Dynamicity of HIV Pre-exposure Prophylaxis Usage Pattern and Association with Executed Adherence in MSM: An Implementation Study in Hong Kong.

Pre-exposure prophylaxis (PrEP) use has been shown to be effective for HIV prevention in men who have sex with men (MSM). PrEP use coverage aside, maintenance of high PrEP adherence is crucial in ensuring the achievement of HIV prevention. In this PrEP implementation study in Hong Kong, we examined the patterns of PrEP use in MSM and evaluated their association with prevention-effective adherence for HIV prevention. In January 2020-June 2021 in Hong Kong, 312 recruited MSM (median 30 years old) were followed up for 1 year, with HIV and creatinine testing, consultation, and PrEP refill. No HIV breakthrough infection was observed. As a measure of prevention-effective adherence, executed adherence (EA) was expressed as the proportion of days with HIV risk that were protected by PrEP and/or condom in 6 months. In 65,585 diary entries of 215 MSM, the median proportion of EA achieved was 89% (IQR 84-93%). Three latent classes of PrEP users were identified by latent class analysis. Taking Class 1 "daily dominant PrEP" (n = 113, 53%) as reference, Class 2 "episodic PrEP" (n = 76, 35%) was adopted by MSM with less sexual activity, had less PrEP refill and lower EA level, while Class 3 "mixed PrEP schedule" (n = 26, 12%) MSM were more sexually active but with a similar EA level. The study findings showed varied and dynamic PrEP usage patterns in the real-world setting. Strategies for promoting adherence are needed to ensure the maintenance of high EA level among PrEP-using MSM especially those on episodic PrEP schedule.

Self-sampled multi-anatomic site testing for uncovering the community burden of undiagnosed Chlamydia trachomatis and Neisseria gonorrhoeae infection in men who have sex with men.

PURPOSE: To detect otherwise undiagnosed asymptomatic sexually transmitted infection (STI), and for estimating prevalence among men who have sex with men (MSM). METHODS: In this community-based study in Hong Kong, adult MSM were recruited. After completion of an online survey, free multi-anatomic sites self-sampling kits (urine specimens, pharyngeal and rectal swabs) for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) tests were delivered to requesting participants. Factors associated with STI positivity were analyzed in logistic regression. RESULTS: From September 2021 to October 2022, 712 MSM were recruited, with 86% aged 18-39, and 16% reported history of chemsex engagement. A majority (81%) had previously undergone HIV testing, 68% had ever tested for STI, and 35% previously diagnosed with STI. Totally 428 (60%) had requested self-sampling kits, and 276 (39%) returned collected samples. Among participants who returned the samples, about half had never been tested in the past and had no history of STI. Overall 21% tested positive for CT and/or NG (CT/NG)-CT positive 16% and NG positive 7%. By anatomic site, 16% of rectal swabs, 7% of pharyngeal swabs, but just 3% of urine specimens were CT/NG positive. The prevalence of CT/NG was not significantly different by history of STI diagnosis and testing. CONCLUSION: Self-sampled STI testing is a potentially useful means for enhancing uptake of screening in MSM in the community, which could uncover otherwise undiagnosed asymptomatic infections. Internet-based self-sampling for STI testing could complement the current clinic-based STI testing for supporting epidemiologic evaluation of STI control in the community.

Temporal Changes in Sexually Transmitted Infections in a Cohort of Men Who Have Sex with Men Living with HIV: Sex Partner Seeking and Behavioral Correlates.

With "undetectable equals untransmittable," continued engagement in condomless sex has prolonged STI risk in people living with HIV. This study examined the pattern and relationship between STI diagnosis and sex partner-seeking practice over time in a cohort of men who have sex with men (MSM) attending the HIV specialist clinic in Hong Kong. Participants' STI diagnosis record since HIV diagnosis was retrieved and their frequency of seeking sex partners (A) before, (B) after HIV diagnosis, and (C) following extended period (5-10 years), through eight different settings, was assessed in two rounds of survey, along with their risk behavioral profile. Multivariable regression models were employed to study the factors associated with STI diagnosis and partner-seeking frequency, while their temporal relationships over the three time points (A-C) were examined using cross-lagged panel model. Of 345 subjects recruited, STI incidence dropped from 252 to 187 cases/1000 person-years during 2015-2019. Totally 139/212 MSM (66%) had ≥ 1 episode of STI within the 10-year period after HIV diagnosis, giving an 11-20% annual prevalence. The reduced frequency of seeking sex partner was well preserved following diagnosis with a rebound specifically noted in the use of mobile application, the patrons of which were more likely to be co-infected with STI in 2019. Chemsex, concurrent partnership, and casual sex were risk factors shared between frequent partner-seeking practice and STI diagnosis. A robust autoregressive effect for partner-seeking frequency was also identified, and which significantly predicted STI risk in the long term. To enhance HIV care, the co-administration of STI/behavioral surveillance should be emphasized.

