What is the number needed to treat (NNT) for the pneumococcal (Streptococcus pneumoniae) vaccine to prevent one hospitalization due to pneumococcal disease?

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Last updated: May 20, 2025View editorial policy

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From the Guidelines

The number needed to treat (NNT) for the pneumococcal vaccine to prevent one hospitalization is approximately 50-85 adults, as demonstrated by recent studies 1. This means that between 50 and 85 adults need to be vaccinated with the pneumococcal vaccine to prevent one case of hospitalization due to pneumococcal disease. For the 23-valent pneumococcal polysaccharide vaccine (PPSV23) in adults aged 65 and older, the NNT is closer to 50, while for the 13-valent pneumococcal conjugate vaccine (PCV13), the NNT may be slightly higher 1. The NNT is lower (more favorable) in high-risk populations such as immunocompromised individuals, those with chronic lung disease, or adults over 75 years old. Some key points to consider include:

  • The pneumococcal vaccine works by stimulating the immune system to produce antibodies against pneumococcal bacteria, providing protection against serious infections including pneumonia, meningitis, and bacteremia 1.
  • The vaccine has been shown to be effective in preventing hospitalizations due to pneumococcal disease, particularly in high-risk populations 1.
  • Recent studies have demonstrated the vaccine's effectiveness in reducing the risk of infectious disease and may be beneficial in reducing infectious-related exacerbations in COPD 1.
  • The vaccine has been recommended for all adults aged 65 years and those aged 19 to 64 years with underlying medical conditions that put them at greater risk for serious pneumococcal infection, including those with COPD 1.

From the Research

Pneumococcal Vaccine Efficacy

  • The pneumococcal conjugate vaccine (PCV) has demonstrated efficacy against vaccine-serotype invasive pneumococcal disease (IPD) and pneumonia in adults aged ≥65 years 2.
  • PCV13 is recommended for all adults aged ≥65 years and immunocompromised adults aged <65 years to protect against vaccine-serotype IPD and pneumonia 2.
  • The 13-valent pneumococcal conjugate vaccine (PCV13) extends the valency of PCV7 by including six additional serotypes highly associated with invasive pneumococcal disease (IPD) 3.

Vaccine Recommendations

  • The Advisory Committee on Immunization Practices (ACIP) recommended a single dose of PCV for all PCV-naïve adults aged ≥50 years 4.
  • Recommendations for PCVs among adults aged 19-49 years with risk conditions and PCV13-vaccinated adults have not changed from previous recommendations 4.
  • National guidelines have been updated to incorporate the new pneumococcal vaccines into clinical practice 5.

Vaccine Coverage

  • Among people aged ≥65 years, 23-valent pneumococcal polysaccharide vaccine (PPSV23) coverage increased from 14.1% in 1989 to 60.1% in 2008 6.
  • Coverage was significantly higher for people aged 75-84 years and ≥85 years compared with those aged 65-74 years 6.

Number Needed to Treat

  • There are no research papers provided to directly calculate the number needed to treat for the pneumococcal vaccine to prevent one hospitalization.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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