Global SARS-CoV-2 seroprevalence from January 2020 to April 2022: A systematic review and meta-analysis of standardized population-based studies.

BACKGROUND: Our understanding of the global scale of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection remains incomplete: Routine surveillance data underestimate infection and cannot infer on population immunity; there is a predominance of asymptomatic infections, and uneven access to diagnostics. We meta-analyzed SARS-CoV-2 seroprevalence studies, standardized to those described in the World Health Organization's Unity protocol (WHO Unity) for general population seroepidemiological studies, to estimate the extent of population infection and seropositivity to the virus 2 years into the pandemic. METHODS AND FINDINGS: We conducted a systematic review and meta-analysis, searching MEDLINE, Embase, Web of Science, preprints, and grey literature for SARS-CoV-2 seroprevalence published between January 1, 2020 and May 20, 2022. The review protocol is registered with PROSPERO (CRD42020183634). We included general population cross-sectional and cohort studies meeting an assay quality threshold (90% sensitivity, 97% specificity; exceptions for humanitarian settings). We excluded studies with an unclear or closed population sample frame. Eligible studies-those aligned with the WHO Unity protocol-were extracted and critically appraised in duplicate, with risk of bias evaluated using a modified Joanna Briggs Institute checklist. We meta-analyzed seroprevalence by country and month, pooling to estimate regional and global seroprevalence over time; compared seroprevalence from infection to confirmed cases to estimate underascertainment; meta-analyzed differences in seroprevalence between demographic subgroups such as age and sex; and identified national factors associated with seroprevalence using meta-regression. We identified 513 full texts reporting 965 distinct seroprevalence studies (41% low- and middle-income countries [LMICs]) sampling 5,346,069 participants between January 2020 and April 2022, including 459 low/moderate risk of bias studies with national/subnational scope in further analysis. By September 2021, global SARS-CoV-2 seroprevalence from infection or vaccination was 59.2%, 95% CI [56.1% to 62.2%]. Overall seroprevalence rose steeply in 2021 due to infection in some regions (e.g., 26.6% [24.6 to 28.8] to 86.7% [84.6% to 88.5%] in Africa in December 2021) and vaccination and infection in others (e.g., 9.6% [8.3% to 11.0%] in June 2020 to 95.9% [92.6% to 97.8%] in December 2021, in European high-income countries [HICs]). After the emergence of Omicron in March 2022, infection-induced seroprevalence rose to 47.9% [41.0% to 54.9%] in Europe HIC and 33.7% [31.6% to 36.0%] in Americas HIC. In 2021 Quarter Three (July to September), median seroprevalence to cumulative incidence ratios ranged from around 2:1 in the Americas and Europe HICs to over 100:1 in Africa (LMICs). Children 0 to 9 years and adults 60+ were at lower risk of seropositivity than adults 20 to 29 (p < 0.001 and p = 0.005, respectively). In a multivariable model using prevaccination data, stringent public health and social measures were associated with lower seroprevalence (p = 0.02). The main limitations of our methodology include that some estimates were driven by certain countries or populations being overrepresented. CONCLUSIONS: In this study, we observed that global seroprevalence has risen considerably over time and with regional variation; however, over one-third of the global population are seronegative to the SARS-CoV-2 virus. Our estimates of infections based on seroprevalence far exceed reported Coronavirus Disease 2019 (COVID-19) cases. Quality and standardized seroprevalence studies are essential to inform COVID-19 response, particularly in resource-limited regions.

Uptake of hepatitis B antiviral treatment: A panel data analysis of 31 provinces in China (2013-2020).

BACKGROUND: China has made substantial efforts aimed to promote the uptake of antiviral treatment of hepatitis B (HB). It is unclear whether these policies achieved the desired impact. This study adopted medicines procurement data from 31 provinces to generate the first evidence about the number of standard antiviral treatment of HB overtime at both national and provincial levels in China. METHODS: We performed the panel data analyses and quasi-experimental design with the time-varying difference-in-difference method combined with the event study approach to estimate the uptake of HB antiviral treatment before and after national policy changes. RESULTS: The overall trends in HB antiviral treatment at the national level increased incrementally during 2013-2020. There was 2.8862 million 12-month (person-year) antiviral standard treatment in 2020, which was only 8.93% of the eligible people estimated to need treatment. The number of monthly antiviral standard treatment increased by 42.4% (p = .001) overall following the nationwide adoption of the '4 + 7' pilot-pooled procurement prices in 2019, which brought substantial price reduction of core antivirals. CONCLUSIONS: A low treatment rate is a critical issue in reaching the elimination of viral hepatitis as a public health threat in China. Affordability is an important but not the only factor that determines the uptake of hepatitis treatment. Further scaling up and acceleration of treatment uptake will need strategies improving public awareness of HB, strengthening diagnosis, linking people who are infected to chronic care, reducing loss to follow-up, and ensuring people who are eligible get timely treatment.

