Fig. 3.

Effect of vaccination age and coverage on vaccine impact without immune-interactions. (A) and (B) Vaccination-only impact as the percent reduction in total incidence relative to pre-vaccination levels over two time periods post-vaccination (first 15 years in A, and first 25 years in B). (C) and (D) Impact of vaccination coupled with an initial catch-up campaign over two post-vaccination time periods (first 15 years in C and first 25 years in D). In all subplots, there is a clear age-dependence in vaccine impact, introduced from the unequal vaccine efficacies between naive and seropositive individuals. The catch-up campaign has a strong effect in the short-term impact of the vaccine, which dictates its more positive outcome after 25 years. However, the 25 year period may include a strong rebound effect in incidence (see main text and Fig. 2). The target age group for catch-up was between 10 and 50 years.