Association of nirmatrelvir-ritonavir with post-acute sequelae and mortality among patients who are immunocompromised with COVID-19 in Hong Kong: a retrospective cohort study.

Background: The effect of nirmatrelvir-ritonavir on post-COVID-19 outcomes for individuals who are immunocompromised is understudied. We aimed to examine the association of nirmatrelvir-ritonavir with post-acute sequelae and mortality among patients who are immunocompromised and admitted to hospital with COVID-19.

Methods: We did a retrospective cohort study using territory-wide electronic health records from the Hong Kong Hospital Authority and Hong Kong Department of Health.

COVID-19 vaccination modified the effect of nirmatrelvir-ritonavir on post-acute mortality and rehospitalization: a retrospective cohort study.

While previous research examined coronavirus disease 2019 (COVID-19) antiviral-vaccine interactions through exploratory subgroup analysis, none specifically designed for examining this interaction or its impact on post-acute outcomes. This study examined the interaction between nirmatrelvir-ritonavir and complete COVID-19 vaccination on reducing the risk of post-acute outcomes among COVID-19 patients. We followed COVID-19 patients hospitalized between 11 March 2022 and 10 October 2023, until 31 October 2023 in Hong Kong.

Association between meteorological variations and the superspreading potential of SARS-CoV-2 infections.

Background: While many investigations examined the association between environmental covariates and COVID-19 incidence, none have examined their relationship with superspreading, a characteristic describing very few individuals disproportionally infecting a large number of people.

Methods: Contact tracing data of all the laboratory-confirmed COVID-19 cases in Hong Kong from February 16, 2020 to April 30, 2021 were used to form the infection clusters for estimating the time-varying dispersion parameter (k), a measure of superspreading potential. Generalized additive models with identity link function were used to examine the association between negative-log k (larger means higher superspreading potential) and the environmental covariates, adjusted with mobility metrics that account for the effect of social distancing measures.

Geographic Targeting of COVID-19 Testing to Maximize Detection in Los Angeles County.

Background: Many severe acute respiratory syndrome coronavirus 2 infections have not been detected, reported, or isolated. For community testing programs to locate the most cases under limited testing resources, we developed and evaluated quantitative approaches for geographic targeting of increased coronavirus disease 2019 testing efforts.

Methods: For every week from December 5, 2021, to July 23, 2022, testing and vaccination data were obtained in ∼340 cities/communities in Los Angeles County, and models were developed to predict which cities/communities would have the highest test positivity 2 weeks ahead.

Effectiveness of BNT162b2 and Sinovac vaccines against the transmission of SARS-CoV-2 during Omicron-predominance in Hong Kong: A retrospective cohort study of COVID-19 cases.

Background: In 2022, SARS-CoV-2 Omicron variants circulated globally, generating concerns about increased transmissibility and immune escape. Hong Kong, having an infection-naive population with a moderate 2-dose vaccine coverage (63% by the end of 2021), experienced a COVID-19 epidemic largely seeded by Omicron BA.2 variants that led to the greatest outbreak in the region to date.

Relationship between antidepressants and severity of SARS-CoV-2 Omicron infection: a retrospective cohort study using real-world data.

Background: Few studies have used real-world data to evaluate the impact of antidepressant use on the risk of developing severe outcomes after SARS-CoV-2 Omicron infection.

Methods: This is a retrospective cohort study using propensity-score matching to examine the relationship between antidepressant use and COVID-19 severity. Inpatient and medication records of all adult COVID-19 patients in Hong Kong during the Omicron-predominated period were obtained.

Estimated preventable COVID-19-associated deaths due to non-vaccination in the United States.

While some studies have previously estimated lives saved by COVID-19 vaccination, we estimate how many deaths could have been averted by vaccination in the US but were not because of a failure to vaccinate. We used a simple method based on a nationally representative dataset to estimate the preventable deaths among unvaccinated individuals in the US from May 30, 2021 to September 3, 2022 adjusted for the effects of age and time. We estimated that at least 232,000 deaths could have been prevented among unvaccinated adults during the 15 months had they been vaccinated with at least a primary series.