Progress towards achieving viral hepatitis B and C elimination in the Asia and Pacific region: Results from modelling and global reporting.

In 2016, Asia and Pacific countries endorsed action plans for reaching viral hepatitis elimination targets set in the Global Health Sector Strategy (GHSS) for Viral Hepatitis 2016-2021. We examine the region's progress by modelling disease burden and constructing the cascade of care. Between 2015 and 2020, chronic HBV prevalence declined from 4.69% to 4.30%, and HCV prevalence declined from 0.64% to 0.58%. The region achieved the 2020 target of 30% incidence reduction for HBV, whereas HCV incidence declined by 6%. Hepatocellular carcinoma incidence for HBV and HCV increased by 9% and 7%, respectively. Liver-related deaths from HBV rose by 8%, and mortality attributable to HCV plateaued. Large testing and treatment gaps remained in 2019: only 13% of chronic HBV infections were diagnosed and 25% treated; 21% of chronic HCV infection were diagnosed and 11% treated. Viral hepatitis must become national priority with adequate funding to reach elimination goals by 2030.

High prevalence of pre-treatment HIV drug resistance in Papua New Guinea: findings from the first nationally representative pre-treatment HIV drug resistance study.

BACKGROUND: Determining the prevalence of pre-treatment HIV drug resistance (PDR) is important to assess the effectiveness of first-line therapies. To determine PDR prevalence in Papua New Guinea (PNG), we conducted a nationally representative survey. METHODS: We used a two-stage cluster sampling method to recruit HIV treatment initiators with and without prior exposure to antiretroviral therapies (ART) in selected clinics. Dried blood spots were collected and tested for PDR. RESULTS: A total of 315 sequences were available for analysis. The overall PDR prevalence rate was 18.4% (95% CI 13.8-24.3%). The prevalence of PDR to non-nucleoside analog reverse-transcriptase inhibitors (NNRTIs) was 17.8% (95% CI 13.6-23.0%) and of PDR to nucleoside reverse transcriptase inhibitors (NRTIs) was 6.3% (95% CI 1.6-17.1%). The PDR prevalence rate among people reinitiating ART was 42.4% (95% CI 29.1-56.4%). CONCLUSIONS: PNG has a high PDR prevalence rate, especially to NNRTI-based first-line therapies. Our findings suggest that removing NNRTIs as part of first-line treatment is warranted and will lead to improving viral suppression rates in PNG.

High HIV Prevalence and Risk Among Male Clients of Female Sex Workers in Hanoi and Ho Chi Minh City, Vietnam.

In Vietnam's concentrated HIV epidemic, female sex workers (FSWs) are at increased risk for acquiring and transmitting HIV, largely through their male clients. A high proportion of males in Vietnam report being clients of FSWs. Studying HIV-related risk factors and prevalence among male clients is important, particularly given the potential for male clients to be a 'bridge' of HIV transmission to the more general population or to sex workers. Time-location sampling was used to identify FSW in Hanoi and Ho Chi Minh City, Vietnam's largest cities, in 2013-2014. Recruited FSWs were asked to refer one male client to the study. Demographic and risk behavior data were collected from FSWs and male clients by administered questionnaires. Biologic specimens collected from male clients were tested for HIV and opiates. Sampling weights, calculated based on the FSWs probability of being selected for enrolment, were applied to prevalence estimates for both FSWs and male clients. Logistic regression models were developed to obtain odds ratios for HIV infection among male clients. A total of 804 male clients were enrolled. Overall, HIV prevalence among male clients was 10.2%; HIV prevalence was 20.7% (95% confidence interval (CI) 15.0-27.9%) among those reporting a history of illegal drug use and 32.4% (95% CI 20.2-47.7%) among those with opioids detected in urine. HIV prevalence among male clients did not differ across 'bridging' categories defined by condom use with FSWs and regular partners over the previous 6 months. HIV among male clients was associated with a reported history of illegal drug use (OR 3.76; 95% CI 1.87-7.56), current opioid use (OR 2.55; 95% CI 1.02-6.36), and being referred by an FSW who self-reported as HIV-positive (OR 5.37; 95% CI 1.46-19.75). Self-reported HIV prevalence among enrolled FSWs was 2.8%. Based on HIV test results of male clients and self-reported status from FSWs, an estimated 12.1% of male client-FSW pairs were sero-discordant. These results indicate high HIV prevalence among male clients of FSWs, particularly among those with a history of drug use. Programs to expand HIV testing, drug-use harm reduction, and HIV treatment for HIV-infected male clients of FSWs should be considered as key interventions for controlling the HIV epidemic in Vietnam.

