Purpose: In prior influenza pandemics, pneumococcal complications of influenza have caused substantial morbidity and mortality. The usefulness and cost-effectiveness of pneumococcal polysaccharide vaccine (PPV) for healthcare workers (HCW) during an influenza pandemic is unknown.
Method: We used a Markov model to estimate the cost-effectiveness of PPV use in HCW compared to nonuse during an influenza pandemic. Age-specific incidence data on invasive pneumococcal disease (IPD) from the CDC were incorporated into the model, assuming that IPD occurred at twice the usual rate during the year of pandemic influenza in HCW (average age 45 years); both the IPD rate multiplier and average HCW age were varied widely in sensitivity analyses. Model time horizon was 15 years, taking a societal perspective and discounting costs and benefits at 3%/year. We obtained IPD costs from the National Inpatient Sample and utilities from the medical literature; an expert panel estimated PPV effectiveness. We assumed that: pneumococcal disease transmission from HCW to patient did not occur, heightened IPD risk occurred for only 1 year, and PPV did not prevent noninvasive pneumonia, all of which potentially bias against PPV.
Result: In the base case analysis, PPV prevented 39.1% of IPD cases and deaths in HCW, saving 0.00083 QALY (about 0.3 days) at a cost of $5.33, or $6207 per QALY gained compared to no vaccination. If heightened IPD risk related to pandemic influenza lasts 2 years, PPV costs $3302/QALY. Results are sensitive to HCW age, with incremental cost-effectiveness ratios rising to >$100,000/QALY at ages <29 under base case assumptions; however costs/QALY gained remain <$100,000 for HCW < 30 years old if IPD rates during the pandemic year are ≥ 4.2 times those seen during non-pandemic years. Pandemic-based PPV is cost saving in HCW aged ≥50 under base case assumptions. In a probabilistic sensitivity analysis, vaccinating all HCW is favored >74% of the time if the acceptability threshold is ≥$20,000/QALY and in >94% with thresholds ≥$50,000.
Conclusion: Vaccinating all healthcare workers to protect against pneumococcal disease during a pandemic influenza outbreak is likely to be economically reasonable in an analysis biased against vaccination. Vaccinating healthcare workers aged ≤30 may be more expensive, while vaccinating those ≥50 appears to be cost saving.
Candidate for the Lee B. Lusted Student Prize Competition