Cost-utility analysis on the inclusion of pneumococcal vaccines in the national immunization program for older adults in the Philippines – Evidence from a middle-income country in Asia

Pneumonia is a relentless threat to older adults, a respiratory infection that can turn a routine cold into a life-threatening crisis. Among the many bacteria that cause this illness, Streptococcus pneumoniae is a particularly common culprit, responsible for severe cases of pneumonia, meningitis, and bloodstream infections. As people age, their immune systems become less effective at fighting off these invaders, making vaccination a critical line of defense. For decades, health officials have relied on a specific type of vaccine, known as a polysaccharide vaccine, to protect the elderly. It works by training the body to recognize the bacteria's outer shell. However, newer vaccines, called conjugate vaccines, have emerged. These are designed to trigger a stronger, longer-lasting immune response and can also reduce the amount of bacteria living in the nose and throat, potentially stopping the spread of disease to others. The question facing health planners in many countries is whether the added biological benefits of these newer, more expensive vaccines justify the extra cost, or if the older, simpler vaccine remains the most practical choice for a nation's public health budget.

In the Philippines, where pneumonia consistently ranks among the top causes of illness and death, researchers set out to answer this question for adults aged sixty and older. They built a detailed computer simulation to project what would happen over a fifteen-year period if the country adopted different vaccination strategies. The team compared four scenarios: doing nothing, giving only the older polysaccharide vaccine, or using a sequential approach where an older adult receives a newer conjugate vaccine followed by the older one. The researchers fed their model with real-world data on how often the disease strikes, how much it costs to treat patients in hospitals, and how long people live with or without the disease. They also accounted for the fact that vaccine protection fades over time, with the older vaccine losing its strength more quickly than the newer types. The goal was to determine which strategy offered the best balance of health benefits and financial cost for the country's healthcare system.

The simulation revealed a clear and somewhat surprising winner. When the researchers compared the costs and health outcomes, the strategy of using only the older polysaccharide vaccine emerged as the most efficient choice. This single-dose approach cost significantly less than the sequential strategies involving the newer conjugate vaccines. While the sequential strategies generated slightly higher or equal health gains in terms of quality-adjusted life years, these marginal benefits were far too small to justify their much higher price tags. Consequently, the older vaccine alone was found to be "dominant" over the more complex schedules; it was cheaper to administer and offered a far better overall value for the population than the alternative plans, which were deemed too expensive for the additional health they provided.

The study also looked at the financial impact on the national budget over five years. Even when accounting for the cost of buying the vaccines, storing them, and managing the logistics of delivery, the plan to use only the older vaccine actually saved money compared to doing nothing at all. This was because the money saved by preventing expensive hospitalizations for pneumonia and meningitis outweighed the cost of the shots. In contrast, the plans that included the newer conjugate vaccines were projected to cost the healthcare system billions of pesos more than the older vaccine alone, without providing enough additional health benefits to make that extra spending worthwhile. The researchers ran their model thousands of times with slightly different assumptions to test the strength of their findings, and in nearly every scenario, the older vaccine remained the most cost-effective option.

Despite these strong results, the authors are careful to note that their conclusions are based on the best data currently available, which has some gaps. The Philippines lacks a comprehensive national system for tracking exactly how many people get sick with specific types of pneumococcal bacteria, so the researchers had to rely on estimates and data from other countries. They also used a static model, which means their simulation did not account for how widespread vaccination might change the types of bacteria circulating in the community over time, a factor that could theoretically favor the newer vaccines. Furthermore, the study did not include the broader economic benefits of keeping older adults healthy, such as the savings from reduced caregiver burden or lost work time. Nevertheless, within the limits of the data they could access, the evidence points to a straightforward path forward.

The study concludes that for the Philippines, sticking with the current strategy of using the older polysaccharide vaccine for adults over sixty is the most prudent economic decision. While the newer conjugate vaccines offer biological advantages, the current price difference is too high to justify their use in a national program at this time. The researchers suggest that the country should focus on improving childhood vaccination rates, which helps protect the entire population, and on strengthening disease surveillance to better understand the local landscape of bacterial infections. Until more local data becomes available or the cost of the newer vaccines drops significantly, the older, single-dose vaccine remains the most reliable tool for protecting the nation's elderly from the heavy burden of pneumococcal disease.