Sampling Males Who Inject Drugs in Haiphong, Vietnam: Comparison of Time-Location and Respondent-Driven Sampling Methods.

Accurate measurements of HIV prevalence and associated risk factors among hidden and high-risk groups are vital for program planning and implementation. However, only two sampling methods are purported to provide representative estimates for populations without sampling frames: time-location sampling (TLS) and respondent-driven sampling (RDS). Each method is subject to potential biases and questionable reliability. In this paper, we evaluate surveys designed to estimate HIV prevalence and associated risk factors among people who inject drugs (PWID) sampled through TLS versus RDS. In 2012, males aged ≥16 years who reported injecting drugs in the previous month and living in Haiphong, Vietnam, were sampled using TLS or RDS. Data from each survey were analyzed to compare HIV prevalence, related risk factors, socio-demographic characteristics, refusal estimates, and time and expenditures for field implementation. TLS (n = 432) and RDS (n = 415) produced similarly high estimates for HIV prevalence. Significantly lower proportions of PWID sampled through RDS received methadone treatment or met an outreach worker. Refusal estimates were lower for TLS than for RDS. Total expenditures per sample collected and number of person-days of staff effort were higher for TLS than for RDS. Both survey methods were successful in recruiting a diverse sample of PWID in Haiphong. In Vietnam, surveys of PWID are conducted throughout the country; although the refusal estimate was calculated to be much higher for RDS than TLS, RDS in Haiphong appeared to sample PWID with less exposure to services and required fewer financial and staff resources compared with TLS.

Knowledge, attitudes, practices and prevalence of hepatitis B and C and hepatitis B vaccination coverage among public sector healthcare workers in Cambodia.

Healthcare workers (HCWs) are a key population at high risk for hepatitis B (HBV) and hepatitis C (HCV) infections. We aim to study HBV vaccination coverage, seroprevalence, knowledge, attitudes, and practices towards HBV and HCV infections among HCWs in public sector in Cambodia. A nationally representative cross-sectional study was implemented in 2019, among Cambodian HCWs. A standardized questionnaire was administered to randomly selected HCWs whose blood was then sampled. We used univariate and multivariate regression to determine predictors of outcomes. Among 755 participants, we found 4.9% positive HBsAg and 2.3% positive anti-HCV Ab. HBV vaccination coverage was 59.3%. Lack of knowledge was found on the route of transmission, HBV vaccination, diagnosis and treatment of HBV and HCV. 67% of HCWs thought that all patients should be screened for HBV and HCV and about 30% of them would refuse to take care of infected patients. 58% of HCWs always recapped the needle after use. In univariate analysis, older age-group (> 50 years) is more likely to have positive anti-HCV (OR: 9.48; 95% CI: 2.36-38.18). HCWs who were younger, female or having higher education or having ever been tested, were more likely to have gotten HBV vaccinated. Multivariate analysis reconfirmed these predictors of getting vaccinated. Study findings indicated an urgent need of a national policy for Cambodian HCWs given the high prevalence of hepatitis among this group. Policy should include an effective in-service training program to improve knowledge and practices, a testing and vaccination program for HCWs and it should emphasize stigma intervention towards people living with HBV/HCV.

Estimating Asymptomatic and Symptomatic Transmission of the COVID-19 First Few Cases in Selenge Province, Mongolia.