Implementation Cascade of a Social Network-Based HIV Self-testing Approach for Men Who Have Sex With Men: Cross-sectional Study.

BACKGROUND: HIV testing is the cornerstone of strategies for achieving the fast-track target to end the AIDS epidemic by 2030. Self-testing has been proven to be an effective health intervention for men who have sex with men (MSM). While social network-based approaches for distributing HIV self-tests are recommended by the World Health Organization, their implementation consists of multiple steps that need to be properly evaluated. OBJECTIVE: This study aimed to assess the implementation cascade of a social network-based HIV self-test approach for reaching MSM who had never undergone testing in Hong Kong. METHODS: This is a cross-sectional study. Seed MSM participants were recruited through different web-based channels, who in turn invited their peers to participate in this study. A web-based platform was set up to support the recruitment and referral process. Participants could request for an oral fluid or a finger-prick HIV self-test, with or without real-time support, after completing a self-administered questionnaire. Referrals could be made upon uploading the test result and passing the web-based training. Characteristics of participants completing each of these steps and their preferences for the type of HIV self-test were evaluated. RESULTS: A total of 463 MSM were recruited, including 150 seeds. Participants recruited by seeds were less likely to have previously been tested for HIV (odds ratio [OR] 1.80, 95% CI 1.06-3.04, P=.03) and have lower confidence in performing self-tests (OR 0.66, 95% CI 0.45-0.99, P=.045). Almost all (434/442, 98%) MSM who completed the questionnaire requested a self-test, of whom 82% (354/434) had uploaded their test results. Participants requesting support were new to self-testing (OR 3.65, 95% CI 2.10-6.35, P<.001) and less confident in carrying out the self-test correctly (OR 0.35, 95% CI 0.22-0.56, P<.001). More than half (216/354, 61%) of the eligible participants initiated the referral process by attempting the web-based training with a passing rate of 93% (200/216). They were more likely to have sought sex partners (OR 2.20, 95% CI 1.14-4.25, P=.02), especially through location-based networking apps (OR 2.13, 95% CI 1.31-3.49, P=.002). They also gave higher usability scores along the implementation cascade (median 81 vs 75, P=.003). CONCLUSIONS: The social network approach was effective in diffusing HIV self-tests in the MSM community and reaching nontesters. Support and option to choose a preferable type of self-test are essential to address users' individual needs when delivering HIV self-tests. A positive user experience throughout the processes along the implementation cascade is vital to transform a tester into a promoter. TRIAL REGISTRATION: ClinicalTrials.gov NCT04379206; https://clinicaltrials.gov/ct2/show/NCT04379206.

Shifts of SARS-CoV-2 exposure settings in the transmission clusters of 2 epidemic waves in Hong Kong.

Exposure setting is crucial in the formation and propagation of SARS-CoV-2 transmission clusters. In this cohort study, transmission networks of 2 waves were differentiated by exposure setting using territory-wide surveillance data with clinical and laboratory records in Hong Kong. Characteristically, the first wave had resulted from imported cases followed by local transmissions, while the second wave was constituted primarily by local infections. With a 4-fold higher caseload, the second wave featured predominance of epidemiologically linked, local, older and asymptomatic patients with higher viral loads and shorter inpatient days. The 1028 transmission clusters formed 155 cascades composing at least two clusters. Daily and social activities were exposure settings that bridged clusters while residences usually terminated transmission cascades. Regulatory restrictions on social activities extinguished cluster formation in bars, but shifted to private parties in the second wave. The results confirmed that strategic interventions targeting exposure settings could achieve effective epidemic control.

Awareness of HIV functional cure and willingness in participating in related clinical trials: comparison between antiretroviral naïve and experienced men who have sex with men living with HIV.

