Population-based Seroprevalence Surveys Research Articles

Estimates of HIV Incidence, Prevalence, and Mortality in China 2018.

A thorough and precise comprehension understanding of the HIV epidemic is crucial for effective HIV prevention and control. This study aimed to update the estimates of the overall HIV burden in China in 2018 and to assess the trends of HIV prevalence, incidence, and mortality from 1985 to 2018. The Estimation and Projection Package (EPP)/Spectrum software was utilized for estimation, a method highly recommended by UNAIDS. Data were collected from more than 1800 HIV sentinel surveillance sites, population-based seroprevalence surveys, and HIV screening of antenatal clinics and pre-marital medical check-ups across the country. Assumptions about age and sex were used to adapt the parameters of disease progression, including CD4 progression rates and mortality rates for individuals on and off antiretroviral therapy (ART). Joinpoint (version 4.7.0.0) was used to analyze the trends of prevalence, incidence, mortality, and fatality rates from 1985 to 2018. In 2018, the total number of people living with HIV (PLWH) adults in China was estimated to be 1.23 million, corresponding to approximately 106.5/100 000 in the country. A total of 71.8% of adult PLWH were men. Over half of PLWH (58.6%) were infected through heterosexual contact, about one-third (30.2%) through male-to-male transmission, 9.0% through IDU, and 2.3% due to former plasma donation. HIV incidence in adults reached its first small peak in 1992 with 52 400 new infections (95% confidence interval: 2700-920 000). After a brief period of rapid decline between 1992 and 1994, the annual number of new infections among adults increased again and remained relatively stable at 81 000 (95% uncertainty interval [UI]: 60 000-105 000) in 2018. In recent years, the number of new infections through blood donation has been eliminated, and the number of infections through injecting drug use has been kept low. Sexual contact became the predominant transmission route, while casual sexual contact became increasingly common. Overall, HIV mortality has been steadily increasing and has recently begun to decline during the period of 2012-2018. The number of deaths from HIV/AIDS in 2018 was approximately 35 000 (95% UI: 30 000-41 000). The number of estimated PLWH in China has exceeded one million, due to the ongoing occurrence of new infections and longer survival rates. HIV transmission through blood products has been eradicated. Casual sex has become a significant mode of transmission. It is recommended to enhance the implementation of strategies and measures for sexual communication in the general population and to bolster multidisciplinary research.

Prevalence of long COVID symptoms in Haryana, India: a cross-sectional follow-up study

Emerging research indicates growing concern over long COVID globally, although there have been limited studies that estimate population burden. We aimed to estimate the burden of long COVID in three districts of Haryana, India, using an opportunity to link a seroprevalence study to follow-up survey of symptoms associated with long COVID. We used a population-based seroprevalence survey for COVID-19 conducted in September 2021 across Haryana, India. Adults from three purposively selected districts (Rohtak, Gurugram, and Jhajjar) were eligible to participate; 2205 of 3213 consented to participate in a survey on health status. Trained investigators administered a structured questionnaire that included demographic characteristics, self-reported symptoms of illness in the last six months before the survey, mental health, and history of COVID-19. Unadjusted regression estimates indicated positive correlations between symptomatic complaints and COVID-19 exposure, suggesting lingering effects of COVID-19 in this population. The overall physical morbidity index was higher among those who tested positive for COVID-19, as was the incidence of new cases. However, both morbidity and incidence became statistically insignificant after adjustment for multiple comparisons. Cough emerged as the only statistically significant individual persistent symptom. Sex-stratified analyses indicated significant estimates only for physical morbidity in women. This study is one of the first from India that uses a large population-based sample to examine longer term repercussions of COVID infections. The burden of long COVID should primarily be addressed in clinical settings, where specialised treatment for individual cases continues to evolve. Our analyses also provide insight into the size and nature of studies required to assess the population-level burden of long COVID. This paper was produced under the auspices of the Lancet COVID 19 Commission India Task Force, which was supported financially by the Reliance Foundation. The Lancet COVID 19 Commission was set up in July 2020 and submitted its final report by October 2022. This report by the India Task Force was prepared during the same period.

