Random network models to predict the long term impact of HPV vaccination on genital warts

Abstract

HPV vaccine induces a herd immunity effect in genital warts when a large number of the population is vaccinated. That aspect should be taken into account when devising new vaccine strategies, like vaccination at older ages or male vaccination. Therefore it is important to develop mathematical models with good predictive capacities. We devised a sexual contact network that was calibrated to simulate the Spanish epidemiology of different HPV genotypes. Through this model we simulated the scenario that occurred in Australia in 2007, where 12-13 year-old girls where vaccinated with a three-dose schedule of a vaccine containing genotypes 6 and 11, that protect against genital warts, and also a catch-up program in women up to 26 years of age. Vaccine coverage were 73% in girls with three doses and with coverage rates decreasing with age until 52% for 20 − 26 year-olds. A fast 59% reduction in the genital warts diagnoses occurred in the model in the first years after the start of the program, similar to what was described in the literature.

Uncertainty and sensitivity of the sexual behavior changes to the current human papillomavirus vaccination campaign in Spain

“…Here, we have revisited a random network model for the transmission and control of HPV infections in Spain. We have previously shown that this model is more realistic than standard classic approaches and, in particular, it predicts the fast decline in genital warts in Australia only 2 years after the beginning of the vaccination campaign 10 . This happens because the computational network model is able to describe the herd immunity effect of the HPV vaccination programs more accurately than the classic models.…”

“…An example of a small LSP network can be seen in Figure 4. More technical details for building the sexual contact network are described in previous publications 10,20 …”

“…This type of herd immunity due to the vaccination and the network structure is not considered in the classic models because of the assumption of the homogeneous mixing hypothesis. The presented example illustrates why these classic models are unable to explain situations as those happened in Australia, 8,9 meanwhile, others, based on sexual partners network, can 10 …”

“…In Díez‐Domingo et al, 10 we developed an HPV transmission dynamics model on a lifetime sexual partner's (LSP) network that uses individual contacts to monitor the evolution of the HPV infections, including features as the number of men who have sex with men (MSM), the number of LSP of each individual, and the frequency of the intercourses; this allows us to provide a more detailed and realistic approach than the classic models. This computational random network model has a large number of nodes to study the HPV infections and the effects of the nine‐valent vaccine on the short and long terms.…”

On the Elimination of Infections Related to Oncogenic Human Papillomavirus: An Approach Using a Computational Network Model

“…We previously developed an HPV transmission dynamics model on a lifetime sexual partners (LSP) network that uses individual contacts to monitor the evolution of HPV infections; this allows a more detailed and realistic approach than traditional continuous models [ 15 ]. This model was able to reproduce the initial results of the Australian vaccination campaign in terms of the rapid decline in the incidence of genital warts even after just two years of vaccination in girls [ 16 ].…”