BACKGROUND: Human immunodeficiency virus (HIV) functional cure is a novel biomedical strategy characterized by sustained viral suppression without the need for life-long medications. The attitude of people living with HIV (PLHIV) towards functional cure and clinical trials are understudied. We aimed to examine the awareness and levels of anticipation for HIV functional cure among men who have sex with men (MSM) living with HIV, and their willingness to join trials as differentiated by their antiretroviral treatment status. METHODS: MSM living with HIV with and those without treatment history were recruited from Hong Kong's HIV specialist clinics. Self-administered questionnaires covering behavioral profile, perceived impact of HIV cure, attitude towards HIV functional cure and related clinical trials were collected. Clinical data were separately transcribed. Determinants of perceptions and attitudes were identified by logistic regression models. RESULTS: Of 356 MSM living with HIV recruited, less than half (42%) were aware of HIV functional cure, but they had a high level of anticipation for it. Treatment-experienced participants were more likely to be aware of HIV functional cure. Awareness was associated with continued engagement in sexual activities after HIV diagnosis and sexually transmitted infection (STI) diagnosis. Higher anticipation was observed among older MSM living with HIV but it was negatively associated with one's awareness. Over 90% were willing to join functional cure trials, especially those who had previously been diagnosed with STI and had engaged in chemsex in the past year. Advice from healthcare professional was an important factor considered by those willing to join clinical trials. Younger, better educated MSM, and those with lower CD4 counts were more concerned about potential risk of AIDS and potential complications upon trial participation. CONCLUSIONS: MSM living with HIV, especially those sexually active, showed positive attitude towards functional cure and willingness to join related clinical trials despite low awareness. To enhance preparedness for HIV functional cure trials, community education, updated information and appropriate medical advice would be needed. Safety is a major concern for potential enrollees in HIV functional cure trials.

Predictors of HIV Testing and Their Influence on PrEP Acceptance in Men Who Have Sex with Men: A Cross-Sectional Study.

HIV testing is the gateway to biomedical means of prevention and treatment. Identifying predictors of HIV testing is important to inform future preventive interventions. Of 444 men who have sex with men without known HIV infection enrolled in a study in Hong Kong, 64% had ever been HIV-tested. Testers were generally older, better educated, had a higher monthly income, and more likely self-identified as gay. Testers often used Internet and frequented saunas for sex networking, compared with non-testers attending bars, massage centres and public toilets. HIV testing habit also varied with the profile of body image type and preferred type in sex networking. Higher acceptance of pre-exposure prophylaxis (PrEP) was observed among testers. Overall, socioeconomic status played an important role in both HIV testing and access to PrEP. Interventions targeting sex networking venues and alternative means of testing provision are needed to increase coverage of HIV testing.

Participation dynamics of a cohort of drug users in a low-threshold methadone treatment programme.

BACKGROUND: The low-threshold methadone maintenance treatment (MMT) programme in Hong Kong has been in place for about 40 years. Assessment of the participation pattern of methadone users may inform future programme development to achieve effective harm reduction. METHODS: Longitudinal clinical data of methadone users who first registered for MMT in the year 2008 in Hong Kong were retrieved after ethical and institutional approval. Participation pattern of this cohort was evaluated by examining users' frequency of attendance and then the overall retention rate. A subgroup of consistent users who remained on treatment in 2012 and/or 2013 was analysed. Comparison was made between high- and low-frequency users, and among high/moderate and low consistency users, to test their correlations with socio-demographics and social connectivity. RESULTS: The cohort of methadone users registering in the year 2008 was composed of 351 persons, 77 % of whom were ethnic Chinese, with a median age of 34 and the duration of heroin dependency of 6 years. The participation pattern of methadone users was highly variable, with a 6-year retention rate of 38 %. Discontinuations or 'breaks' of >28 days had occurred in 212 (60 %) methadone users. About one third (n = 117) were high-frequency users who had attended more than twice a week for at least 90 % of their treatment periods. The dosages received by high-frequency users were generally higher. Of those continuing on treatment in the fifth and/or sixth year (n = 185), 30 (16 %), 29 (16 %) and 126 (68 %) gave a high, moderate and low level of consistency as defined by the lengths of breaks. High/moderate consistency users had a longer history of heroin use and a higher degree of connectivity with other users by social network analysis. CONCLUSIONS: Despite the variability of frequency and consistency of attendance of drug users enrolling in the low-threshold MMT programme in Hong Kong, a consistent pattern could be seen in the proportional distribution of dosage and participation efforts. Whereas an adequate dosage was a potential predictor of optimal frequency of attendance, demographics and connectivity had varied between continued users with different levels of consistency.

Population Behavior Changes Underlying Phasic Shifts of SARS-CoV-2 Exposure Settings Across 3 Omicron Epidemic Waves in Hong Kong: Prospective Cohort Study.