Poliovirus antibodies following two rounds of campaigns with a type 2 novel oral poliovirus vaccine in Liberia: a clustered, population-based seroprevalence survey

Novel oral poliovirus vaccine type 2 (nOPV2) was administered in Liberia in response to an outbreak of circulating vaccine-derived poliovirus type 2 (cVDPV2) in 2021. We conducted a serological survey of polio antibodies after two national campaigns with nOPV2. This clustered, cross-sectional, population-based seroprevalence survey was conducted in children aged 0-59 months, more than 4 weeks after the second nOPV2 vaccination round. We used a clustered sampling method in four geographical regions of Liberia, followed by a simple random sampling of households. One eligible child was randomly selected per household. Dried blood spot specimens were taken and vaccination history was recorded. The antibody titres against all three poliovirus serotypes were assessed using standard microneutralisation assays done at the US Centers for Disease Control and Prevention in Atlanta, GA, USA. Analysable data were obtained from 436 (87%) of 500 enrolled participants. Of these, 371 (85%) children were reported via parental recall to have received two nOPV2 doses, 43 (10%) received one dose, and 22 (5%) received no doses. The seroprevalence against type 2 poliovirus was 38·3% (95% CI 33·7-43·0; 167 of 436 participants). No significant difference was observed between type 2 seroprevalence in children aged 6 months or older who were reported to have received two doses of nOPV2 (42·1%, 95% CI 36·8-47·5; 144 of 342), one dose (28·0%, 12·1-49·4; seven of 25), or no doses (37·5%, 8·5-75·5; three of eight; p=0·39). The seroprevalence against type 1 was 59·6% (54·9-64·3; 260 of 436), and the seroprevalence against type 3 was 53·0% (48·2-57·7; 231 of 436). Unexpectedly, the data showed low type 2 seroprevalence after two reported doses of nOPV2. This finding is probably affected by the lower oral poliovirus vaccine immunogenicity previously demonstrated in resource-limited settings, with high prevalence of chronic intestinal infections in children and other factors discussed herein. Our results provide the first assessment of nOPV2 performance in outbreak response in the African region. WHO and Rotary International.

Immunity Against SARS-CoV-2 in the German Population.

Early during the SARS-CoV-2 pandemic, national population-based seroprevalence surveys were conducted in some countries; however, this was not done in Germany. In particular, no seroprevalence surveys were planned for the summer of 2022. In the context of the IMMUNEBRIDGE project, the GUIDE study was carried out to estimate seroprevalence on the national and regional levels. To obtain an overview of the population-wide immunity against SARS-CoV-2 among adults in Germany that would be as statistically robust as possible, serological tests were carried out using self-sampling dried blood spot cards in conjunction with surveys, one by telephone and one online. Blood samples were analyzed for the presence of antibodies to the S and N antigens of SARS-CoV-2. Among the 15 932 participants, antibodies to the S antigen were detected in 95.7%, and to the N antigen in 44.4%. In the higher-risk age groups of persons aged 65 and above and persons aged 80 and above, anti-S antibodies were found in 97,4% and 98.8%, respectively. Distinct regional differences in the distribution of anti-S and anti-N antibodies emerged. Immunity gaps were found both regionally and in particular subgroups of the population. High anti-N antibody levels were especially common in eastern German states, and high anti-S antibody levels in western German states. These findings indicate that a large percentage of the adult German population has formed antibodies against the SARS-CoV-2 virus. This will markedly lower the probability of an overburdening of the health care system by hospitalization and high occupancy of intensive care units due to future SARS-CoV-2 waves, depending on the viral characteristics of then prevailing variants.

Seroprevalence of anti-SARS-CoV-2 antibodies in Colombia, 2020: A population-based study

BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to cause very high morbidity and mortality throughout Latin American countries. However, few population-based seroprevalence surveys have been conducted to quantify attack rates and characterize drivers of transmission.MethodsWe conducted a population-based cross-sectional study to assess the seroprevalence of antibodies against SARS-CoV-2 in ten cities in Colombia between September and December 2020. The study involved multi-stage cluster sampling at each city. Participants provided a serum sample and answered a demographic and risk factor questionnaire. Prior infection by SARS-CoV-2 was ascertained using the "SARS-CoV-2 Total (COV2T) Advia Centaur - Siemens" chemiluminescence assay.FindingsA total of 17863 participants from 7320 households participated in the study. Seroprevalence varied substantially between cities, ranging from 26% (95%CI 23–29 %) in Medellín to 68% (95%CI 62–74 %) in Guapi. There were no differences in seroprevalence by sex, but seropositivity was higher in certain ethnic groups. There was substantial heterogeneity in seroprevalence within cities, driven to a large extent by a strong association between socioeconomic stratum and seropositivity.InterpretationColombia has been one of the Latin American countries most affected by the COVID-19 pandemic. This study documented very high attack rates in several Colombian cities by the end of 2020 and identified key drivers of heterogeneities including ethnicity and socioeconomic stratum. Few studies of seroprevalence of SARS-CoV-2 have been conducted in Latin America, and therefore this study contributes to the fundamental understanding of the pandemic in the region.FundingThe study was sponsored by, Ministerio de Ciencia y Tecnología e Innovación –CT361/2020, Ministerio de Salud y Protección Social, Fundación Universitaria del Norte, Imperial College of London, Universidad Nacional de Colombia (Sede Medellín), Universidad de Córdoba, California University, Unidad Nacional de Gestión del Riesgo, Centro de Atención y Diagnóstico de Enfermedades Infecciosas -CDI-, Centro Internacional de Entrenamiento e Investigaciones Médicas -CIDEIM-, Departamento Administrativo Nacional de Estadística - DANE, Fondo Nacional de Turismo -FONTUR-, Secretarías de Salud Departamentales, Distritales y Municipales and Instituto Nacional de Salud.

Prevalence of SARS-Cov-2 antibodies and living conditions: the French national random population-based EPICOV cohort

BackgroundWe aimed to estimate the seroprevalence of SARS-CoV-2 infection in France and to identify the populations most exposed during the first epidemic wave.MethodsRandom selection of individuals aged 15 years or over, from the national tax register (96% coverage). Socio-economic data, migration history, and living conditions were collected via self-computer-assisted-web or computer-assisted-telephone interviews. Home self-sampling was performed for a random subsample, to detect IgG antibodies against spike protein (Euroimmun), and neutralizing antibodies with in-house assays, in dried blood spots (DBS).ResultsThe questionnaire was completed by 134,391 participants from May 2nd to June 2st, 2020, including 17,441 eligible for DBS 12,114 of whom were tested. ELISA-S seroprevalence was 4.5% [95% CI 3.9–5.0] overall, reaching up to 10% in the two most affected areas. High-density residences, larger household size, having reported a suspected COVID-19 case in the household, working in healthcare, being of intermediate age and non-daily tobacco smoking were independently associated with seropositivity, whereas living with children or adolescents did not remain associated after adjustment for household size. Adjustment for both residential density and household size accounted for much of the higher seroprevalence in immigrants born outside Europe, twice that in French natives in univariate analysis.ConclusionThe EPICOV cohort is one of the largest national representative population-based seroprevalence surveys for COVID-19. It shows the major role of contextual living conditions in the initial spread of COVID-19 in France, during which the availability of masks and virological tests was limited.

The Study to Investigate COVID-19 Infection in People Living in Ireland (SCOPI): A seroprevalence study, June to July 2020.

BackgroundRobust data on SARS-CoV-2 population seroprevalence supplement surveillance data in providing evidence for public health action.AimTo conduct a SARS-CoV-2 population-based seroprevalence survey in Ireland.MethodsUsing a cross-sectional study design, we selected population samples from individuals aged 12–69 years in counties Dublin and Sligo using the Health Service Executive Primary Care Reimbursement Service database as a sampling frame. Samples were selected with probability proportional to the general population age–sex distribution, and by simple random sampling within age–sex strata. Antibodies to SARS-CoV-2 were detected using the Abbott Architect SARS-CoV-2 IgG Assay and confirmed using the Wantai Assay. We estimated the population SARS-CoV-2 seroprevalence weighted for age, sex and geographic area.ResultsParticipation rates were 30% (913/3,043) and 44% (820/1,863) in Dublin and Sligo. Thirty-three specimens had detectable SARS-CoV-2 antibodies (1.9%). We estimated weighted seroprevalences of 3.12% (95% confidence interval (CI): 2.05–4.53) and 0.58% (95% CI: 0.18–1.38) for Dublin and Sligo, and 1.69% (95% CI: 1.13–2.41) nationally. This equates to an estimated 59,482 (95% CI: 39,772–85,176) people aged 12–69 years nationally having had infection with SARS-CoV-2, 3.0 (95% CI: 2.0–4.3) times higher than confirmed notifications. Ten participants reported a previous laboratory-confirmed SARS-CoV-2 -infection; eight of these were antibody-positive. Twenty-five antibody-positive participants had not reported previous laboratory-confirmed infection.ConclusionThe majority of people in Ireland are unlikely to have been infected with SARS-CoV-2 by June–July 2020. Non-pharmaceutical public health measures remained key pending widespread availability of vaccination, and effective treatments.