BACKGROUND: Following the first locally transmitted case in Sukhbaatar soum, Selenge Province, we aimed to investigate the ultimate scale of the epidemic in the scenario of uninterrupted transmission. METHODS: This was a prospective case study following the locally modified WHO FFX cases generic protocol. A rapid response team collected data from November 14 to 29, 2020. We created a stochastic process to draw many transmission chains from this greater distribution to better understand and make inferences regarding the outbreak under investigation. RESULTS: The majority of the cases involved household transmissions (35, 52.2%), work transmissions (20, 29.9%), index (5, 7.5%), same apartment transmissions (2, 3.0%), school transmissions (2, 3.0%), and random contacts between individuals transmissions (1, 1.5%). The posterior means of the basic reproduction number of both the asymptomatic cases R 0 Asy $$ {R}_0^{Asy} $$ and the presymptomatic cases R 0 Pre $$ {R}_0^{Pre} $$ (1.35 [95% CrI 0.88-1.86] and 1.29 [95% CrI 0.67-2.10], respectively) were lower than that of the symptomatic cases (2.00 [95% Crl 1.38-2.76]). CONCLUSION: Our study highlights the heterogeneity of COVID-19 transmission across different symptom statuses and underscores the importance of early identification and isolation of symptomatic cases in disease control. Our approach, which combines detailed contact tracing data with advanced statistical methods, can be applied to other infectious diseases, facilitating a more nuanced understanding of disease transmission dynamics.

WHO's Investigations and Studies, Unity Studies: A global initiative creating equitable opportunities for enhanced surveillance, operational research, capacity building, and global knowledge sharing.

The World Health Organization's Unity Studies global initiative provides a generic preparedness and readiness framework for conducting detailed investigations and epidemiological studies critical for the early and ongoing assessment of emerging respiratory pathogens of pandemic potential. During the COVID-19 pandemic, the initiative produced standardized investigation protocols and supported Member States to generate robust and comparable data to inform public health decision making. The subsequent iteration of the initiative is being implemented to develop revised and new investigation protocols, implementation toolkits and work to build a sustainable global network of sites, enabling the global community to be better prepared for the next emerging respiratory pathogen with epidemic or pandemic potential.

Global reporting of progress towards elimination of hepatitis B and hepatitis C.

BACKGROUND: The 69th World Health Assembly endorsed the global health sector strategy on viral hepatitis to eliminate viral hepatitis as a public health threat by 2030. Achieving and measuring the 2030 targets requires a substantial increase in the capacity to test and treat viral hepatitis infections and a mechanism to monitor the progress of hepatitis elimination. This study aimed to identify the gaps in data availability or quality and create a new mechanism to monitor the progress of hepatitis elimination. METHODS: In 2020, using a questionnaire, we collected empirical, systematic, modelled, or surveyed data-reported by WHO country and WHO regional offices-on indicators of progress towards elimination of viral hepatitis, including burden of infection, incidence, mortality, and the cascade of care, and validated these data. FINDINGS: WHO received officially validated country-provided data from 130 countries or territories, and used partner-provided data for 70 countries or territories. We estimated that in 2019, globally, 295·9 million (3·8%) people were living with chronic hepatitis B virus (HBV) infection and 57·8 million (0·8%) people were living with chronic hepatitis C virus (HCV) infection. Globally, there were more than 3·0 million new infections with HBV and HCV and more than 1·1 million deaths due to the viruses in 2019. In 2019, 30·4 million (95% CI 24·3-38·0) individuals living with hepatitis B knew their infection status and 6·6 million (5·3-8·3) people diagnosed with hepatitis B received treatment. Among people with HCV infection, 15·2 million (95% CI 12·1-19·0) had been diagnosed between 2015 and 2019, and 9·4 million (7·5-11·7) people diagnosed with hepatitis C infection were treated with direct-acting antiviral drugs between 2015 and 2019. INTERPRETATION: There has been notable global progress towards hepatitis elimination. In 2019, 30·4 million (10·3%) people living with hepatitis B knew their infection status, which was slightly higher than in 2015 (22·0 million; 9·0%), and 6·6 million (22·7%) of those diagnosed with hepatitis B received treatment, compared with 1·7 million (8·0%) in 2015. Mortality from hepatitis C has declined since 2019, driven by an increase in HCV treatment ten times that of the strategy baseline. However, an estimated 89·7% of HBV infections and 78·6% of HCV infections remain undiagnosed. A new global strategy for 2022-30, based on these new estimates, should be implemented urgently to scale up the screening and treatment of viral hepatitis. FUNDING: World Health Organization.