BACKGROUND: Exposure risk was shown to have affected individual susceptibility and the epidemic spread of COVID-19. The dynamics of risk by and across exposure settings alongside the variations following the implementation of social distancing interventions are understudied. OBJECTIVE: This study aims to examine the population's trajectory of exposure risk in different settings and its association with SARS-CoV-2 infection across 3 consecutive Omicron epidemic waves in Hong Kong. METHODS: From March to June 2022, invitation letters were posted to 41,132 randomly selected residential addresses for the recruitment of households into a prospective population cohort. Through web-based monthly surveys coupled with email reminders, a representative from each enrolled household self-reported incidents of SARS-CoV-2 infections, COVID-19 vaccination uptake, their activity pattern in the workplace, and daily and social settings in the preceding month. As a proxy of their exposure risk, the reported activity trend in each setting was differentiated into trajectories based on latent class growth analyses. The associations of different trajectories of SARS-CoV-2 infection overall and by Omicron wave (wave 1: February-April; wave 2: May-September; wave 3: October-December) in 2022 were evaluated by using Cox proportional hazards models and Kaplan-Meier analysis. RESULTS: In total, 33,501 monthly responses in the observation period of February-December 2022 were collected from 5321 individuals, with 41.7% (2221/5321) being male and a median age of 46 (IQR 34-57) years. Against an expanding COVID-19 vaccination coverage from 81.9% to 95.9% for 2 doses and 20% to 77.7% for 3 doses, the cumulative incidence of SARS-CoV-2 infection escalated from <0.2% to 25.3%, 32.4%, and 43.8% by the end of waves 1, 2, and 3, respectively. Throughout February-December 2022, 52.2% (647/1240) of participants had worked regularly on-site, 28.7% (356/1240) worked remotely, and 19.1% (237/1240) showed an assorted pattern. For daily and social settings, 4 and 5 trajectories were identified, respectively, with 11.5% (142/1240) and 14.6% (181/1240) of the participants gauged to have a high exposure risk. Compared to remote working, working regularly on-site (adjusted hazard ratio [aHR] 1.47, 95% CI 1.19-1.80) and living in a larger household (aHR 1.12, 95% CI 1.06-1.18) were associated with a higher risk of SARS-CoV-2 infection in wave 1. Those from the highest daily exposure risk trajectory (aHR 1.46, 95% CI 1.07-2.00) and the second highest social exposure risk trajectory (aHR 1.52, 95% CI 1.18-1.97) were also at an increased risk of infection in waves 2 and 3, respectively, relative to the lowest risk trajectory. CONCLUSIONS: In an infection-naive population, SARS-CoV-2 transmission was predominantly initiated at the workplace, accelerated in the household, and perpetuated in the daily and social environments, as stringent restrictions were scaled down. These patterns highlight the phasic shift of exposure settings, which is important for informing the effective calibration of targeted social distancing measures as an alternative to lockdown.

Enforcement of the Use of Digital Contact-Tracing Apps in a Common Law Jurisdiction.

Digital contact-tracing systems have been widely implemented worldwide with different system designs and implementation policies for the purpose of tracking potentially exposed individuals. The use of a digital contact-tracing app in Hong Kong has been mandated for visiting certain premises by legislations. This paper reviewed the regulations promulgated specifically for the prevention and control of COVID-19 and identified those associated with the digital contact-tracing system. A comprehensive search in newspaper databases was performed to explore the enforcement of the mandated use of the digital contact-tracing app. The three facets of regulations in relation to digital contact tracing were examined: duty to disclose information, requirements and directions to businesses, and compulsory testing. The use of digital contact-tracing data for non-public health purposes was also reported. Our analyses showed that prosecution of non-use or the use of fraudulent digital contact-tracing apps was not limited to COVID-19-specific legislations. The flexible approach ensured the enforcement of the use of the digital contact-tracing app, but the judiciary's test must be passed in future cases.

User Experience and Usability of Neumorphism and Gamification User Interface Designs in an HIV Self-Test Referral Program for Men Who Have Sex With Men: Prospective Open-Label Parallel-Group Randomized Controlled Trial.

