perceived risk of contracting mpox (β=0.27; P<.001) in the following 6 months. The indirect effect of positive information exposure on vaccination intent via perceived control and risk was significant in Hong Kong (B=0.01; Wald test: Z=3.05 and P=.002) but not in Beijing (B=−0.01; P=.25). Conversely, negative information exposure primarily increased threat perceptions (Hong Kong: B=0.33 and P=.001; Beijing: B=0.93 and P<.001) but did not consistently translate to increased perceived risk of contracting mpox (Hong Kong: B=−0.10 and P=.31; Beijing: B=0.20 and P=.11). Notable contextual differences emerged between Beijing and Hong Kong—participants in Beijing reported higher levels of information exposure (eg, international mpox statistics; mean score 2.17, SD 0.97 vs 1.79, SD 0.89; P<.001) and more nonregular sex partners (mean 2.20, SD 6.73 vs 1.65, SD 3.37; P=.02), but the associations among information exposure, perceived risk, and vaccination intent were weaker than in Hong Kong participants. Conclusions: Positive mpox-related information strongly promotes vaccination intent by enhancing perceived control and amplifying perceived risk, particularly in settings with accessible vaccination programs such as Hong Kong. Conversely, negative information appears less effective in driving vaccination intention. Tailored, stigma-free communication is crucial for improving vaccination uptake, especially in mainland China, where subsidized vaccines are scarce and perceptual pathways linking information exposure to vaccination intent are relatively weak. Enhancing access to vaccines and addressing contextual barriers can further optimize the impact of such interventions.

BACKGROUND Older adults are more vulnerable to severe consequences caused by seasonal influenza. Although seasonal influenza vaccination (SIV) is effective and free vaccines are available, the SIV uptake rate remained inadequate among people aged 65 years or older in Hong Kong, China. There was a lack of studies evaluating ChatGPT in promoting vaccination uptake among older adults. OBJECTIVE This study aimed to evaluate the effectiveness of ChatGPT with retrieval-augmented generation in increasing SIV uptake among older adults over a 3-month study period in Hong Kong, China. Participants in an ongoing observational cohort study conducted in the same period served as the comparison group. METHODS A quasi-experimental study was conducted between November 2024 and April 2025. Participants were (1) aged ≥65 years, (2) possessed a Hong Kong ID, (3) able to speak and comprehend Cantonese, (4) smartphone users, and (5) had no SIV uptake for the approaching flu season. Those with a diagnosis of cognitive impairment or dementia, blindness or deafness, or known contraindications to the SIV were excluded. Participants were recruited through random telephone calls. There were 45 and 55 participants in the SIV-ChatGPT group and the comparison group, respectively. All participants completed follow-up surveys at T1 (1 month after the baseline survey, for the SIV-ChatGPT group only) and T2 (3 months after the baseline survey, for both groups). Participants in the SIV-ChatGPT group gained access to SIV-ChatGPT in the format of a web-based app after completion of the baseline survey. They could use SIV-ChatGPT repeatedly throughout a 1-month intervention period and were free to spend as much time as they wanted with SIV-ChatGPT. Intention-to-treat analysis was used for outcome analyses. RESULTS At T2, the SIV uptake rate was higher in the SIV-ChatGPT group than the comparison group (15/45, 33% vs 8/55, 14.3%; adjusted odds ratio 2.72, 95% CI 1.01-7.35, P=.048). All participants were able to provide receipts to validate their SIV uptake. In the SIV-ChatGPT group, 40.5% (15/37) of participants who used SIV-ChatGPT at least once reported a SIV uptake at T2, which was significantly higher than nonusers (0/8, 0%; P=.04). Among the 37 SIV-ChatGPT users, the mean score of the System Usability Scale was 67.1 (SD 14.9). Levels of subjective behavioral and cognitive engagement with SIV-ChatGPT were relatively high, while the affective engagement was moderate. CONCLUSIONS SIV-ChatGPT was feasible and acceptable and demonstrated preliminary effectiveness in increasing SIV uptake among people aged 65 years or older. This study also provided implications to improve the performance of SIV-ChatGPT. A full-powered randomized controlled trial should be considered to evaluate its efficacy. CLINICALTRIAL ClinicalTrials.gov NCT06679647; https://clinicaltrials.gov/study/NCT06679647