Seroprevalence of SARS-CoV-2-specific IgG antibodies in Kashmir, India, 7 months after the first reported local COVID-19 case: results of a population-based seroprevalence survey from October to November 2020

ObjectivesWe designed a population-based survey in Kashmir to estimate the seroprevalence of SARS-CoV-2-specific IgG antibodies in the general population aged 18 years and above.SettingThe survey was conducted among 110 villages...

Prevalence and undiagnosed fraction of hepatitis C infection in 2018 in Spain: results from a national population-based survey.

A national strategy against hepatitis C virus (HCV) was implemented in Spain in 2015 with the aim of reducing associated morbidity and mortality. In order to improve our understanding of the epidemiology of HCV, we analysed the prevalence of HCV antibodies and active infection overall and by age and sex in the general population aged 20-80 years. We also aimed to report the undiagnosed fraction. A national population-based seroprevalence survey was conducted in 2017-2018. A representative sample from the general population was selected using two-stage sampling. The prevalence of total HCV antibodies and of HCV RNA was calculated using inverse probability weighting based on bootstrapping. Overall, we approached 17496 persons; 9103 agreed to participate and met the eligibility criteria and 7675 were aged 20-80. We obtained a prevalence of HCV antibodies of 0.85% [95% confidence interval (CI): 0.64-1.08%] and of active infection of 0.22% (95% CI: 0.12-0.32%). The prevalence of active HCV infection was highest in men aged 50-59 (0.86%; 95% CI: 0.28-1.57%) and in men aged 60-69 years (0.72%; 95% CI: 0.27-1.28%). Prevalence was below 0.20% in the remaining age groups. The undiagnosed fraction for active HCV infection was 29.4%. This study shows that prevalence of HCV in the general population in Spain is low and reflects the impact of scaling up treatment with direct acting antivirals, together with other prevention strategies, from 2015 onwards. The data reported can guide subsequent public health actions.

A Bayesian estimate of the early COVID-19 infection fatality ratio in Brazil based on a random seroprevalence survey

Background:A number of estimates of the infection fatality ratio (IFR) of SARS-CoV-2 in different countries have been published. In Brazil, the fragile political situation, together with socioeconomic and ethnic diversity, could result in substantially different IFR estimates.Methods:We infer the IFR in Brazil in 2020 by combining three datasets. We compute the prevalence via the population-based seroprevalence survey, EPICOVID19-BR. For the fatalities we obtain the absolute number using the public Painel Coronavírus dataset and the age-relative number using the public SIVEP-Gripe dataset. The time delay between the development of antibodies and subsequent fatality is estimated via the SIVEP-Gripe dataset. We obtain the IFR for each survey stage and 27 federal states. We include the effect of fading IgG antibody levels by marginalizing over the test detectability time window.Results:We infer a country-wide average IFR (maximum posterior and 95% CI) of 1.03% (0.88–1.22%) and age-specific IFRs of 0.032% (0.023–0.041%) [< 30 years], 0.22% (0.18–0.27%) [30–49 years], 1.2% (1.0–1.5%) [50–69 years], and 3.0% (2.4–3.9%) [≥ 70 years]. We find that the fatality ratio in the country increased significantly at the end of June 2020, likely due to the increased strain on the health system.Conclusions: Our IFR estimate is based on data and does not rely on extrapolating models. This estimate sets a baseline value with which future medications and treatment protocols may be confronted.