Spatio-temporal estimates of HIV risk group proportions for adolescent girls and young women across 13 priority countries in sub-Saharan Africa.

The Global AIDS Strategy 2021-2026 identifies adolescent girls and young women (AGYW) as a priority population for HIV prevention, and recommends differentiating intervention portfolios geographically based on local HIV incidence and individual risk behaviours. We estimated prevalence of HIV risk behaviours and associated HIV incidence at health district level among AGYW living in 13 countries in sub-Saharan Africa. We analysed 46 geospatially-referenced national household surveys conducted between 1999-2018 across 13 high HIV burden countries in sub-Saharan Africa.

Comparing the incubation period, serial interval, and infectiousness profile between SARS-CoV-2 Omicron and Delta variants.

In January 2022, the SARS-CoV-2 Omicron variants initiated major outbreaks and dominated the transmissions in Hong Kong, displacing an earlier outbreak seeded by the Delta variants. To provide insight into the transmission potential of the emerging variants, we aimed to compare the epidemiological characteristics of the Omicron and Delta variants. We analyzed the line-list clinical and contact tracing data of the SARS-CoV-2 confirmed cases in Hong Kong.

Dining-Out Behavior as a Proxy for the Superspreading Potential of SARS-CoV-2 Infections: Modeling Analysis.

Background: While many studies evaluated the reliability of digital mobility metrics as a proxy of SARS-CoV-2 transmission potential, none examined the relationship between dining-out behavior and the superspreading potential of COVID-19.

Objective: We employed the mobility proxy of dining out in eateries to examine this association in Hong Kong with COVID-19 outbreaks highly characterized by superspreading events.

Methods: We retrieved the illness onset date and contact-tracing history of all laboratory-confirmed cases of COVID-19 from February 16, 2020, to April 30, 2021.

Estimation of Vaccine Effectiveness of CoronaVac and BNT162b2 Against Severe Outcomes Over Time Among Patients With SARS-CoV-2 Omicron.

Importance: Few studies have evaluated the waning of vaccine effectiveness against severe outcomes caused by SARS-CoV-2 Omicron infection. Hong Kong is providing inactivated and mRNA vaccines, but the population had limited protection from natural infections before the Omicron variant emerged.

Objective: To examine the change in vaccine effectiveness against hospitalization and mortality due to the Omicron variant over time.

Risk scores for predicting HIV incidence among adult heterosexual populations in sub-Saharan Africa: a systematic review and meta-analysis.

Introduction: Several HIV risk scores have been developed to identify individuals for prioritized HIV prevention in sub-Saharan Africa. We systematically reviewed HIV risk scores to: (1) identify factors that consistently predicted incident HIV infection, (2) review inclusion of community-level HIV risk in predictive models and (3) examine predictive performance.

Methods: We searched nine databases from inception until 15 February 2021 for studies developing and/or validating HIV risk scores among the heterosexual adult population in sub-Saharan Africa.

Characterization of Unlinked Cases of COVID-19 and Implications for Contact Tracing Measures: Retrospective Analysis of Surveillance Data.

Background: Contact tracing and intensive testing programs are essential for controlling the spread of COVID-19. However, conventional contact tracing is resource intensive and may not result in the tracing of all cases due to recall bias and cases not knowing the identity of some close contacts. Few studies have reported the epidemiological features of cases not identified by contact tracing ("unlinked cases") or described their potential roles in seeding community outbreaks.

Changes in Measles Seroprevalence in China After the Launch of Two Provincial Supplementary Immunization Activities During 2009 to 2013.

Background: Supplementary immunization activities (SIAs) have been demonstrated being effective in reducing measles incidence within a short period of time in China, but the effects are short-lived if there is no follow-up SIA with high routine immunization coverage.

Objectives: To assess the change in measles seroprevalence from 2009 to 2013 after the launch of 2 large-scale SIAs within the period.

Methods: Three population-based cross-sectional serologic surveys of measles antibodies were conducted in 2009, 2011 and 2013 in Zhejiang, a province in eastern China, with serologic samples collected from 1541, 896 and 1474 subjects, respectively.

