Hepatitis B burden and population immunity in a high endemicity city - a geographically random household epidemiology study for evaluating achievability of elimination.

This study aimed to provide reference for evaluating the achievability of hepatitis B virus (HBV) elimination in a high endemicity city with universal neonatal vaccination in place for over 30 years. Between September 2018 and October 2020, 2085 citizens from 1143 geographically random households in Hong Kong completed a questionnaire and had blood-testing for HBV markers (anti-HBs, HBsAg, anti-HBc, HBeAg). We evaluated the epidemiology and examined factors associated with HBV exposure, vaccination and chronic diseases. The proportion of households with HBsAg positive index participants was 9.2% (95% CI 7.5%-10.9%). The age- and sex-adjusted HBsAg prevalence was 6.3% (95% CI 5.3%-7.4%), compared to >10% in those born in 1960-1970 and among non-local born citizens, and <1% in people born after introduction of neonatal vaccination. Among 155 HBsAg positive participants, 59% were aware of their infection status with 10% on treatment and 10/150 (6.7%) HBeAg positive. More than 40% (872/2064) tested negative for both HBsAg and anti-HBs, contributed by the lack of immunity in older adults and the waning immunity of vaccines. Hong Kong has remained at high-intermediate HBV endemicity state. The moderate level of anti-HBs positivity and very low treatment coverage (10%) among HBsAg positive participants pose challenges for achieving the HBV elimination target.

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.

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.

Effect of prior outbreak work experience to future outbreak responses for nurses in Hong Kong: A cross-sectional study.

Background: During the early phase of the Coronavirus Disease 2019 (COVID-19) epidemic, health care workers had elevated levels of psychological distress. Historical exposure to disease outbreak may shape different pandemic responses among experienced health care workers. Aim: Considering the unique experience of the 2003 SARS outbreak in Hong Kong, this study examined the association between prior epidemic work experience and anxiety levels, and the mediating role of perceived severity of COVID-19 and SARS in nurses. Methods: In March 2020, a cross-sectional survey targeting practising nurses in Hong Kong was conducted during the early phase of the COVID-19 epidemic. The interrelationships among participants' work experience during the SARS outbreak, perceived severity of SARS and COVID-19, and anxiety level were elucidated using structural equation model (SEM). Findings: Of 1,061 eligible nurses, a majority were female (90%) with a median age of 39 years (IQR = 32-49). A significant and negative indirect association was identified between SARS experience and anxiety levels (B=-0.04, p=0.04) in the SEM with a satisfactory fitness (CFI=0.95; RMSEA=0.06). SARS-experienced nurses perceived SARS to be less severe (B=-0.17, p=0.01), translated an equivalent perception to COVID-19 (B=1.29, p<0.001) and resulted in a lower level of anxiety (B=0.19, p<0.001). Conclusions: The less vigorous perception towards the severity of SARS and COVID-19 may explain SARS-experienced nurses' less initial epidemic-induced anxiety. The possible role of outbreak-experienced nurses in supporting outbreak-inexperienced nurses, both emotionally and technically, should be considered when an epidemic commences. Interventions aiming to facilitate the understanding of emerging virus should also be in place.

Compliance and attitudes of blood donors following transitioning from permanent to 12-month deferral of men who have sex with men in Hong Kong.

BACKGROUND AND OBJECTIVES: Blood safety hinges not just on the scientific rationale for deferral period but potential donors' compliance with the prevailing policy. This study aimed to investigate donors' awareness, attitudes and compliance with the two-phased policy implementation of time-limited deferral for men who have sex with men (MSM) in Hong Kong. MATERIALS AND METHODS: Three rounds of questionnaire survey were conducted between July 2017 and June 2019 covering the periods of pre-implementation (Round A), post-implementation without and with pre-donation questionnaire revision (Round B and C). Chi-square test and multivariable regression analysis were performed. RESULTS: Of 3085 donors recruited, 968, 1036 and 1081 completed the surveys in Round A, B and C, respectively. The non-compliance rate of MSM remained stable at 0·6% (3/497), 0·4% (2/551) and 0·5% (3/587) among male donors in Round A, B and C, respectively. Two MSM donors from Round C complying with the prevailing policy were identified. About two-thirds (60·7%) of respondents from Round B and C were unaware of the policy change. Overall, over 80% were either neutral or positive about the change. CONCLUSION: Our study showed a consistently low non-compliance rate of MSM over the three periods. The generally high level of acceptance of time-limited deferral among donors lends support to science-based policy development to protect blood safety. The identification of compliant MSM donors suggests that the 12-month deferral is effective and acceptable to MSM. With a deferral period far exceeding the window period, it is a step towards a more equitable policy.

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.

The double-edged impacts of COVID-19 epidemic on influenza vaccination uptake in nurses in Hong Kong.

