OBJECTIVES: Historic data suggest that most 1918 influenza pandemic-related deaths were due to pneumococcal disease (PD); preliminary evidence shows a similar pattern for the 2009 H1N1 influenza outbreak. Implementation of 13-valent pneumococcal conjugate vaccine (PCV13) national immunization programs would likely lessen the impact of a pandemic in Asia-Pacific populations that currently have low pneumococcal vaccination rates; our objective was to quantify this impact in Singapore and Hong Kong. METHODS: We used a decision-analytic model to assess the impact of PCV13 infant vaccination on PD incidence and mortality in an influenza pandemic in Singapore and Hong Kong versus no vaccination.  The model was estimated from published sources; both direct and indirect (herd) effects against PD were included. Effectiveness of PCV13 was extrapolated from observed US 7-valent PCV (PCV7) data, using assumptions on serotype prevalence in the pre-PCV7 era, and PCV13 protection against the 6 serotypes not in PCV7. Country-specific data were used where available; where unavailable, US data were used. To simulate acceleration of PD transmission in a flu pandemic, we calibrated to 1918 estimates of country-specific incidence and mortality, adjusting mortality for the advent of antibiotics.  PD incidence and mortality, and total PD-related health-care costs were evaluated over a 1-year horizon.  Results are reported in local 2008 currency. RESULTS: Preliminary results of the model indicate that in a pandemic of 1918 severity, PCV13 vaccination would prevent 3,300 cases of hospitalized pneumococcal pneumonia and 320 deaths in Singapore, and save SGD1.53 million in health-care costs (net of vaccination).  In Hong Kong, PCV13 would prevent 8,200 cases of hospitalized pneumonia (all-cause), and 2,200 pneumonia deaths, respectively; PCV13 would save HKD250 million in medical costs.  CONCLUSIONS: In an influenza pandemic affecting the Asia-Pacific region, infant vaccination with PCV13 would likely be highly effective in reducing pandemic-related deaths, PD cases and associated costs.