BACKGROUND Exposure to information about mpox may shape distinct perceptual processes that influence vaccination intent. Understanding how such information impacts perceived risk and vaccination intention is crucial for designing effective risk communication and public health messaging, particularly among populations at high risk such as gay, bisexual, and other men who have sex with men (GBMSM). OBJECTIVE This study examined the specific pathways through which mpox information exposure and associated perceptual processes influence vaccination intent. Differences between GBMSM in Beijing and Hong Kong were also examined to explore potential contextual influences. METHODS We conducted a cross-sectional survey of mpox-unvaccinated GBMSM in Hong Kong (n=470) and Beijing (n=519) between November 2023 and March 2024. Structural equation modeling was conducted to estimate the direct and indirect effects of information exposure, perceptual processes (eg, perceived control and threat perceptions), and perceived risk on vaccination intent. Multigroup structural equation modeling was used to estimate the effect measure modification by city. RESULTS Exposure to positive mpox information significantly enhanced perceived control (β=0.33; P=.001) and increased vaccination intention through heightened perceived risk of contracting mpox (β=0.27; P<.001) in the following 6 months. The indirect effect of positive information exposure on vaccination intent via perceived control and risk was significant in Hong Kong (B=0.01; Wald test: Z=3.05 and P=.002) but not in Beijing (B=−0.01; P=.25). Conversely, negative information exposure primarily increased threat perceptions (Hong Kong: B=0.33 and P=.001; Beijing: B=0.93 and P<.001) but did not consistently translate to increased perceived risk of contracting mpox (Hong Kong: B=−0.10 and P=.31; Beijing: B=0.20 and P=.11). Notable contextual differences emerged between Beijing and Hong Kong—participants in Beijing reported higher levels of information exposure (eg, international mpox statistics; mean score 2.17, SD 0.97 vs 1.79, SD 0.89; P<.001) and more nonregular sex partners (mean 2.20, SD 6.73 vs 1.65, SD 3.37; P=.02), but the associations among information exposure, perceived risk, and vaccination intent were weaker than in Hong Kong participants. CONCLUSIONS Positive mpox-related information strongly promotes vaccination intent by enhancing perceived control and amplifying perceived risk, particularly in settings with accessible vaccination programs such as Hong Kong. Conversely, negative information appears less effective in driving vaccination intention. Tailored, stigma-free communication is crucial for improving vaccination uptake, especially in mainland China, where subsidized vaccines are scarce and perceptual pathways linking information exposure to vaccination intent are relatively weak. Enhancing access to vaccines and addressing contextual barriers can further optimize the impact of such interventions.

BACKGROUND Physical activity (PA) has significant health benefits for older adults. However, many older adults in Hong Kong remain physically inactive. Interventions tailored to one’s current stage of change (SOC) are more effective than non-SOC-tailored ones in facilitating behavioral changes. Chatbots are potentially useful to deliver SOC-tailored interventions to promote PA among older adults. OBJECTIVE This randomized controlled trial (RCT) will compare the efficacy of an SOC- versus a non-SOC-tailored intervention in increasing the prevalence of meeting World Health Organization (WHO)-recommended PA levels 6 months after completion of the intervention among inactive community-dwelling individuals aged ≥65 years. METHODS This is a partially blinded (outcome assessors and data analysts) and parallel-group RCT. A total of 278 inactive community-dwelling people aged 65 years or more will be randomized evenly into either an intervention group or a control group. In the intervention group, a fully automated chatbot with natural language processing (NLP) functions will measure participants’ SOC related to PA and deliver web-based interventions tailored to their current SOC every week for 12 weeks. In the control group, the chatbot will not measure participants’ SOC but will deliver a non-SOC-tailored web-based intervention every week for 12 weeks. Participants will be interviewed at baseline (T0), after completion of the intervention (T1), and 6 months after T1 (T2). The primary outcome is the prevalence of meeting WHO-recommended PA levels (ie, at least 150 minutes of moderate-intensity aerobic PA, at least 75 minutes of vigorous-intensity aerobic PA, or an equivalent combination of moderate-to-vigorous physical activity [MVPA] every week). PA will be measured using the Chinese version of the International Physical Activity Questionnaire Short Form (IPAQ-SF) and accelerometers at T0, T1, and T2. Secondary outcomes include (1) minutes of MPVA, low-intensity PA, and sedentary time in the past week; (2) step counts in the past week; (3) SOC levels, perceived pros, perceived cons, and perceived self-efficacy related to PA; (4) compliance to the web-based interventions; and (5) cognitive status measured at T0, T1, and T2. Intention-to-treat analysis will be used for data analysis. RESULTS Recruitment started in November 2024. By February 2025, a total of 185 participants completed the baseline assessment and were randomly assigned to either the intervention group (n=93, 50.3%) or the control group (n=92, 49.7%). Recruitment will be completed by the end of June 2025. The follow-up assessment at T1 started in March 2025. Data collection is expected to be concluded in February 2026. CONCLUSIONS The findings will extend the application of SOC and contribute to the evidence of the effectiveness of SOC-tailored and chatbot-delivered interventions. If the chatbot-delivered SOC-tailored intervention is proven effective to increase PA levels, it will require relative less resources to implement and maintain. It can be integrated into the existing WhatsApp groups operated by organizations providing services to older adults in Hong Kong and create public health impacts. CLINICALTRIAL ClinicalTrial.gov: NCT06641492; https://clinicaltrials.gov/study/NCT06641492 INTERNATIONAL REGISTERED REPORT DERR1-10.2196/68796