BACKGROUND: Worldwide, the COVID-19 pandemic has disrupted influenza seasonality and impacted influenza vaccination behaviours. This study examines the patterns of influenza vaccination uptake in nurses during the pre-pandemic seasons and amidst the pandemic in 2020/21 in subtropical Hong Kong. METHODS: In April 2021, a cross-sectional survey was conducted in practising and student nurses. Six patterns were differentiated by their influenza vaccination status in 2020/21 and preceding five seasons: (a) resistance throughout, (b) negative change, (c) decreased tendency, (d) increased tendency (e) positive change, and (f) adherence throughout. Participants' characteristics and reasons for vaccination/non-vaccination and their associations with each vaccination pattern were explored using multivariable multinomial regression. RESULTS: Among 1323 nurses (88% female with a median age of 39 years), no substantial change in vaccination uptake was noted from 2019/20 (41%) to 2020/21 (42%). Some 4% were positive-changers who were older at age of ≥50 years (aOR 4.77) and more likely to anticipate a reduced risk of severe disease with COVID-19/influenza co-infection following vaccination (aOR 8.76). Negative-changers made up 3% and were more inclined to perceive an unlikelihood of widespread influenza outbreaks amidst the pandemic (aOR 3.67). Some 26 and 43% remained adherent and resistant to influenza vaccination throughout respectively notwithstanding the COVID-19 outbreak. CONCLUSIONS: In contrast to the increased uptake elsewhere, the stable influenza vaccination coverage among nurses in Hong Kong could be explained by the ubiquity of strict physical distancing regulations, which have deterred vaccination in some nurses that offsets the new uptakes induced by the mild COVID-19 outbreaks.

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.

Point-of-care hepatitis C reflex testing and treatment referral in methadone clinic settings in Hong Kong-a pilot study.

Objectives: People who inject drugs (PWID) constitute a population group with a high hepatitis C virus (HCV) burden. With the objectives of assessing the HCV prevalence in PWID and determining the proportion requiring treatment who could be linked to care, this study piloted onsite reflex HCV testing at low threshold methadone clinics, with prompt referral of HCV RNA-positive participants for treatment. Methods: This was a prospective study on methadone clinic attendees in Hong Kong. Questionnaires were completed, finger-prick anti-HCV rapid testing was performed, and positive blood samples were collected for laboratory HCV RNA testing. The proportions of participants along the cascade of HCV care were calculated. Results: In 2021-2022, after 14 evening screening sessions at three methadone clinics, 86 of 354 regular attendees (24%) were recruited. The anti-HCV prevalence was 63% (54/86, 95% confidence interval 52-73%), with 78% (42/54) testing positive for HCV RNA and 79% (33/42) successfully referred. Almost all (31/33) referred participants received direct-acting antiviral (DAA) treatment, 94% (29/31) with full treatment compliance; 55% (16/29) of these compliant participants achieved a sustained virological response, while the remainder had not received post-treatment testing. Conclusions: The use of a simplified testing algorithm in the setting of substitution treatment services, incorporating reflex HCV testing, could be an effective strategy for contributing towards the micro-elimination of HCV in PWID.

Review on the molecular epidemiology of sexually acquired hepatitis C virus infection in the Asia-Pacific region.

INTRODUCTION: Sexual acquisition has emerged as a transmission route for hepatitis C virus (HCV) of growing importance among human immunodeficiency virus (HIV)-positive populations. In Western countries, HCV epidemics have been increasingly detected among men who have sex with men (MSM). This review describes the molecular epidemiology of sexually acquired HCV infection in the Asia-Pacific region. METHODS: A systematic search was performed on PubMed in March 2019. Either abstract or full-text of each publication in the search results was screened for eligibility. Studies from different countries/cities involving eligible cases, who acquired HCV sexually with identified subtype, were synthesized for the evaluation of molecular epidemiology in the Asia-Pacific region. Two large-scale systematic reviews on the genotype distribution of HCV at a population level and among PWID were used as references for comparison. RESULTS AND DISCUSSION: Overall, 13 full-text articles with 549 subjects originating from nine countries/cities were reviewed. A total of five genotypes and 14 subtypes were identified, dominated by subtypes 1b (23.0%), 2a (19.1%) and 3a (29.5%). A majority of the infected cases occurred in HIV-positive MSM. In some places, notably Hong Kong, India and Indonesia, the predominant subtype in sexually acquired HCV infection in MSM was different from that circulating in the general population. Shared transmission networks between people who inject drugs (PWID) and MSM were shown in Australia and New Zealand, whereas overlapping risk elicited from a small number of subjects existed in Tokyo, Taipei and Guangxi. MSM-specific clusters were identified in Hong Kong, Taipei and Hubei. CONCLUSIONS: The distribution of sexually acquired HCV was sparsely scattered across countries/cities in the Asia-Pacific region. The threat of overlapping risk differed by locations, whereas transnational outbreaks remained uncommon. The paucity of information has hindered progress with comprehensive assessment in the Asia-Pacific region, where seroprevalence of HCV among HIV-positive MSM was relatively high.