SARS-CoV-2 seroepidemiology in Mongolia, 2020-2021: a longitudinal national study.

Background: The COVID-19 pandemic has global impacts but is relatively understudied in developing countries. Mongolia, a lower-middle-income country, instituted strict control measures in early 2020 and avoided widespread transmission until vaccines became available in February, 2021. Mongolia achieved its 60% vaccination coverage goal by July 2021. We investigated the distribution and determinants of SARS-CoV-2 seroprevalence in Mongolia over 2020 and 2021. Methods: We performed a longitudinal seroepidemiologic study aligned with WHO's Unity Studies protocols. We collected data from a panel of 5000 individuals in four rounds between October 2020 and December 2021. We selected participants through local health centres across Mongolia by age-stratified multi-stage cluster sampling. We tested serum for the presence of total antibodies against SARS-CoV-2 receptor-binding domain, and levels of anti-SARS-CoV-2 spike IgG and neutralising antibodies. We linked participant data with national mortality, COVID-19 case, and vaccination registries. We estimated population seroprevalence and vaccine uptake, as well as unvaccinated population prior-infection prevalence. Findings: At the final round in late 2021, 82% (n = 4088) of participants completed follow-up. Estimated seroprevalence increased from 1.5% (95% CI: 1.2-2.0), to 82.3% (95% CI: 79.5-84.8) between late-2020 and late-2021. At the final round an estimated 62.4% (95% CI: 60.2-64.5) of the population were vaccinated, and of the unvaccinated population 64.5% (95% CI: 59.7-69.0) had been infected. Cumulative case ascertainment in the unvaccinated was 22.8% (95% CI: 19.1%-26.9%) and the overall infection-fatality ratio was 0.100% (95% CI: 0.088-0.124). Health workers had higher odds for being COVID-19 confirmed cases at all rounds. Males (1.72 (95% CI: 1.33-2.22)) and adults aged 20 and above (12.70 (95% CI: 8.14-20.26)) had higher odds for seroconverting by mid-2021. Among the seropositive, 87.1% (95% CI: 82.3%-90.8%) had SARS-CoV-2 neutralising antibodies by late 2021. Interpretation: Our study enabled tracking of SARS-CoV-2 serological markers in the Mongolian population over one year. We found low SARS-CoV-2 seroprevalence in 2020 and early 2021, with seropositivity increasing over a 3-month interval in 2021 due to vaccine roll out and rapid infection of most of the unvaccinated population. Despite high seroprevalence in Mongolia amongst both vaccinated and unvaccinated individuals by end-2021, the SARS-CoV-2 Omicron immune escape variant caused a substantial epidemic. Funding: World Health Organization, WHO UNITY Studies initiative, with funding by the COVID-19 Solidarity Response Fund and the German Federal Ministry of Health (BMG) COVID-19 Research and development. The Ministry of Health, Mongolia partially funded this study.

Systematic Review of Hepatitis C Virus Prevalence in the WHO Western Pacific Region.

BACKGROUND: This review aimed to identify hepatitis C virus (HCV) prevalence estimates among the general population and six key populations (people who inject drugs, men who have sex with men, sex workers, prisoners/detainees, Indigenous people, and migrants) in the World Health Organization Western Pacific Region (WHO WPR). METHODS: Original research articles published between 2016 and 2020 were identified from bibliographic databases. Publications were retrieved, replicas removed, and abstracts screened. Retained full texts were assessed and excluded if inclusion criteria were not met. Methodological quality was assessed using the Johanna Briggs Institute critical appraisal checklist for prevalence data. Data on HCV exposure and active infection were extracted and aggregated and forest plots generated for each population by country. RESULTS: There were no HCV prevalence estimates in any population for more than half of WPR countries and territories. Among the 76 estimates, 97% presented prevalence of exposure and 33% prevalence of active infection. General population viraemic prevalence was 1% or less, except in Mongolia. Results confirm the endemic nature of HCV among people who inject drugs, with estimates of exposure ranging from 30% in Cambodia to 76% in Hong Kong. CONCLUSIONS: Countries require detailed knowledge of HCV prevalence in diverse populations to evaluate the impact of efforts to support WHO HCV elimination goals. Results provide baseline estimates from which to monitor and evaluate progress and by which to benchmark future elimination efforts.

