‘Stop using PPSV23’: expert urges NIP reform as Prevenar 20 emerges as only proven option

Fundamental questions have been raised about the effectiveness of the current National Immunization Program (NIP) for pneumococcal vaccines.

At the “Pfizer Press University” event hosted by Pfizer Korea, Professor Kim Dong-hyun of Inje University College of Medicine said that the 23-valent pneumococcal polysaccharide vaccine (PPSV23) now faces clear limitations. He argued for shifting the vaccination approach to focus on the protein-conjugated vaccine (PCV).

Professor Kim Dong-hyun of Inje University College of Medicine

PPSV23 shows reduced antibody response with repeated doses

Professor Kim pointed out that PPSV23 has immunological drawbacks: repeated doses in older adults lead to “hyporesponsiveness,” reducing antibody responses.

He explained that after initial PPSV23 vaccination in a 65-year-old, antibodies are made, but the plasma cells are short-lived, so subsequent doses fail to trigger a strong response.

“This is the structural limitation of polysaccharide vaccines,” Professor Kim said.

In the United States, sequential PPSV23 vaccination is no longer in the basic recommendations; instead, the system has been simplified to focus mainly on the protein-conjugated vaccine alone, Kim explained.

“I believe PPSV23 is not an immunologically reliable vaccine. For older adults, I think it's better not to get vaccinated at all,” he said.

Kim added that while pediatric NIP-generated herd immunity has reduced some adult infections, direct vaccination of older adults remains necessary due to epidemiological limitations.

‘Prevenar 20 is the only vaccine with proven efficacy, real-world effectiveness’

Professor Kim said Prevenar 20 (PCV20) stands out as the only vaccine with proven efficacy in studies and real-world effectiveness so far.

He noted, “Efficacy reflects trial results; effectiveness measures real-world infection reduction. Among pneumococcal vaccines in Korea, real-world data are available only for Prevenar 20.”

Prevenar has over 20 years of clinical and infectious-disease prevention experience, evolving from 7-, 13-, and 20-valent formulations. Kim noted that this legacy, plus real-world effectiveness data, gives Prevenar 20 the current advantage.

“To date, Prevenar is the only vaccine to have reduced invasive pneumococcal disease (IPD). It is crucial that this vaccine has proven experience in lowering infection rates, not merely addressing serotype expansion,” Kim said.

21-valent protein-conjugated vaccine proves efficacy, but its effectiveness remains uncertain

Professor Kim noted that while the 21-valent protein-conjugated vaccine (Capvaxive) introduced in Korea by MSD shows meaningful efficacy, real-world data are still lacking. “I believe the 21-valent vaccine is meaningful. However, there is almost no real-world data currently available. It is difficult to change policy based solely on modeling results,” Kim said.

Citing a U.K. modeling study published this year as an example, he noted that it received manufacturer support but has limitations, as it did not reflect changes in population structure, vaccination schedules, or post-pandemic serotype shifts.

Kim said, “Currently, no evidence shows the 21-valent vaccine is superior to Prevenar 20. Real-world data may shift recommendations, but for now, Prevenar 20 is standard.”

Pneumococcal infections rise ninefold amid heavy burden on older adults

Pfizer Korea also released a report showing a nearly ninefold increase in pneumococcal pneumonia cases in Korea, from 1,063 in 2021 to 10,191 in 2024, based on Health Insurance Review and Assessment Service data. Of these cases, 51.9 percent were infants under five, and the remaining cases were mostly in adults over 50.

Pneumonia is the third leading cause of death in Korea. In 2024, about 24 percent of pneumonia patients were aged 50 or older. Pneumococcus, the main cause of bacterial pneumonia, accounts for 27–69 percent of these cases and has a fatality rate of up to 60 percent in older adults.

Kim also referenced a domestic study on invasive pneumococcal infections in adults conducted by the Korea Disease Control and Prevention Agency from 2018 to 2021. The 20 serotypes in Prevenar 20 accounted for approximately 51 percent of all isolated strains, and serotypes 19F and 23F showed multidrug resistance.

Kim concluded, “Vaccine efficacy is about actual prevention, not just serotype coverage. Prevenar 20 is the only vaccine proven to cover key domestic serotypes and demonstrate clinical efficacy.”