Hepatitis C virus infection and risk of liver-related and non-liver-related deaths: a population-based cohort study in Naples, southern Italy

BackgroundHepatitis C virus (HCV) infection represents a global health issue with severe implications on morbidity and mortality. This study aimed to evaluate the impact of HCV infection on all-cause, liver-related, and non-liver-related mortality in a population living in an area with a high prevalence of HCV infection before the advent of Direct-Acting Antiviral (DAA) therapies, and to identify factors associated with cause-specific mortality among HCV-infected individuals.MethodsWe conducted a cohort study on 4492 individuals enrolled between 2003 and 2006 in a population-based seroprevalence survey on viral hepatitis infections in the province of Naples, southern Italy. Study participants provided serum for antibodies to HCV (anti-HCV) and HCV RNA testing. Information on vital status to December 2017 and cause of death were retrieved through record-linkage with the mortality database. Hazard ratios (HRs) for cause-specific mortality and 95% confidence intervals (CIs) were estimated using Fine-Grey regression models.ResultsOut of 626 deceased people, 20 (3.2%) died from non-natural causes, 56 (8.9%) from liver-related conditions, 550 (87.9%) from non-liver-related causes. Anti-HCV positive people were at higher risk of death from all causes (HR = 1.38, 95% CI: 1.12–1.70) and liver-related causes (HR = 5.90, 95% CI: 3.00–11.59) than anti-HCV negative ones. Individuals with chronic HCV infection reported an elevated risk of death due to liver-related conditions (HR = 6.61, 95% CI: 3.29–13.27) and to any cause (HR = 1.51, 95% CI: 1.18–1.94). The death risk of anti-HCV seropositive people with negative HCV RNA was similar to that of anti-HCV seronegative ones. Among anti-HCV positive people, liver-related mortality was associated with a high FIB-4 index score (HR = 39.96, 95% CI: 4.73–337.54).ConclusionsThese findings show the detrimental impact of HCV infection on all-cause mortality and, particularly, liver-related mortality. This effect emerged among individuals with chronic infection while those with cleared infection had the same risk of uninfected ones. These results underline the need to identify through screening all people with chronic HCV infection notably in areas with a high prevalence of HCV infection, and promptly provide them with DAAs treatment to achieve progressive HCV elimination and reduce HCV-related mortality.

Assessment of initial SARS-CoV-2 seroprevalence in the most affected districts in the municipality of São Paulo, Brazil

BackgroundSão Paulo city has been one of the regions most affected by the COVID-19 pandemic in Brazil. Frequent asymptomatic and oligosymptomatic infections and poor access to diagnostic tests make serosurveys crucial to monitor the magnitude of the epidemic and to inform public health policies, such as vaccination plans. ObjectivesTo estimate, early in the epidemic, the seroprevalence of antibodies to SARS-CoV-2 in adults living in the six most affected districts in São Paulo city, and to assess potential associated risk factors. MethodsThis was a cross-sectional population-based survey of 1,152 households randomly selected from 72 census tracts. During the period May 4–12, 2020, 463 participants completed a questionnaire on sociodemographic characteristics and history of symptoms in the past two weeks, and provided a blood sample. Prevalence of SARS-CoV-2 antibodies was the outcome of interest and was estimated based on results of two immunoassays, Maglumi SARS-CoV-2 chemiluminescence assay Immunoglobulin (Ig) M (IgM) and IgG, and Roche electrochemiluminescence assay total Ig. Serum samples reactive to either assay were considered positive. ResultsWeighted overall seroprevalence was 6% (95%CI 3.9–8.3%). No association was observed between seropositivity and sex, age group or education level. Participants who reported black and brown skin color showed a 2.7 fold higher prevalence than people with white skin (p = 0.007). Among the 30 seropositive individuals, 14 (46.6%) reported no COVID-19 compatible symptoms in the past two weeks. ConclusionThis study represents the first assessment of SARS-CoV-2 seroprevalence in the city of São Paulo and 6% is the baseline estimate of a series of population-based seroprevalence surveys. Serological screening using sound serological assays is the key tool to monitoring temporal and geographic changes in the spread of the virus through an important epicenter of the COVID-19 pandemic in Brazil. Ultimately, it may inform prevention and control efforts.

