What is the Prevnar Vaccine?
Prevnar is a pneumococcal conjugate vaccine that contains purified capsular polysaccharides from specific Streptococcus pneumoniae serotypes, each covalently linked to a non-toxic carrier protein (CRM197), designed to prevent invasive pneumococcal disease, pneumonia, and otitis media. 1
Vaccine Composition and Technology
- Prevnar vaccines contain no live or attenuated organisms—only purified polysaccharide antigens from pneumococcal capsules chemically conjugated to CRM197, a non-toxic variant of diphtheria toxin 2, 1
- The original Prevnar (PCV7) contained 7 serotypes, Prevnar 13 (PCV13) expanded coverage to 13 serotypes, and the newest Prevnar 20 (PCV20) covers 20 serotypes of S. pneumoniae 1, 3
- Each vaccine dose contains an aluminum phosphate adjuvant to enhance immune response 2, 1
How It Works: The Conjugate Advantage
- The protein conjugate induces a T-cell dependent immune response by stimulating T-helper cells, which creates immunologic memory and enables booster responses upon re-exposure 2, 4
- This mechanism is fundamentally different from polysaccharide vaccines (PPSV23), which rely on T-independent responses that fail in young children and do not create lasting memory 4
- Conjugate vaccines are effective even in infants as young as 6 weeks, whereas polysaccharide vaccines are ineffective in children under 2 years because they cannot mount adequate responses to T-independent antigens 4, 1
Clinical Indications
For Children:
- Active immunization for prevention of invasive disease caused by vaccine serotypes in individuals 6 weeks of age and older 1
- Prevention of otitis media caused by serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F in children 6 weeks through 5 years of age 1
- Recommended for all infants at ages 2,4,6, and 12-15 months 5
For Adults:
- Prevention of pneumonia and invasive disease caused by vaccine serotypes in individuals 18 years and older 1
- Particularly important for adults with immunocompromising conditions, functional or anatomic asplenia, CSF leaks, or cochlear implants 5
Unique Public Health Benefits
- Conjugate vaccines reduce nasopharyngeal carriage of pneumococci, creating herd immunity effects that protect unvaccinated individuals—an effect not seen with polysaccharide vaccines 2, 4
- The original PCV7 prevented 86% of bacteremia, 83% of meningitis, and 65% of otitis media cases among children under 6 years in the United States 5
Safety Profile
- Safe for immunocompromised patients, including those with HIV, sickle cell disease, functional asplenia, and those on immunosuppressive therapy 2
- No risk of vaccine-strain disease transmission since it contains no live organisms 2
- Generally well tolerated with an adverse event profile similar across all Prevnar formulations 1, 6
Critical Clinical Distinction
Never use polysaccharide vaccine (PPSV23) alone in children under 2 years—it is ineffective in this age group. 4 When both vaccines are indicated in older children with risk factors, always administer PCV before PPSV23 (at least 2 months apart) to optimize immune response 4