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Observational Study
. 2024 Nov 14;19(11):e0309355.
doi: 10.1371/journal.pone.0309355. eCollection 2024.

Prospective longitudinal study of men who have sex with men and transgender women to determine HIV incidence in two provinces in Thailand

Chawetsan Namwat  1 , Warong Leela-Apiradee  2 , Thawat Tiawilai  3 , Nicole Dear  4   5 , Tanyaporn Wansom  5   6 , Suchai Kitsiripornchai  6 , Nakorn Premsri  1 , Siriwat Akapirat  6 , Trevor A Crowell  4   5 , Leilani Francisco  4   5 , Qun Li  4   5 , Merlin L Robb  4   5 , Kirsten S Smith  7 , Elizabeth A Heger  8 , Mark M Fukuda  6 , Robert J O'Connell  7 , Supachai Rerks-Ngarm  1 , Sandhya Vasan  4   5 ; RV348M Study Group
Affiliations
Observational Study

Prospective longitudinal study of men who have sex with men and transgender women to determine HIV incidence in two provinces in Thailand

Chawetsan Namwat et al. PLoS One. .

Abstract

Background: In Thailand, HIV transmission is well characterized in large urban centers such as Bangkok and Chiang Mai but less so outside of these areas. The main purpose of this study was to assess HIV incidence and associated risk factors in Nakhon Ratchasima and Ratchaburi.

Methods: Participants assigned male sex at birth were enrolled in this prospective observational cohort study between November 2017 and July 2018. HIV and syphilis testing and sociobehavioral questionnaires were administered over 18 months. HIV incidence rates and 95% confidence intervals (CIs) were estimated using a Poisson distribution. Cox proportional hazards models were used to estimate unadjusted and adjusted hazard ratios (aHRs) and 95% CIs for associations between potential risk factors and HIV seroconversion.

Results: A total of 1003 participants were enrolled. Overall HIV incidence was 1.56 per 100 person-years (95% CI:1.02-2.44) and similar at both sites. In the fully adjusted model, sex with a sex worker in the past six months was associated with reduced risk of seroconversion (aHR:0.10, 95% CI:0.01-0.77). In the reduced adjusted model, receptive anal sex (aHR:3.40, 95% CI:1.32-8.74) and STI diagnosis in the past six months (aHR:3.58, 95% CI:1.19-10.76) were associated with seroconversion, while sex with a sex worker in the past six months was associated with reduced risk of seroconversion (aHR:0.11, 95% CI:0.02-0.67). Additionally, 56% reported interest in taking PrEP and 82% reported willingness to participate in a hypothetical future vaccine trial.

Conclusions: Recent receptive anal sex practices were associated with HIV acquisition in these populations, highlighting the continued need for interventions encouraging safer anal sex practices to reduce HIV incidence.

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Conflict of interest statement

NO authors have competing interests.

Figures

Fig 1
Fig 1. Visit adherence by site.
Visit adherence was calculated at each follow-up visit as the number of participants who completed the visit divided by the number of participants who were expected to complete the visit. The number expected to complete each visit was calculated as the number enrolled minus the number who seroconverted before that visit. P-values were calculated using proportion tests for each visit.
Fig 2
Fig 2. Kaplan Meier curves for probability of acquiring HIV.
Probability of Acquiring HIV by (A) Site, (B) Sex with a sex worker in the past six months, (C) Engaged in receptive anal sex in past six months, and (D) Been diagnosed with an STI in past 6 months.
Fig 3
Fig 3. Reasons for willingness or unwillingness to participate in a vaccine trial.
Participants were asked reasons for willingness or unwillingness to participate in an HIV vaccine trial from a predetermined set of responses; participants could select multiple reasons.
See this image and copyright information in PMC

References

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