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Respondent-driven sampling (RDS) is widely used to sample populations with higher risk of HIV infection for whom no sampling frames exist. However, few studies have been done to assess the reliability of RDS in real world settings. We assessed the reliability of naïve RDS samples using five rounds of the National HIV Behavioral Surveillance – People Who Inject Drugs surveys in Newark, New Jersey from 2005 to 2018. Specifically, we compared the distributions of time-insensitive demographic characteristics in temporally adjacent RDS samples with Monte Carlo Two-Sample Kolmogorov-Smirnov Test with 100,000 replicates. The distributions of time-sensitive demographic characteristics were also compared as sensitivity analyses. The study showed that repeated RDS samples among people who inject drugs in the greater Newark area, New Jersey were reliable in most of time-insensitive demographics and recruitment homophily statistics. Sensitivity analyses of time-sensitive demographics also presented consistencies in most of temporally adjacent samples. In conclusion, RDS has the potential to provide reliable samples, but demographic characteristics of RDS samples may be easily biased by homophily. Future studies using RDS may need to pay more attention to potential homophily bias and consider necessary diagnostic procedures and sample adjustments. [ABSTRACT FROM AUTHOR]

• Oral cholera vaccine producers recommend to keep the vaccine vials at 2–8 °C. • So far oral cholera vaccine campaigns followed producers' recommendations. • In Lake Chilwa second vaccine dose was kept at room temperature for two weeks. • This study showed high short-term effectiveness after such vaccine campaign. • Results was comparable to campaigns that stored both vaccine doses at 2–8 °C. In response to a cholera outbreak among mobile, difficult-to-reach fishermen on Lake Chilwa, Malawi in 2016, a novel vaccine distribution strategy exploited the proven vaccine thermostability. Fishermen, while taking the first vaccine dose under supervision, received the second dose in a sealed bag, and were told to drink it two weeks later. This study assessed short-term vaccine protection of this strategy. Patients with diarrhoea admitted to health facilities around lake were interviewed and a stool sample collected for PCR testing. Vaccine effectiveness was assessed in a case-control test-negative design by comparing cases (PCR-positive for V. cholerae O1) and controls (patients with diarrhoea but PCR-negative) and with the screening method that compared the proportions of vaccinated among cholera cases versus the general fishermen population. Of 145 study participants, 120 were fishermen living on the lake. Vaccine effectiveness at three-months was 90.0% [95% CI: 38.8; 98.4] among fishermen and 83.3% [95% CI: 20.8; 96.5] among all participants in the case-control test-negative design, and 97.5% [95% CI: 90.9; 99.3] with the screening method. This strategy was effective in providing short-term protection in fishermen against cholera. Further research is needed to determine the adding value of the second dose and to identify the optimal vaccination strategies for different contexts. [ABSTRACT FROM AUTHOR]

Abstract Background Since special efforts are necessary to vaccinate people living far from fixed vaccination posts, decision makers are interested in knowing the economic value of such efforts. Methods Using our immunization geospatial information system platform and a measles compartment model, we quantified the health and economic value of a 2-dose measles immunization outreach strategy for children <24 months of age in Kenya who are geographically hard-to-reach (i.e., those living outside a specified catchment radius from fixed vaccination posts, which served as a proxy for access to services). Findings When geographically hard-to-reach children were not vaccinated, there were 1427 total measles cases from 2016 to 2020, resulting in $9.5 million ($3.1–$18.1 million) in direct medical costs and productivity losses and 7504 (3338–12,903) disability-adjusted life years (DALYs). The outreach strategy cost $76 ($23–$142)/DALY averted (compared to no outreach) when 25% of geographically hard-to-reach children received MCV1, $122 ($40-$226)/DALY averted when 50% received MCV1, and $274 ($123-$478)/DALY averted when 100% received MCV1. Conclusion Outreach vaccination among geographically hard-to-reach populations was highly cost-effective in a wide variety of scenarios, offering support for investment in an effective outreach vaccination strategy. [ABSTRACT FROM AUTHOR]

Existing methods to estimate the prevalence of chronic hepatitis C (HCV) in New York City (NYC) are limited in scope and fail to assess hard-to-reach subpopulations with highest risk such as injecting drug users (IDUs). To address these limitations, we employ a Bayesian multi-parameter evidence synthesis model to systematically combine multiple sources of data, account for bias in certain data sources, and provide unbiased HCV prevalence estimates with associated uncertainty. Our approach improves on previous estimates by explicitly accounting for injecting drug use and including data from high-risk subpopulations such as the incarcerated, and is more inclusive, utilizing ten NYC data sources. In addition, we derive two new equations to allow age at first injecting drug use data for former and current IDUs to be incorporated into the Bayesian evidence synthesis, a first for this type of model. Our estimated overall HCV prevalence as of 2012 among NYC adults aged 20–59 years is 2.78% (95% CI 2.61–2.94%), which represents between 124,900 and 140,000 chronic HCV cases. These estimates suggest that HCV prevalence in NYC is higher than previously indicated from household surveys (2.2%) and the surveillance system (2.37%), and that HCV transmission is increasing among young injecting adults in NYC. An ancillary benefit from our results is an estimate of current IDUs aged 20–59 in NYC: 0.58% or 27,600 individuals. [ABSTRACT FROM AUTHOR]