Prevalence of SARS-CoV-2 antibodies in Denmark: nationwide, population-based seroepidemiological study

Seroprevalence studies have proven an important tool to monitor the progression of the coronavirus disease 2019 (COVID-19) pandemic. We present results of consecutive population-based seroprevalence surveys performed in Denmark in 2020. In spring, late summer and autumn/winter of 2020, invitation letters including a questionnaire covering symptoms were sent to representative samples of the population above 12 years and to parents of children below 18 years in the sample. Blood samples were analysed for total Ig and seroprevalence estimates per population segment were calculated and compared to other surveillance parameters. Based on 34 081 participants (participation rate 33%), seroprevalence estimates increased from 1.2% (95%CI: 0.3–1.9%) in May to 4.1% (95%CI: 3.1–4.9%) in December 2020. Seroprevalence estimates were roughly three times higher in those aged 12–29 years compared to 65 + and higher in metropolitan municipalities. By December 2020, 1.5% of the population had tested positive by RT-PCR. Infected individuals in older age groups were hospitalised several fold more often than in younger. Amongst seropositives, loss of taste/smell were the more specific symptoms, 32–56% did not report any symptoms. In more than half of seroconverted families, we did not see evidence of transmission between generations. Seroprevalence increased during 2020; adolescents were primarily infected in the autumn/winter. Denmark has a high per capita test rate; roughly one undiagnosed infection of SARS-CoV-2 were estimated to occur for each diagnosed case. Approximately half were asymptomatically infected. The epidemic appears to have progressed relatively modestly during 2020 in Denmark.

Characterization of Immune Responses to SARS-CoV-2 and Other Human Pathogenic Coronaviruses Using a Multiplex Bead-Based Immunoassay.

Serological assays that simultaneously detect antibodies to multiple targets of SARS-CoV-2 and to other structurally related coronaviruses provide a holistic picture of antibody response patterns. Well-validated multiplex immunoassays are scarce. Here, we evaluated the performance of an 11-plex serological assay capable of detecting antibodies directed to four antigenic targets of SARS-CoV-2 and to S1 proteins of other human pathogenic coronaviruses. We used 620 well-characterized sera (n = 458 seropositive and n = 110 seronegative for SARS-CoV-2 in the pre-SARS-CoV-2 era and n = 52 seronegative for SARS-CoV-2 in the era of SARS-CoV-2) as positive and negative standards. We calculated the sensitivity, specificity, as well as positive and negative predictive values, including a 95% confidence interval. The difference in mean fluorescence intensity (95% CI) was used to assess a potential cross-reaction between antibodies to SARS-CoV-2 and the other coronaviruses. The sensitivity (95% CI) of detecting anti-SARS-CoV-2 antibodies to four antigenic targets ranged from 83.4% (76.7–86.7) to 93.7% (91.0–95.7) and the specificity from 98.2% (93.6–99.8) to 100% (96.7–100). We observed no obvious cross-reaction between anti-SARS-CoV-2 antibodies and antibodies to the other coronaviruses except for SARS-CoV-1. The high sensitivity and specificity warrant a reliable utilization of the assay in population-based seroprevalence surveys or vaccine efficacy studies.

Seroprevalence surveys in sub-Saharan Africa: what do they tell us?

Seroprevalence surveys in sub-Saharan Africa: what do they tell us?

Seroprevalence of Anti-Sars-Cov-2 Antibodies in Colombia, 2020: A Population-Based Study

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to cause very high morbidity and mortality throughout Latin American countries. However, few population-based seroprevalence surveys have been conducted to quantify attack rates and characterize drivers of transmission.Methods: We conducted a population-based cross-sectional study to assess the seroprevalence of antibodies against SARS-CoV-2 in ten cities in Colombia between September and December, 2020. The study involved multi-stage cluster sampling at each city. Participants provided a serum sample and answered a demographic and risk factor questionnaire. Prior infection by SARS-CoV-2 was ascertained using the "SARS-CoV-2 Total (COV2T) Advia Centaur - Siemens" chemiluminescence assay.Findings: A total of 17863 participants from 7075 households participated in the study. Seroprevalence varied substantially between cities, ranging from 21% (95%CI 16-25%) in Medellín to 78% (95%CI 65-91%) in Guapi. There were no differences in seroprevalence by sex, but seropositivity was lower in adults 60 years or older and higher in certain ethnic groups. There was substantial heterogeneity in seroprevalence within cities, driven to a large extent by a strong association between socio-economic stratum and seropositivity.Interpretation: Colombia has been one of the Latin American countries most affected by the COVID-19 pandemic. This study documented very high attack rates in several Colombian cities by the end of 2020 and identified key drivers of heterogeneities including ethnicity and socio-economic stratum. Few studies of seroprevalence of SARS-CoV-2 have been conducted in Latin America, and therefore this study contributes to the fundamental understanding of the pandemic in the region.