BACKGROUND: Digital interventions have been applied for promoting HIV prevention and care among men who have sex with men (MSM). As user interface (UI) design plays a role in determining usability and user experience (UX), the intervention outcome could be affected. OBJECTIVE: In this study, we hypothesized that 2 UI design styles, namely gamification and neumorphism, could impact usability and be differentially preferred by distinct groups of MSM. METHODS: A prospective parallel-group open-label randomized controlled trial was conducted in Hong Kong. Eligible participants were adult MSM recruited by the research team or referred by enrolled participants, who followed instructions for performing an HIV self-test and promoted its use within their social network. Participants were randomized in a 1:1 ratio into either a gamification or neumorphism arm, with primarily visual differences in the UI only. The primary outcome was usability measured by the System Usability Scale (SUS) between the 2 arms. Distinct characteristics of promoters in the 2 arms who gave an SUS score of 80 or above were identified. RESULTS: Of 463 MSM registered in the study, 232 and 231 were randomized to the gamification and neumorphism arms, respectively. Excluding those who did not request a self-test kit, data from 218 and 216 participants in the gamification and neumorphism arms, respectively, were analyzed (totally 434 participants). With a median SUS score of 80 overall, participants in the neumorphism arm gave a higher score (P<.001), with a higher proportion giving a promoter-level SUS score (P=.002). Promoters used social media for sex networking (P=.02), used pre-exposure prophylaxis in the preceding year (P=.006), had higher satisfaction in UI design (P<.001), and had made a self-test referral (P=.04). In general, higher usability was recorded among participants who were confident in performing the HIV self-test (P<.001), and this was associated with a promoter-level SUS score in both arms. While no other personal characteristics were associated with promoters in the neumorphism arm, those in the gamification arm had higher HIV-related knowledge (P=.01), preferred a specific partner body image type (P=.03), and progressed toward peer referral by completing online training (P=.04). CONCLUSIONS: Both gamified and neumorphic UI designs were well-accepted by MSM. UX and satisfaction of UI were both crucial in influencing the willingness of MSM to promote the application by referring their peers in the community to participate. The simplistic visual design of neumorphism conferred a more general acceptance in the community, whereas gamification was preferred in certain MSM subcommunities. Appropriate UI/UX design should be considered when developing digital interventions targeting the MSM community. TRIAL REGISTRATION: ClinicalTrials.gov NCT04379206; https://clinicaltrials.gov/ct2/show/NCT04379206.

Hepatitis C Co-infection in People Living With HIV-Epidemiologic Differences Between Men Who Have Sex With Men MSM and Non-MSM.

People living with human immunodeficiency virus (PLHIV) constitute a unique group at higher risk of hepatitis C virus (HCV) co-infection. In light of the diverse profiles of PLHIV, we differentiated between men who have sex with men (MSM) and non-MSM in the characterization of the epidemiologic features of HIV/HCV co-infection. Clinical data of HCV co-infection patients from the HIV specialist clinic in Hong Kong were retrospectively collected in conjunction with their HIV subtypes and HCV genotypes. Logistic regression models were used to identify factors associated with HIV/HCV co-infection in MSM. Survival analysis was performed to compare the time lag between HIV and HCV diagnoses between two groups. Latent class analysis was conducted to describe the features of different classes of co-infections. Four classes of HIV/HCV co-infections were identified: local MSM acquiring HCV after HIV diagnosis, local MSM with HIV/HCV co-diagnoses, local non-MSM, and non-local non-MSM. Accounting for over half of the co-infections, MSM were more likely to be younger, local residents, and associated with HCV genotype 3, compared to genotypes 1 and 6 in non-MSM. Overall, MSM had higher odds of achieving HIV viral suppression and co-diagnosing with a sexually transmitted infection at HCV diagnosis, and having a longer time lag between HIV and HCV diagnoses. Drug injection accounted for a majority of non-MSM HCV infection. There were distinctive epidemiologic differences between MSM and non-MSM co-infected with HIV and HCV, the characteristics of which could inform intervention strategies for achieving HCV micro-elimination.

Regular Testing of HIV and Sexually Transmitted Infections With Self-Collected Samples From Multiple Anatomic Sites to Monitor Sexual Health in Men Who Have Sex With Men: Longitudinal Study.

BACKGROUND: Regular HIV and sexually transmitted infection (STI) testing for men who have sex with men (MSM) is an important means of infection prevention, the adoption of which remains suboptimal in the community. OBJECTIVE: On the hypothesis that engagement plays an important role in sexual health monitoring, this study aimed to pilot-test internet-based HIV and STI testing with self-sampling to enhance engagement of MSM with regular testing. METHODS: This 1-year cohort study was conducted on HIV-negative MSM aged 18 years or older. A designated website was set up to enable participants to make appointments for baseline and follow-up visits at 3-monthly intervals. On-site blood sampling was performed for HIV and syphilis tests, along with self-collection of pharyngeal swabs, rectal swabs, and urine samples for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) testing. Full engagement, as defined by having made at least 3 visits over a 6-12 months' follow-up period, was compared with partial engagement in the bivariable logistic regression model. RESULTS: Between August 2019 and October 2020, 204 MSM were recruited, after the exclusion of 2 baseline HIV-positive MSM. The majority (189/204, 92.7%) were Chinese, the median age was 31 (IQR 26-39) years, and 58.0% (116/200) had experience with pre-exposure prophylaxis (PrEP) at baseline. Full engagement (146/204, 71.6%) was associated with incident STI during the follow-ups (odds ratio [OR] 4.23, 95% CI 1.63-10.94), seeking a medical referral after STI detection (OR 10.25, 95% CI 3.25-29.79), and a synchronized schedule of HIV and STI testing with PrEP visits (OR 51.85, 95% CI 19.30-139.34). No incident HIV was detected in the follow-up period. At baseline, the overall STI (CT, NG, or syphilis) prevalence was 30%, with CT at 18%, NG at 13%, and syphilis at 5%. During follow-up, the incidences were 59.08/100 person-years (py) for any STI, 33.05/100 py for CT, 29.86/100 py for NG, and 10.4/100 py for syphilis. The detection rates of CT and NG in urine samples were lower than with pharyngeal swabs and rectal swabs. The scores for convenience, confidence of correct sampling, and accuracy of self-sampling were high (7 to 8 out of 10). CONCLUSIONS: Both baseline prevalence and incidence of STI were high among MSM engaged in regular testing. A high degree of engagement in regular STI and HIV testing was positively associated with incident STI, history of health-seeking behaviors, and perceived convenience of self-sampling. Self-sampling could be introduced as a means of enhancing engagement in regular HIV and STI testing.