Summary The paper sets out to explore the possibility that citizen-led surveys provide a better coverage of populations and specifically of hard-to-reach poorer areas than the international standardized household surveys which are the basis for many of the estimates used in assessing progress toward meeting the MDGs and will be for the SDGs. This hypothesis is based on the argument that, the local volunteer enumerators of citizen-led surveys are likely to be more sensitive to the specificities of local population distribution and (recent) changes than those centrally trained; and may be more effective at reaching hard-to reach groups such as those nomadic groups and those in urban slums. To test the hypothesis, the results of UWEZO (meaning “capability”) surveys have been compared at a regional level with those of contemporaneous DHS surveys in Kenya, Tanzania, and Uganda for estimates of access to water and electricity. Overall, at national level, we find that UWEZO estimates for access to clean water were lower at a statistically significant level than those of DHS and these differences were statistically significant at the 0.01% level; in particular, the DHS values were much higher in regions where there are high concentrations of nomads and of urban slums, implying that the UWEZO surveys “catch” more poverty. The suggestion therefore is that citizen surveys such as UWEZO provide better, and more accurate, coverage of the poorest of the poor. Using the lowest estimate of the percentage “missing” in urban slums and extrapolating to all developing countries, there are an estimated 369 million missing from the sampling frames of standardized household surveys worldwide. This has important implications for the “Leave no one behind” appeal of the UN Secretary General and for the UN’s “Data Revolution”. Some suggestions are made about how to progress improved population estimates. [ABSTRACT FROM AUTHOR]

Background: The burden of sexually transmitted infections (STIs), such as syphilis, is higher in low-income countries, with serious consequences and profound impact on sexual and reproductive health and human immunodeficiency virus (HIV) spread. Syphilis prevalence tend to be higher among people who misuse drugs than in the general population.Objective: To assess syphilis and associated factors among polydrug users (PDU) in the city of Salvador, Northeast Brazil.Methods: A cross-sectional study was conducted in 10 Brazilian cities between September and November 2009 using Respondent Driven Sampling (RDS). Participants answered an Audio Computer-Assisted Self Interview (ACASI) and were rapid tested for HIV and syphilis. We performed multivariable regression models for correlates of syphilis on Stata 10.0. Estimates were weighted by the inverse size of the individual social network size and homophily.Results: Mean age was 29.3 years (range: 18-62), 74.0% were males, and 89.8% were non-white. Syphilis prevalence was 16.6%. Females (adjwOR:2.14; 95%CI:1.09-4.20), individuals over 29 years old (adjwOR:4.44; 95%CI:2.41-8.19), those who exchanged sex for money or drugs (adjwOR:3.51; 95%CI:1.84-6.71), "No/low" self-perceived risk of HIV infection (adjwOR:5.13; 95%CI:1.36-19.37), and having nine or less years of education (adjwOR:2.92; 95%CI:1.08-7.88) were associated with syphilis.Conclusion: One of the most pressing needs for syphilis prevention/control is the availability of rapid point-of-care diagnostic tests and treatment. Interventions should be tailored to PDU needs and their multiple burdens as shown in the present study, that may contribute to future studies aiming to better understand the relationships between drug use and syphilis. [ABSTRACT FROM AUTHOR]

Objective Report lessons learned in an RCT of Stop My Smoking (SMS) USA, a mHealth smoking cessation program for young adult smokers. Methods 164 18–24-year-olds were recruited nationally, online in 2011. Program evaluation data were provided at 12-week post-Quit Day. Results (1) Inviting participants to complete a brief text messaging survey and then asking them to complete a longer online survey resulted in the highest response rate (89%). (2) The positive tone of program messages was the most commonly noted program strength. (3) Suggested improvements included more social connectivity and additional assistance overcoming stressful situations. (4) Half of intervention participants moved through the program linearly and half went through various paths that reflected multiple relapses. Suggestions to use pharmacotherapy resulted in 22% of heavy smokers to utilize it. Conclusion Participant feedback provided concrete ways in which this and other young adult-focused interventions can improve messaging and program features to be even more salient. Practice implications Future young adult mHealth interventions could: Integrate models that are flexible to different “paths” of behavior change; address stressful life events directly and comprehensively; integrate proactive messaging that promotes pharmacotherapy options; and use text messaging as a gateway to longer online surveys. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To measure immunization coverage among children aged 12–23 months in Papua New Guinea (PNG) and to assess if and why there are differences between hard-to-reach and more accessible communities. Methods: WHO cluster sampling methodology was employed to measure immunization coverage in PNG''s four regions. Survey data were re-analyzed according to a local assessment of geographical accessibility indicated by census unit type: urban, rural and hard-to-reach. Census units were designated as hard-to-reach if they were five or more kilometres from a health centre. Findings: Nationwide coverage for most antigens falls below the national target of 80% although there are regional differences with Islands performing the best. Late doses are a major concern: just 4% were fully immunized with valid (“on time”) doses by 1 year of age. Coverage was lower in both rural and remote communities: at 6 months 48% of children from urban units had received three valid doses of DTP-3 but only 16% in rural areas and 13% in hard-to-reach communities. Reasons for failure to immunize varied: 21% of mothers said their child was not immunized because distance, travel conditions or cost of transportation prevented access to local health centres; 27% cited a lack of knowledge or misconceptions about immunization; while 29% believed it was because of an issue with the health system. Conclusions: Throughout PNG there is an urgent need to increase immunization coverage and to ensure that children are immunized on time according to the schedule. Both coverage and timeliness of doses are worse for children living in hard-to-reach and rural areas. Achieving national immunization targets requires improvements in health service delivery, including outreach, especially for remote and rural communities, as well as greater community education and social mobilisation in support of immunization services. [Copyright &y& Elsevier]