An Immunization Strategy for Hidden Populations

Saran Chen,Xin Lu

doi:10.1038/s41598-017-03379-4

Abstract

Hidden populations, such as injecting drug users (IDUs), sex workers (SWs) and men who have sex with men (MSM), are considered at high risk of contracting and transmitting infectious diseases such as AIDS, gonorrhea, syphilis etc. However, public health interventions to such groups are prohibited due to strong privacy concerns and lack of global information, which is a necessity for traditional strategies such as targeted immunization and acquaintance immunization. In this study, we introduce an innovative intervention strategy to be used in combination with a sampling approach that is widely used for hidden populations, Respondent-driven Sampling (RDS). The RDS strategy is implemented in two steps: First, RDS is used to estimate the average degree (personal network size) and degree distribution of the target population with sample data. Second, a cut-off threshold is calculated and used to screen the respondents to be immunized. Simulations on model networks and real-world networks reveal that the efficiency of the RDS strategy is close to that of the targeted strategy. As the new strategy can be implemented with the RDS sampling process, it provides a cost-efficient and feasible approach for disease intervention and control for hidden populations.

Highlights

Hidden or hard-to-reach populations, including injecting drug users (IDUs), sex workers (SWs) and men who have sex with men (MSM), are generally considered at higher risk of contracting and transmitting infectious diseases such as AIDS, gonorrhea, syphilis etc.[1,2,3], developing efficient intervention and immunization strategies for hidden populations is crucial to prevent and control the spread of these sexual transmitted diseases
To study the efficiency of the respondent-driven sampling (RDS) strategy, we focused on the critical immunized fraction fc, which is the minimum fraction of the population required to be immunized for the eradication of epidemics, i.e., the infection’s prevalence ρf = 0
We propose an immunization strategy based on the RDS process, which is a sampling methodology currently widely adopted and applied in the study of hidden populations worldwide

Summary

Introduction

Hidden or hard-to-reach populations, including IDUs, SWs and MSM, are generally considered at higher risk of contracting and transmitting infectious diseases such as AIDS, gonorrhea, syphilis etc.[1,2,3], developing efficient intervention and immunization strategies for hidden populations is crucial to prevent and control the spread of these sexual transmitted diseases. The hard-to-access property of hidden populations makes these traditional strategies not applicable as there is no list of a sampling frame from which influential spreaders or initial random individuals could be selected to design immunization or intervention strategies. We can see that current intervention and immunization strategy are all limited by the nature of hidden populations and lack an approach to access and target the key individuals. To overcome these limitations, in this study, we develop an efficient strategy, which is based on a sampling approach currently used widely for hidden populations, called respondent-driven sampling (RDS). This information can be used for correction and unbiased estimation in statistical inferences[27, 28]

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