A Bayesian Estimate of the COVID-19 Infection Fatality Ratio in Brazil Based on a Random Seroprevalence Survey

Background: The COVID-19 pandemic continues to spread fast through Brazil after almost a year since the first fatality. Brazil, in addition to a fragile political situation, has a very socioeconomically and ethnically diverse population for which estimates of the infection fatality ratio (IFR) of SARS-CoV-2 relative to other countries may not be accurate. It is then important to estimate the IFR of SARS-CoV-2 for the Brazilian federal states as well as for Brazil as a whole.Methods: We compute the prevalence via the population-based seroprevalence survey EPICOVID19-BR. For the fatalities we obtain the absolute number using the public Painel Coronavírus dataset and the age-relative number using the public SIVEP-Gripe dataset. The time delay between the development of antibodies and subsequent fatality is estimated via the SIVEP-Gripe dataset. We obtain the IFR via Bayesian inference for each survey stage and 27 federal states. We include the effect of fading IgG antibody levels by marginalizing over the time after contagion at which the test gives a negative result with a flat prior on the interval [40,80] days.Findings: We infer a country-wide average IFR (maximum posterior and 95% CI) of 0.97% (0.82-1.14%) and age-specific IFR: 0.028% (0.024-0.036%) [Interpretation: Our IFR estimate is the most accurate to date for Brazil and one of the most detailed and careful estimates globally. It is based on data and does not rely on extrapolating models, and Bayesian inference is rigorously adopted. This estimate sets a baseline value with which future medications and treatment protocols may be confronted, especially with the rise of recent SARS-CoV-2 variants and the beginning of mass vaccination campaigns. The high IFR values found and its age-dependence generate actionable results.Funding: No funding was granted specifically for this project.Declaration of Interests: The authors declare no competing interests.

The impact of hepatitis B vaccination program in central Vietnam; evaluation by population-based, cross-sectional seroprevalence survey of HBsAg

Background: Vietnam is considered hyperendemic for hepatitis B and universal immunization for hepatitis B among infants has been implemented since 2003. To implement better disease control policies, effective impact evaluation of the vaccination program is warranted. Methods and materials: We conducted a stratified, multistage, cluster sampling survey of hepatitis B surface antigen (HBsAg) positivity among people aged 1–39 years old. Participants were randomly selected from the 4 provinces (Khanh Hoa, Ninh Thuan, Binh Dinh, Quang Ngai) in the central area of Vietnam via probability proportionate to size sampling. A face-to-face questionnaires and HBsAg rapid tests were administrated. Results: A total of 2078 participants were included into the study. The seroprevalence of HBsAg by age group for every 5years old was estimated as shown on the table below.Tabled 1agenHBsAg(+)95%CI1–42661.50%0.32–2.985–93663.01%1.25–4.7610–142981.01%0.00–2.1515–192493.61%1.28–5.9520–2416710.18%5.55–14.8125–292227.21%3.78–10.6430–3425211.11%7.20–15.0235–392589.30%5.73–12.87 Open table in a new tab In Vietnam, hepatitis vaccine was introduced in 1997 and was expanded nationwide in 2002. A birth dose was added to the immunization schedule in 2003. The decline in the prevalence of HBsAg in younger age groups may be attributed to the immunization program. However, the administrative birth dose coverage of Hepatitis B vaccine became temporally low after media reports of adverse events following immunization in 2007. High prevalence of HBsAg of HBsAg between the age of 5 and 9 in this area may be due to the low coverage of birth dose. Conclusion: Population based seroprevalence survey is able to provide valuable information to assess the effectiveness of previous vaccination and formulate future immunization policy. The survey with rapid field test is feasible and affordable way which can be applied in resource limited settings.

