The team quantified the potential population impact of a prophylactic Helicobacter pylori vaccine, and reported their results in the December issue of Vaccine.
A mathematical model that compartmentalized the population according to age, infection status, and clinical state was developed.
A proportion of individuals were assumed to acquire infection and develop gastritis, duodenal ulcer (DU), chronic atrophic gastritis, and gastric cancer (GC).
The model was first simulated without vaccine intervention, to obtain estimates of H. pylori prevalence, and GC and DU incidences based on intrinsic dynamics.
The researchers then incorporated a prophylactic vaccine (80% efficacy, lifetime protection, 80% coverage), targeting all infants.
Vaccination programs were tested over unlimited, as well as limited, time-spans. Analyses were performed for the US, Japan, and a prototypical developing country.
In the US, the model predicted a decrease in H. pylori prevalence from 12.0% in 2010 to 4.2% in 2100 without intervention.
With 10 years of vaccination beginning in 2010, prevalence would decrease to 0.7% by year 2100.
| A continuous H. pylori vaccination program would be needed in developing countries.
| Vaccine |
In the same period, incidence of H. pylori-attributable GC would decrease from 4.5 to 0.4 per 100,000 with vaccine (compared to 1.3 per 100,000 without vaccine).
Incidence of H. pylori-attributable DU would decrease from 33.3 to 2.5 per 100,000 with vaccine (compared to 12.2 per 100,000 without vaccine).
In Japan, incidence of H. pylori-attributable GC would decrease from 17.6 to 1.0 per 100,000 after 10 years of vaccination (compared to 3.0 per 100,000 without vaccine).
In a prototypical developing country, after 10 years of vaccination, H. pylori-attributable GC would decrease from 31.8 to 22.5 per 100,000 by 2090, returning to the original level by mid-2100s.
The researchers found that, under continuous vaccination, it would decrease to 5.8 per 100,000 by 2100.
Author Marcia F. T. Rupnow, of Stanford University, California, said on behalf of her colleagues, "In the US and Japan, a 10-year vaccination program would confer almost the same reduction in H. pylori and associated diseases as a vaccination effort that extends beyond 10 years."
"In developing countries, a continuous vaccination effort would be required to eliminate the pathogen and its associated diseases," she concluded.