Mass Screening of SARS-CoV-2 With Rapid Antigen Tests in a Receding Omicron Wave: Population-Based Survey for Epidemiologic Evaluation.

BACKGROUND: The COVID-19 Omicron BA.2 epidemic wave in Hong Kong peaked in the first quarter of 2022. Following the implementation of stringent public health measures, the daily number of reported cases fell from over 50,000 to below 2000. Although outbreaks steadily receded, the government rolled out a 3-day "voluntary universal rapid testing" campaign to invite all citizens to self-perform a rapid antigen test (RAT) daily to identify undetected prevalent infections. OBJECTIVE: This study aimed to evaluate the uptake and results of RAT mass screening to estimate the population's residual epidemic burden and assess the risk of further transmission. METHODS: A cross-sectional study comprising an open web-based population-based survey was conducted a week after the RAT campaign. Participants were asked to report their COVID-19 vaccination and infection history and the RAT performance and test result during the period. They were also invited to report their coliving individuals' test performance and results. Reasons for nonuptake were enquired. Testing and positive rates were age-adjusted. Determinants of undergoing RAT were identified using univariable and multivariable logistic regression models. RESULTS: In total, particulars from 21,769 individuals were reported by 8338 participants. The overall age-adjusted testing rate was 74.94% (95% CI 73.71%-76.18%), with over 80% of participants in the age groups between 45-84 years having self-performed RAT during the campaign period. After age-adjustment, 1.03% (95% CI 0.86%-1.21%) of participants tested positive. The positive rates in the age groups between 20-29 years and >84 years exceeded 2%. Taking into account the positive rate and 5819 reported cases during the period, the cases identified in the campaign might account for 7.65% (95% CI 6.47%-9.14%) of all infections. Testers were more likely to be female, older, not previously diagnosed with COVID-19, and have received COVID-19 vaccination. Adjusting for the number of household members, those living with a child aged <12 years and whose household members were also tested were more likely to have self-performed an RAT. Main reasons for not performing an RAT included the absence of symptoms (598/1108, 53.97%), disbelief of the appropriateness of the campaign as an antiepidemic measure (355/1108, 32.04%), and a recent COVID-19 diagnosis (332/1108, 29.96%). CONCLUSIONS: The residual population burden remained substantial in spite of the clear evidence of a receding epidemic wave. Despite caution in generalization to the Hong Kong population, the high participation rate in mass screening indicated that the voluntary RAT was well accepted, making it a feasible option for implementation as a complementary means of public health surveillance.

What makes an optimal delivery for PrEP against HIV: A qualitative study in MSM.

BACKGROUND: Pre-exposure prophylaxis (PrEP) is an effective means of HIV prevention for men who have sex with men (MSM), a key population whose engagement is crucial for achieving effective public health outcomes. An optimal service model would be important in planning the implementation of PrEP in places where such service has not been established. METHODS: A qualitative study was conducted to delineate the attributes of an optimal PrEP service model for MSM in Hong Kong, a city where no formal PrEP programs existed. Twenty purposively sampled MSM who were enrollees of two pilot PrEP projects participated in the semi-structured interviews promoting story-telling. The coded data were thematically analyzed following Grounded Theory approach, focusing on uncovering a typology of the essential attributes of an optimal PrEP service model, and the reasons for such preferences. RESULTS: Participating MSM were all ethnic Chinese and aged 26 to 52 years. All had received PrEP from pilot projects in conjunction with periodic screening of sexually transmitted infections (STI), HIV antibody, and plasma creatinine. Four major themes emerged as regards the attributes of a preferred PrEP service: (i) comprehensiveness of HIV/STI and safety monitoring; (ii) convenient unitary service; (iii) stigma-free PrEP access and protecting confidentiality; and (iv) affordable price. Whereas regular provision of PrEP was acceptable to MSM, unaffordability and related stigma were the anticipated challenges for potential service providers. CONCLUSIONS: The qualitative assessment of MSM's preference for PrEP service delivery has yielded important information on the many facets of a desirable service model.