The role of drug resistance in poor viral suppression in rural South Africa: findings from a population-based study

BackgroundUnderstanding factors driving virological failure, including the contribution of HIV drug resistance mutations (DRM), is critical to ensuring HIV treatment remains effective. We examine the contribution of drug resistance mutations for low viral suppression in HIV-positive participants in a population-based sero-prevalence survey in rural South Africa.MethodsWe conducted HIV drug resistance genotyping and ART analyte testing on dried blood spots (DBS) from HIV-positive adults participating in a 2014 survey in North West Province. Among those with virologic failure (> 5000 copies/mL), we describe frequency of DRM to protease inhibitors (PI), nucleoside reverse transcriptase inhibitors (NRTI), and non-nucleoside reverse transcriptase inhibitors (NNRTI), report association of resistance with antiretroviral therapy (ART) status, and assess resistance to first and second line therapy. Analyses are weighted to account for sampling design.ResultsOverall 170 DBS samples were assayed for viral load and ART analytes; 78.4% of men and 50.0% of women had evidence of virologic failure and were assessed for drug resistance, with successful sequencing of 76/107 samples. We found ≥1 DRM in 22% of participants; 47% were from samples with detectable analyte (efavirenz, nevirapine or lopinavir). Of those with DRM and detectable analyte, 60% showed high–level resistance and reduced predicted virologic response to ≥1 NRTI/NNRTI typically used in first and second-line regimens.ConclusionsDRM and predicted reduced susceptibility to first and second-line regimens were common among adults with ART exposure in a rural South African population-based sample. Results underscore the importance of ongoing virologic monitoring, regimen optimization and adherence counseling to optimize durable virologic suppression.

Global, regional, and national incidence, prevalence, and mortality of HIV, 1980–2017, and forecasts to 2030, for 195 countries and territories: a systematic analysis for the Global Burden of Diseases, Injuries, and Risk Factors Study 2017

SummaryBackgroundUnderstanding the patterns of HIV/AIDS epidemics is crucial to tracking and monitoring the progress of prevention and control efforts in countries. We provide a comprehensive assessment of the levels and trends of HIV/AIDS incidence, prevalence, mortality, and coverage of antiretroviral therapy (ART) for 1980–2017 and forecast these estimates to 2030 for 195 countries and territories.MethodsWe determined a modelling strategy for each country on the basis of the availability and quality of data. For countries and territories with data from population-based seroprevalence surveys or antenatal care clinics, we estimated prevalence and incidence using an open-source version of the Estimation and Projection Package—a natural history model originally developed by the UNAIDS Reference Group on Estimates, Modelling, and Projections. For countries with cause-specific vital registration data, we corrected data for garbage coding (ie, deaths coded to an intermediate, immediate, or poorly defined cause) and HIV misclassification. We developed a process of cohort incidence bias adjustment to use information on survival and deaths recorded in vital registration to back-calculate HIV incidence. For countries without any representative data on HIV, we produced incidence estimates by pulling information from observed bias in the geographical region. We used a re-coded version of the Spectrum model (a cohort component model that uses rates of disease progression and HIV mortality on and off ART) to produce age-sex-specific incidence, prevalence, and mortality, and treatment coverage results for all countries, and forecast these measures to 2030 using Spectrum with inputs that were extended on the basis of past trends in treatment scale-up and new infections.FindingsGlobal HIV mortality peaked in 2006 with 1·95 million deaths (95% uncertainty interval 1·87–2·04) and has since decreased to 0·95 million deaths (0·91–1·01) in 2017. New cases of HIV globally peaked in 1999 (3·16 million, 2·79–3·67) and since then have gradually decreased to 1·94 million (1·63–2·29) in 2017. These trends, along with ART scale-up, have globally resulted in increased prevalence, with 36·8 million (34·8–39·2) people living with HIV in 2017. Prevalence of HIV was highest in southern sub-Saharan Africa in 2017, and countries in the region had ART coverage ranging from 65·7% in Lesotho to 85·7% in eSwatini. Our forecasts showed that 54 countries will meet the UNAIDS target of 81% ART coverage by 2020 and 12 countries are on track to meet 90% ART coverage by 2030. Forecasted results estimate that few countries will meet the UNAIDS 2020 and 2030 mortality and incidence targets.InterpretationDespite progress in reducing HIV-related mortality over the past decade, slow decreases in incidence, combined with the current context of stagnated funding for related interventions, mean that many countries are not on track to reach the 2020 and 2030 global targets for reduction in incidence and mortality. With a growing population of people living with HIV, it will continue to be a major threat to public health for years to come. The pace of progress needs to be hastened by continuing to expand access to ART and increasing investments in proven HIV prevention initiatives that can be scaled up to have population-level impact.FundingBill & Melinda Gates Foundation, National Institute of Mental Health of the US National Institutes of Health (NIH), and the National Institute on Aging of the NIH.