Background: Public health departments must allocate annual funds for disease prevention. With infectious diseases, complex dynamics related to the interplay of interventions, behavior, and disease transmission complicate these decisions. Rather than relying on a single prevention activity, combinations of multiple interventions over time may be optimal. Recent observational studies have suggested that outer membrane vesicle serogroup B meningococcal vaccine may also be approximately 40% effective against gonorrhea acquisition, and modeling studies suggest that vaccination could lead to beneficial population level benefits. In this paper, we calculate the dynamic optimal mixture of vaccination and screening interventions for population level gonorrhea control.
Methods: We modelled the transmission of gonorrhea in a heterosexual population of 100,000 individuals over 10 years, starting with an equilibrium prevalence of 1% in the absence of either intervention. Baseline transmission dynamics were determined by behavioral and biological factors parameterized from existing literature. Each year, patients could be vaccinated or enrolled in a quarterly screening program until an annual budget constraint was reached. A recently developed numerical method was used to compute the optimal combination of vaccination and screening by sex and enrollment modality (i.e., background screening versus symptomatic STI clinic visits) over the 10-year study period in order to minimize gonorrhea incidence. We estimated costs of enrollment and participation in the vaccination and/or screening programs and set the baseline budget for all gonorrhea prevention activities at $300,000. We summarize the averted infections and antibiotics spared.
Results: Under the baseline scenario, vaccinating only males averted the most infections. Over the 10-year study period, >8,100 cases of gonorrhea were averted ($370 per case averted). This was consistent across sensitivity analyses, except for two scenarios (decreasing screening cost; decreasing vaccine protection duration) that resulted in a combination of vaccination and screening, with female screening predominantly replacing male vaccination after year 6. Under a scenario without vaccination (only screening was available), ~3,500 fewer infections were averted and ~1,500 more courses of antibiotics were administered.
Conclusion: Male vaccination was the predominant control in most scenarios. A currently available vaccine, though modestly effective, may be preferable to frequent testing for the control of gonorrhea.
