Pneumococcal Vaccines Ineffective at Reducing Hospitalizations and Deaths

Despite decades of public health campaigns promoting pneumococcal vaccination to prevent pneumonia and related deaths, new real-world evidence suggests the shots may not be delivering the expected benefits. A 2025 population-based cohort study of more than 2.2 million adults in Catalonia, Spain, published Oct. 21, 2025 in BMC Infectious Diseases, found that recipients of pneumococcal vaccines were more likely to be hospitalized for pneumonia—and, in some cases, more likely to die from pneumonia-related causes—than their unvaccinated peers. Instead of reducing risk, pneumococcal vaccination correlated with an increased likelihood of hospitalization and death from pneumonia.¹

The study found a statistically significant association between pneumococcal vaccination and higher pneumonia-related hospitalization and mortality rates. Adjustments for demographic and medical risk factors did not eliminate the association, suggesting both PCV13 and PPSV23 may contribute to unfavorable outcomes.¹

The authors of the study reported: “Receipt of PCV13 was associated with a greater risk of pneumococcal pneumonia (HR: 1.83; 95% CI: 1.49–2.24) and all-cause pneumonia (HR: 1.55; 95% CI: 1.42–1.70), while receipt of PPSV23 was also associated with increased risk (HR: 1.21 and 1.24, respectively).” They concluded that “pneumococcal vaccination did not prove effective… in preventing hospitalized pneumococcal pneumonia, all-cause pneumonia, or death from these causes.” Notably, even among the groups most vulnerable to pneumonia—older adults, immunocompromised patients, and those with chronic heart or lung disease—the vaccines showed no measurable benefit, undermining the rationale for maintaining current high-risk or universal adult recommendations.¹

Pneumococcal Vaccine Recommendations Rest on Outdated and Indirect Evidence

In the United States, the Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices (ACIP) currently recommends pneumococcal vaccination beginning in early childhood and continuing into adulthood. Infants and children under age five should receive a four-dose series of a pneumococcal conjugate vaccine—either PCV15 or PCV20—administered at two, four, six, and 12 to 15 months of age. For adults aged 50 and older who have not previously received a pneumococcal conjugate vaccine (or whose vaccination history is unknown), ACIP advises a single dose of PCV15, PCV20, or PCV21. If PCV15 is used, the agency recommends following it with a PPSV23 booster one year later—or as soon as eight weeks later for those with certain high-risk conditions.²

These recommendations remain in place despite the absence of any new randomized controlled trials in more than a decade. The authors point out that “Since the CAPITA RCT… no RCT has been published evaluating clinical efficacy/effectiveness of pneumococcal vaccines in adults,” raising concerns that current guidance rests on outdated or indirect evidence.¹

Although newer pneumococcal conjugate vaccines—PCV15, PCV20, and the recently introduced PCV21—have replaced PCV13 in adult immunization schedules, the underlying vaccine platform remains largely unchanged. As the study authors note, these newer products are “extended-valency” formulations that build directly on PCV13 by including “all of the same serotypes plus additional ones.”¹

They continue to rely on the same diphtheria-derived carrier protein (CRM197) and similar conjugation and adjuvant systems to stimulate immunity. In other words, the biological mechanism and manufacturing design remain the same—only the number of serotypes has expanded—raising questions about whether newer versions will perform any better than their predecessors. The authors emphasized that the effectiveness of these newer vaccines “must be re-evaluated in the coming years.”¹

“The new BMC Infectious Diseases findings therefore carry serious implications,” epidemiologist Nicolas Hulscher, MPH said in a Substack post analyzing the data. “Those who previously received PCV13 or PPSV23 may face the same elevated risks of pneumonia and death observed in this large-scale study, and these risks could plausibly persist—or even amplify—under the expanded PCV15, PCV20, and PCV21 formulations now in widespread use.”³

Landmark Study ‘Shattered Rationale’ for Current PCV Recommendations

Hulscher says that the study has “shattered the rationale for current pneumococcal conjugate vaccine (PCV) recommendations.” “Since its introduction in 2010, PCV13 has been administered to tens of millions of Americans, including nearly every child and most seniors, forming the backbone of the national pneumococcal vaccination program.” He concludes, “After more than three decades of use in adults and universal promotion in children, this evidence calls into question the entire foundation of pneumococcal vaccine policy and warrants immediate attention from public health authorities.”³

The study authors echo Hulscher’s concerns: “Our data raise serious concerns about effectiveness and public health impact of the adult antipneumococcal vaccination program in Catalonia at the time of the study.”¹

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