The differential impacts of early detection and accelerated antiretroviral therapy on the epidemiologic trend of sexually acquired HIV infection in Hong Kong.

OBJECTIVES: To assess impacts of early detection and prompt antiretroviral therapy (ART) on the latest epidemiologic situation to inform intervention strategy. METHODS: We analysed data from two clinical cohorts in Hong Kong where sexual transmission accounted for the majority of HIV infections. The two cohorts comprised patients newly diagnosed in 2007-2008 and 2016-2018 respectively. Secular trend and differences between men who have sex with men (MSM) and heterosexual patients were examined. Predictors of late presentation (defined as CD4 ≤350 or AIDS-defining illness within 3 months of diagnosis) and prolonged interval between diagnosis and ART initiation were assessed by multivariable regressions. RESULTS: There were 1,136 newly diagnosed HIV patients with 644 in the first and 492 in the second cohort, a majority (91.7%) presented with sexually acquired infection. There were less MSM in the first than the second cohort (50.3%% vs 87.8%, χ2 = 117.05, p<0.001). The mean (SD) number of days between diagnosis and ART initiation decreased from 514.3 (516.1) to 61.8 (94.2) days across the two cohorts. Younger age, non-Chinese, outpatient-based service and lower CD4 count were predictors of faster ART initiation in the first but not in the second cohort. Interval between diagnosis and ART initiation became highly uniform among groups in the second cohort. Nearly 60% were classified as late presenters in both cohorts. Heterosexuals (aOR 1.58, 95% CI 1.13-2.19) had a higher risk of late presentation. CONCLUSIONS: There was remarkable improvement in acceleration of ART initiation. Clinical implementation of accelerated ART recommendations has been effective for both MSM and heterosexuals. Late presentation was more marked among heterosexuals and remained a problem. The continued phenomenon of late presentation could offset the epidemiologic gains from accelerated ART initiation.

Mining relationships between transmission clusters from contact tracing data: An application for investigating COVID-19 outbreak.

OBJECTIVE: Contact tracing of reported infections could enable close contacts to be identified, tested, and quarantined for controlling further spread. This strategy has been well demonstrated in the surveillance and control of COVID-19 (coronavirus disease 2019) epidemics. This study aims to leverage contact tracing data to investigate the degree of spread and the formation of transmission cascades composing of multiple clusters. MATERIALS AND METHODS: An algorithm on mining relationships between clusters for network analysis is proposed with 3 steps: horizontal edge creation, vertical edge consolidation, and graph reduction. The constructed network was then analyzed with information diffusion metrics and exponential-family random graph modeling. With categorization of clusters by exposure setting, the metrics were compared among cascades to identify associations between exposure settings and their network positions within the cascade using Mann-Whitney U test. RESULTS: Experimental results illustrated that transmission cascades containing or seeded by daily activity clusters spread faster while those containing social activity clusters propagated farther. Cascades involving work or study environments consisted of more clusters, which had a higher transmission range and scale. Social activity clusters were more likely to be connected, whereas both residence and healthcare clusters did not preferentially link to clusters belonging to the same exposure setting. CONCLUSIONS: The proposed algorithm could contribute to in-depth epidemiologic investigation of infectious disease transmission to support targeted nonpharmaceutical intervention policies for COVID-19 epidemic control.

Comparison between daily and on-demand PrEP (pre-exposure prophylaxis) regimen in covering condomless anal intercourse for men who have sex with men in Hong Kong: A randomized, controlled, open-label, crossover trial.

INTRODUCTION: Both daily and on-demand regimens have been proven effective for pre-exposure prophylaxis (PrEP) against HIV in men who have sex with men (MSM). We aimed to compare the two regimens on their coverage of condomless anal intercourse (CLAI) in MSM. METHODS: A randomized, controlled, open-label, crossover trial was conducted in a teaching hospital in Hong Kong. Participants were sexually active HIV-negative MSM aged 18 years or above with normal renal function and without chronic hepatitis B infection. Oral tenofovir disoproxil fumarate 300 mg/emtricitabine 200 mg (TDF/FTC) tablets were prescribed for PrEP. After a 2-week lead-in with daily TDF/FTC for treatment-naïve MSM for tolerance assessment, participants were randomly assigned in a 1:1 ratio with a block size of four to either daily-first or on-demand-first arm based on the IPERGAY study, for receiving PrEP for 16 weeks, then crossed-over to the alternative regimen for another 16 weeks. The primary outcome was the proportion of days with PrEP-covered CLAI by intention-to-treat analysis. The trial is registered with the CCRB Clinical Trials Registry, CUHK, CUHK_CCRB00606, and is closed to accrual. RESULTS: Between 25 August 2018 and 23 March 2019, 119 eligible participants were assigned to daily-first arm (n = 59) and on-demand-first arm (n = 60) with an 87% overall completion rate (n = 103). With 96% and 54% of days on PrEP during daily and on-demand periods, respectively, the proportion of days with PrEP-covered CLAI between two arms were not statistically different (92% vs. 92%, p = 0.93). About half (47%) were diagnosed with at least one episode of incident sexually transmitted infection. Mild and time-limited adverse events, including diarrhoea, headache, nausea and dizziness, were reported in 37 (31%) and 10 (8%) during the daily and on-demand periods, respectively. At the end of the study, a similar proportion favoured daily or on-demand regimen. CONCLUSIONS: High prevention-effective adherence, as reflected from the coverage of CLAI, was achievable by either daily or on-demand PrEP among MSM, albeit a higher number of tablets taken for daily PrEP. As both regimens were well accepted, a flexible approach adopting either or both regimens with possible switching is warranted in order to suit individual health needs.