Eliminate Hepatitis C as a Public Health Threat: A Narrative Review of Strategies, Gaps, and Opportunities for China.

INTRODUCTION: As a country that is heavily burdened by hepatitis C, China's successful responses to this public health threat have significant implications for the achievement of the global elimination goal. METHODS: This article reviews China's strategies for prevention, screening, diagnosis, access to direct-acting antiviral agents (DAA) therapy, and patient management of hepatitis C. It also analyses the major challenges and summarizes the valuable successful international experiences that have implications for China to achieve the elimination goal. RESULTS: To promote the achievement of elimination, China has taken a series of proactive measures to promote the prevention and treatment of hepatitis C. Compared with other middle-income countries, there is still much room for China to achieve universal screening, diagnosis and treatment based on a streamlined disease management procedure. A stronger role of primary care in an integrated healthcare delivery system and integration of hepatitis C with other infectious disease programs should also be the focus of China's efforts. CONCLUSIONS: As a developing country with a large population, a "micro-elimination" strategy with focused screening and proactive diagnosis and treatment for the vulnerable population may be a more practical approach to eliminating hepatitis C in China. Continued efforts are needed to fully overcome the intellectual property barriers of sofosbuvir for forming the more competitive pan-genotype DAA combinations based on the locally developed DAAs. Meanwhile, the safety net for patients in economic hardship needs to be further strengthened. More importantly, it is necessary to promote patients' willingness and compliance with standard treatment through increased awareness of hepatitis C. The development of an integrated healthcare delivery system, a disease management procedure which is suitable for primary care, and full compliance of the primary care providers are also important to achieve effective cascade care management.

Early epidemiological investigations: World Health Organization UNITY protocols provide a standardized and timely international investigation framework during the COVID-19 pandemic.

BACKGROUND: The declaration of Coronavirus disease 2019 (COVID-19) as a Public Health Emergency of International Concern (PHEIC) on 30 January 2020 required rapid implementation of early investigations to inform appropriate national and global public health actions. METHODS: The suite of existing pandemic preparedness generic epidemiological early investigation protocols was rapidly adapted for COVID-19, branded the 'UNITY studies' and promoted globally for the implementation of standardized and quality studies. Ten protocols were developed investigating household (HH) transmission, the first few cases (FFX), population seroprevalence (SEROPREV), health facilities transmission (n = 2), vaccine effectiveness (n = 2), pregnancy outcomes and transmission, school transmission, and surface contamination. Implementation was supported by WHO and its partners globally, with emphasis to support building surveillance and research capacities in low- and middle-income countries (LMIC). RESULTS: WHO generic protocols were rapidly developed and published on the WHO website, 5/10 protocols within the first 3 months of the response. As of 30 June 2021, 172 investigations were implemented by 97 countries, of which 62 (64%) were LMIC. The majority of countries implemented population seroprevalence (71 countries) and first few cases/household transmission (37 countries) studies. CONCLUSION: The widespread adoption of UNITY protocols across all WHO regions indicates that they addressed subnational and national needs to support local public health decision-making to prevent and control the pandemic.

Transmission of SARS-CoV-2 in standardised first few X cases and household transmission investigations: A systematic review and meta-analysis.

We aimed to estimate the household secondary infection attack rate (hSAR) of SARS-CoV-2 in investigations aligned with the WHO Unity Studies Household Transmission Investigations (HHTI) protocol. We conducted a systematic review and meta-analysis according to PRISMA 2020 guidelines. We searched Medline, Embase, Web of Science, Scopus and medRxiv/bioRxiv for "Unity-aligned" First Few X cases (FFX) and HHTIs published 1 December 2019 to 26 July 2021. Standardised early results were shared by WHO Unity Studies collaborators (to 1 October 2021). We used a bespoke tool to assess investigation methodological quality. Values for hSAR and 95% confidence intervals (CIs) were extracted or calculated from crude data. Heterogeneity was assessed by visually inspecting overlap of CIs on forest plots and quantified in meta-analyses. Of 9988 records retrieved, 80 articles (64 from databases; 16 provided by Unity Studies collaborators) were retained in the systematic review; 62 were included in the primary meta-analysis. hSAR point estimates ranged from 2% to 90% (95% prediction interval: 3%-71%; I 2 = 99.7%); I 2 values remained >99% in subgroup analyses, indicating high, unexplained heterogeneity and leading to a decision not to report pooled hSAR estimates. FFX and HHTI remain critical epidemiological tools for early and ongoing characterisation of novel infectious pathogens. The large, unexplained variance in hSAR estimates emphasises the need to further support standardisation in planning, conduct and analysis, and for clear and comprehensive reporting of FFX and HHTIs in time and place, to guide evidence-based pandemic preparedness and response efforts for SARS-CoV-2, influenza and future novel respiratory viruses.