Epidemiological changes in measles infections in southern China between 2009 and 2016: a retrospective database analysis.

Background: The incidence rate of measles in China reached a nadir in 2012 after 2 supplementary immunization activities (SIAs) were undertaken in 2009 and 2010. However, the disease began re-emerging in 2013, with a high prevalence rate observed in 2013-2014 in the southern province of Guangdong. In this study, we assessed the changes that occurred in measles epidemiology during 2009-2016, particularly between 2009 and 2011 (when the influence of the SIAs were in full effect) and between 2012 and 2016 (when this influence subsided).

Early Waning of Maternal Measles Antibodies in Infants in Zhejiang Province, China: A Comparison of Two Cross-Sectional Serosurveys.

In China, children aged <8 months, who were expected to be protected by maternal antibodies before receiving the first dose of measles vaccine, were the age group with the greatest risk of infection in recent years. In this study, we evaluated whether infants yet to be age-eligible for measles vaccine had a sufficient seropositive level of maternal measles antibodies in 2009 and 2013. Blood samples were collected from infants aged <8 months through population-based serological surveys conducted in Zhejiang, China.

Latitudes mediate the association between influenza activity and meteorological factors: A nationwide modelling analysis in 45 Japanese prefectures from 2000 to 2018.

Background: Cold and dry conditions were well-documented as a major determinant of influenza seasonality in temperate countries but the association may not be consistent when the climate in temperate areas is closer to that in sub-tropical areas. We hypothesized latitudes may mediate the association between influenza activity and meteorological factors in 45 Japanese prefectures.

Methods: We used the weekly incidence of influenza-like illness of 45 prefectures from 2000 to 2018 as a proxy for influenza activity in Japan, a temperate country lying off the east coast of Asia.

Association between meteorological variations and activities of influenza A and B across different climate zones: a multi-region modelling analysis across the globe.

Objective: To elucidate the effects of meteorological variations on the activity of influenza A and B in 11 sites across different climate regions.

Methods: Daily numbers of laboratory-confirmed influenza A and B cases from 2011-2015 were collected from study sites where the corresponding daily mean temperature, relative humidity, wind speed and daily precipitation amount were used for boosted regression trees analysis on the marginal associations and the interaction effects.

Results: Cold temperature was a major determinant that favored both influenza A and B in temperate and subtropical sites.

Mathematical modelling of the impact of treating latent tuberculosis infection in the elderly in a city with intermediate tuberculosis burden.

Hong Kong is a high-income city with intermediate tuberculosis (TB) burden primarily driven by endogenous reactivations. A high proportion of remote latently infected people, particularly elderly, hinders the effectiveness of current strategies focusing on passive TB detection. In this study, we developed a mathematical model to evaluate the impact of treating latent TB infection (LTBI) in the elderly in addition to current TB control strategies.

Targeting Adults for Supplementary Immunization Activities of Measles Control in Central China: A Mathematical Modelling Study.

Routine immunizations and supplementary immunization activities (SIAs) have significantly improved measles control over the past two decades in China. Progress towards eliminating measles currently faces multiple challenges as the infection age increases, and adult-targeted SIA strategies are being considered. This study developed an age-stratified susceptible-exposed-infectious-recovered model using a recently published contact matrix to depict measles transmissions between individuals in seven age groups.

Monitoring the age-specificity of measles transmissions during 2009-2016 in Southern China.

Background: Despite several immunization efforts, China saw a resurgence of measles in 2012. Monitoring of transmissions of individuals from different age groups could offer information that would be valuable for planning adequate disease control strategies. We compared the age-specific effective reproductive numbers (R) of measles during 2009-2016 in Guangdong, China.

Interpreting the transmissibility of measles in two different post periods of supplementary immunization activities in Hubei, China.

Although evidence has shown that supplementary immunization activity (SIA) campaigns greatly reduce the incidence of measles, their effects on disease transmissibility have seldom been monitored. A great decrease in the number of cases may be a false signal of early success towards measles elimination to policy makers. By interpreting the transmissibility in two different post-SIA periods in Hubei, China, the current study showed sustained measles transmissions despite a reduced number of cases.