Ensaios clínicos com vacinas para o vírus do herpes genital foram capazes de imunizar mulheres com história prévia negativa para a doença. O impacto epidemiológico desse tipo de vacina sobre a população feminina é tema de artigo publicado no periódico Sexually Transmitted Infections, que mostra também que a imunização feminina universal, apesar de não ser completamente eficaz em evitar a doença, pode impedir com sucesso a disseminação assintomática do vírus do herpes.
Sexually Transmitted Infections
Sex Transm Infect 2004;80:24-29
© 2004 BMJ Publishing Group Ltd
The potential epidemiological impact of a genital herpes vaccine for women G P Garnett1, G Dubin3, M Slaoui2 and T Darcis2
1 Department of Infectious Disease Epidemiology, Imperial College of Science, Technology and Medicine, St Mary’s Campus, Norfolk Place, London, UK
2 GlaxoSmithKline Biologicals, Rixensart, Belgium
3 GlaxoSmithKline, King of Prussia, PA, USA
Professor Geoffrey Garnett
Department of Infectious Disease Epidemiology, Imperial College of Science, Technology and Medicine, St Mary’s Campus, Norfolk Place, London, UK; email@example.com
Background: In two phase III vaccine trials immunisation of women previously uninfected by herpes simplex virus provided protection against genital herpes disease. In deciding policy, an evaluation of the epidemiological impact of the partial protection provided by the vaccine should be considered.
Methods: A sex and sexual activity stratified deterministic differential and partial differential equation model of the natural history of herpes simplex virus type 2 (HSV-2) and the impact of vaccination is developed and analysed. To explore the role of vaccination, the pattern of viral shedding and the transmission of infection during sexual acts within sexual partnerships are described.
Results: Using literature derived estimates of parameter values and assuming efficacy in only 40% of women the impact of the vaccine depends on assumptions made about its action. The vaccine has a limited impact if it only prevents disease but a more substantial impact if it reduces asymptomatic viral shedding, which it could do indirectly by preventing infection or directly by modifying the biology of the infection. Concern over the implications of a vaccine that prevents disease but has no impact on viral shedding was addressed in a worst case scenario. Here there is a modest increase in the incidence of infection in both men and women but an increase in disease prevalence in men alone, since the virus directly protects some women from disease.
Conclusions: Results suggest that a herpes vaccine should be used universally and that a vaccine that only protects HSV-1-/2- women can paradoxically have a significant epidemiological impact, the scale of which depends upon changes in patterns of viral shedding.