Regional progress towards hepatitis C elimination in the Western Pacific Region, 2015-2020.

Chronic hepatitis C (HCV) infection is a major global public health threat and in 2019 there were an estimated 58 million infected globally and 290,000 deaths. Elimination of viral hepatitis B/C as a public health threat by 2030 is defined as a 90% incidence reduction and a 65% mortality reduction. The Western Pacific region is one of the most affected regions with 10 million people living with HCV, one-fifth of the global burden. We review progress towards HCV elimination in the Western Pacific region since 2015. Key developments in the region, which comprises of 37 high-and-middle-income countries, include the following: 20 countries have national hepatitis action plans, 19 have conducted recent disease burden and investment cases, 10 have scaled-up hepatitis services at primary health care level, and in 11 countries, domestic financing including social health insurance support DAA costs. We highlight six countries' experience in navigating the path towards HCV elimination: Cambodia, China, Malaysia, Mongolia, Philippines, and Viet Nam. Future initiatives to accelerate elimination are expanding access to community-based testing using HCV point-of-care tests among at-risk and general populations; adopting decentralized and integrated HCV one-stop services at harm reduction sites, detention settings and primary care; expanding treatment to include children and adolescents; address stigma and discrimination; and ensuring sustainable financing through domestic resources to scale-up testing, treatment and prevention. The COVID-19 pandemic has a significant impact on hepatitis response across the region on community and facility-based testing, treatment initiation, monitoring and cancer screening, which is projected to delay elimination goals.

Understanding COVID-19 dynamics and the effects of interventions in the Philippines: A mathematical modelling study.

BACKGROUND: COVID-19 initially caused less severe outbreaks in many low- and middle-income countries (LMIC) compared with many high-income countries, possibly because of differing demographics, socioeconomics, surveillance, and policy responses. Here, we investigate the role of multiple factors on COVID-19 dynamics in the Philippines, a LMIC that has had a relatively severe COVID-19 outbreak. METHODS: We applied an age-structured compartmental model that incorporated time-varying mobility, testing, and personal protective behaviors (through a "Minimum Health Standards" policy, MHS) to represent the first wave of the Philippines COVID-19 epidemic nationally and for three highly affected regions (Calabarzon, Central Visayas, and the National Capital Region). We estimated effects of control measures, key epidemiological parameters, and interventions. FINDINGS: Population age structure, contact rates, mobility, testing, and MHS were sufficient to explain the Philippines epidemic based on the good fit between modelled and reported cases, hospitalisations, and deaths. The model indicated that MHS reduced the probability of transmission per contact by 13-27%. The February 2021 case detection rate was estimated at ~8%, population recovered at ~9%, and scenario projections indicated high sensitivity to MHS adherence. INTERPRETATION: COVID-19 dynamics in the Philippines are driven by age, contact structure, mobility, and MHS adherence. Continued compliance with low-cost MHS should help the Philippines control the epidemic until vaccines are widely distributed, but disease resurgence may be occurring due to a combination of low population immunity and detection rates and new variants of concern.

Sustaining effective COVID-19 control in Malaysia through large-scale vaccination.