Settings of virus exposure and their implications in the propagation of transmission networks in a COVID-19 outbreak.

BACKGROUND: Transmission dynamics of SARS-CoV-2 varied by the settings of virus exposure. Understanding the inter-relationship between exposure setting and transmission networks would provide a basis for informing public health control strategies. METHODS: Surveillance and clinical data from the first wave of COVID-19 outbreaks in Hong Kong were accessed. Twelve exposure setting types were differentiated - household, neighbourhood, eateries, entertainment, parties, shopping, personalised service, workplace, education, worship, healthcare, transport. Clustering was investigated followed by reconstructing the transmission cascades of clustered cases using social networking approach. Linked and unlinked cases were compared in statistical analyses. FINDINGS: Between 23 January and 19 June 2020, 1128 cases were reported. Among 324 cases related to local transmission, 123 clusters comprising two or more epidemiologically linked cases were identified. Linked cases had lower Ct value (p < 0·001) than unlinked cases. Households accounted for 63% of all clusters with half as primary setting, while entertainment accounted for the highest number of primary setting transmission cases. There were altogether 19 cascades involving >1 exposure setting, with a median reproduction number of 3(IQR: 2-4), versus 1(IQR:1-2) for cascades involving a single setting (n = 36 cascades). The longest cascade featured a bar (entertainment) as primary setting, with propagation through 30 non-primary exposure settings from seven setting types, reflecting, propensity for widespread dispersion and difficulty in containment. INTERPRETATION: There was marked heterogeneity in the characteristics of SARS-CoV-2 transmission cascades which differed by exposure setting. Network epidemiological analyses of transmission cascades can be applied as a risk assessment tool in decision-making for calibrating social distancing measures. FUNDING: Health and Medical Research Fund.

Delineation of chemsex patterns of men who have sex with men in association with their sexual networks and linkage to HIV prevention.

BACKGROUND: Previous studies have shown that men who have sex with men (MSM) and who engage in drug use in sexualized contexts (chemsex) were more likely to be HIV positive. Their social networks and adoption of HIV prevention measures have, however, not been fully investigated. We aim to compare the sexual behavior, HIV prevention efforts and social networks of MSM by the intensity and patterns of their drug use. METHODS: Data from respondents of a community-based, cross-sectional survey (PRiSM) conducted among MSM in Hong Kong in 2017 were collected retrospectively. Characteristics of MSM engaged and not engaged in chemsex were compared in logistic regressions, delineated by latent class analysis (LCA) and compared in multinominal logistic regression. FINDINGS: Of 4133 respondents, 3044 were sexually active with an HIV prevalence of 6.5%. The prevalence of chemsex engagement in the preceding 6 months was 12%, after excluding use of poppers or erectile dysfunction agents (EDA) alone. Four types of drug user were identified by LCA: Minimal (mainly poppers), low-threshold (mainly poppers and EDA), medium-threshold (mainly methamphetamine, GHB, poppers and EDA) and intense (extensive use of different types of drug). Medium-threshold and intense drug users were more likely to be HIV positive, be diagnosed with sexually transmitted infections, make gay friends through mobile apps and sex parties, and intend to take pre-exposure prophylaxis (PrEP). Medium-threshold drug users had a more influential role in their social network, as shown by their higher centrality in mobile apps network. CONCLUSION: Chemsex engagement in MSM is significantly associated with HIV infection in Hong Kong. The HIV transmission risk could however be offset by the inclination of MSM belonging to medium-threshold and intense drug users to take PrEP, should the intervention become accessible to the community. Further mobile apps could be a good channel to access MSM who are medium-threshold drug users.