The population impact of herpes simplex virus type 2 (HSV-2) vaccination on the incidence of HSV-2, HIV and genital ulcer disease in South Africa: a mathematical modelling studyResearch in context
Jack Stone,
Katharine Jane Looker,
Romain Silhol,
Katherine Mary Elizabeth Turner,
Richard Hayes,
Jenny Coetzee,
Stefan Baral,
Sheree Schwartz,
Philippe Mayaud,
Sami Gottlieb,
Marie-Claude Boily,
Peter Vickerman
Affiliations
Jack Stone
Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK; Corresponding author. Population Health Sciences, Bristol Medical School, University of Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, United Kingdom.
Katharine Jane Looker
Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
Romain Silhol
MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
Katherine Mary Elizabeth Turner
Bristol Veterinary School, University of Bristol, Bristol, UK
Richard Hayes
Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, UK
Jenny Coetzee
Perinatal HIV Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; South African Medical Research Council, Cape Town, South Africa
Stefan Baral
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
Sheree Schwartz
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
Philippe Mayaud
Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
Sami Gottlieb
Department of Sexual and Reproductive Health and Research, World Health Organization, Geneva, Switzerland
Marie-Claude Boily
MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
Peter Vickerman
Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK; NIHR Health Protection Research Unit in Behavioural Science and Evaluation at University of Bristol, Bristol, UK
Summary: Background: Evidence suggests HSV-2 infection increases HIV acquisition risk and HIV/HSV-2 coinfection increases transmission risk of both infections. We analysed the potential impact of HSV-2 vaccination in South Africa, a high HIV/HSV-2 prevalence setting. Methods: We adapted a dynamic HIV transmission model for South Africa to incorporate HSV-2, including synergistic effects with HIV, to evaluate the impact of: (i) cohort vaccination of 9-year-olds with a prophylactic vaccine that reduces HSV-2 susceptibility; (ii) vaccination of symptomatically HSV-2-infected individuals with a therapeutic vaccine that reduces HSV shedding. Findings: An 80% efficacious prophylactic vaccine offering lifetime protection with 80% uptake could reduce HSV-2 and HIV incidence by 84.1% (95% Credibility Interval: 81.2–86.0) and 65.4% (56.5–71.6) after 40 years, respectively. This reduces to 57.4% (53.6–60.7) and 42.1% (34.1–48.1) if efficacy is 50%, 56.1% (53.4–58.3) and 41.5% (34.2–46.9) if uptake is 40%, and 29.4% (26.0–31.9) and 24.4% (19.0–28.7) if protection lasts 10 years. An 80% efficacious therapeutic vaccine offering lifetime protection with 40% coverage among symptomatic individuals could reduce HSV-2 and HIV incidence by 29.6% (21.8–40.9) and 26.4% (18.5–23.2) after 40 years, respectively. This reduces to 18.8% (13.7–26.4) and 16.9% (11.7–25.3) if efficacy is 50%, 9.7% (7.0–14.0) and 8.6% (5.8–13.4) if coverage is 20%, and 5.4% (3.8–8.0) and 5.5% (3.7–8.6) if protection lasts 2 years. Interpretation: Prophylactic and therapeutic vaccines offer promising approaches for reducing HSV-2 burden and could have important impact on HIV in South Africa and other high prevalence settings. Funding: WHO, NIAID.