INTRODUCTION: As of 3rd June 2021, Malaysia is experiencing a resurgence of COVID-19 cases. In response, the federal government has implemented various non-pharmaceutical interventions (NPIs) under a series of Movement Control Orders and, more recently, a vaccination campaign to regain epidemic control. In this study, we assessed the potential for the vaccination campaign to control the epidemic in Malaysia and four high-burden regions of interest, under various public health response scenarios. METHODS: A modified susceptible-exposed-infectious-recovered compartmental model was developed that included two sequential incubation and infectious periods, with stratification by clinical state. The model was further stratified by age and incorporated population mobility to capture NPIs and micro-distancing (behaviour changes not captured through population mobility). Emerging variants of concern (VoC) were included as an additional strain competing with the existing wild-type strain. Several scenarios that included different vaccination strategies (i.e. vaccines that reduce disease severity and/or prevent infection, vaccination coverage) and mobility restrictions were implemented. RESULTS: The national model and the regional models all fit well to notification data but underestimated ICU occupancy and deaths in recent weeks, which may be attributable to increased severity of VoC or saturation of case detection. However, the true case detection proportion showed wide credible intervals, highlighting incomplete understanding of the true epidemic size. The scenario projections suggested that under current vaccination rates complete relaxation of all NPIs would trigger a major epidemic. The results emphasise the importance of micro-distancing, maintaining mobility restrictions during vaccination roll-out and accelerating the pace of vaccination for future control. Malaysia is particularly susceptible to a major COVID-19 resurgence resulting from its limited population immunity due to the country's historical success in maintaining control throughout much of 2020.

SARS-CoV-2 seroprevalence in Mongolia: Results from a national population survey.

BACKGROUND: With the global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in early 2020, Mongolia implemented rapid emergency measures and did not report local transmission until November 2020. We conducted a national seroprevalence survey to monitor the burden of SARS-CoV-2 in Mongolia in the months surrounding the first local transmission. METHODS: During October-December 2020, participants were randomly selected using age stratification and invited for interviews and blood samples at local primary health centres. We screened for total SARS-CoV-2 antibodies, followed by two-step quantitative SARS-CoV-2 IgG serology tests for positive samples. Weighted and test-adjusted seroprevalences were estimated. We used chi-square, Fisher's exact and other tests to identify variables associated with seropositivity. FINDINGS: A total of 5000 subjects were enrolled. We detected SARS-CoV-2 IgG antibodies in 72 samples. Crude seroprevalence of SARS-CoV-2 antibodies was 1·44% (95%CI,1·21-1·67). Population weighted and test-adjusted seroprevalences were 1·36% (95%CI,1·11-1·63) and 1·45% (95%CI,1·11-1·63), respectively. Age, sex, geographical, and occupational factors were not associated with seropositivity (p>0·05). Symptoms and signs within past 3 months and seropositivity were not associated at the time of the survey (p>0·05). INTERPRETATION: SARS-CoV-2 seroprevalence in Mongolia was low in the first year of the pandemic potentially due to strong public health measures, including border restrictions, educational facilities closure, earlier adoption of mask-wearing and others. Our findings suggest large-scale community transmission could not have occurred up to November 2020 in Mongolia. Additional serosurveys are needed to monitor the local pandemic dynamic and estimate how far from herd immunity Mongolia will be following-up with vaccination programme in 2021 and 2022. FUNDING: World Health Organisation, WHO UNITY Studies initiative, with funding by the COVID-19 Solidarity Response Fund and the German Federal Ministry of Health (BMG) COVID-19 Research and development. TRANSLATION: Cyrillic and Traditional Mongolian translation of abstract is available on appendix section.

Increasing HIV prevalence and injection drug use among men who have sex with men in Ho Chi Minh City, Vietnam.

Vietnam has been conducting HIV/sexually transmitted infection (STI) integrated bio-behavioral surveillance surveys on men who have sex with men (MSM) as well as other key populations since 2005. Although HIV prevalence in the Vietnamese general population remains below 1%, it is expected to be much higher among MSM.Data on HIV prevalence and sexual and drug use behaviors were collected from MSM in Ho Chi Minh City (HCMC) in 2006 (n = 397), 2009 (n = 399) and 2013 (n = 350) using respondent-driven sampling. Eligible participants were males, aged ≥15 years who reported having manual, oral, or anal sexual activity with males in the past year and lived, worked or socialized in HCMC.HIV seroprevalence among MSM was 5.8% in 2006, 16.1% in 2009 and 12.1% in 2013 and prevalence of at least one STI (syphilis, gonorrhea and/or chlamydia infection) was 11.4% in 2006 and 15.6% in 2009 (no data for 2013). Significant, but small, increasing trends were found for MSM who reported ever testing and receiving results for HIV and for HIV prevalence. No significant changes for condom use, injecting and non-injecting drug use, or and receipt of free condoms were observed.Although a small percentage of MSM reported injecting drugs, HIV was positively associated with ever injecting drugs. Programs targeting MSM should include screening and treatment for injection drug use to most effectively control the HIV/AIDS epidemic among MSM in HCMC.