HIV Testing, Information Spillovers, and Peer Behavior



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This dissertation consists of two chapters. In the first chapter, I study the effect of HIV testing the risky behaviors of peer groups. Empirical studies to date offer mixed evidence on whether HIV testing prevents the spread of the disease. While most studies have focused on the effect of testing on the individual’s own behavior, I examine the effect of HIV testing on the peer network using a unique dataset of injecting drug users from the Ukraine. I find that individuals who update their beliefs about their HIV status—from negative to positive following testing—induce less risky behavior among peers. More specifically, the peers double their spending on needles in comparison to peers who do not experience a change in information. The more robust response documented here also points to needle sharing among drug users as a viable alternative to the more commonly studied condom use and risky sexual practices for gauging the effectiveness of HIV testing on changing beliefs and behaviors.

In the second chapter, I study the effect of HIV testing on sexual behavior among couples and singles. Previous studies examining the effects of HIV testing on sexual behaviour have showed limited behavioral response to the epidemic. I examine a possible explanation for this, namely, individuals can respond to HIV not only by engaging in safer sex, but may adjust the frequency of sexual contacts or stop having sex. I also study the effect of HIV testing on condom usage allowing for this possibility. Empirical results indicate that HIV testing increases condom usage among singles and it has no effect on condom usage among couples. At the same time there is no evidence that HIV testing affects the frequency of sexual acts among singles or couples.



HIV testing, Peers, Peer effects, Health economics, Peer Behavior, HIV