Prevnar 13 (PCV13) is a pneumococcal conjugate vaccine that protects against 13 strains of the bacterium Streptococcus pneumoniae, a leading cause of pneumonia, meningitis, and bloodstream infections. It covers serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F. Originally developed for infants and young children, the vaccine played a central role in dramatically reducing serious pneumococcal disease in the United States over the past two decades.
What Prevnar 13 Protects Against
Streptococcus pneumoniae bacteria can live harmlessly in the nose and throat, but when they spread to the lungs, bloodstream, or the lining of the brain, they cause what’s called invasive pneumococcal disease (IPD). In young children and older adults, IPD can be life-threatening. Before routine childhood vaccination began in the late 1990s with an earlier version of the vaccine, the U.S. recorded roughly 15,700 cases of IPD in children each year. By 2019, that number had dropped 91%, to about 1,380 cases, thanks largely to the introduction of pneumococcal conjugate vaccines.
The 13 serotypes in Prevnar 13 were chosen because they were responsible for the majority of severe pneumococcal infections at the time the vaccine was developed. Some of these strains, particularly 19A, had become increasingly resistant to antibiotics, making vaccination even more important as a first line of defense.
How the Vaccine Works
Prevnar 13 is a conjugate vaccine, which means each of the 13 bacterial sugar coatings (polysaccharides) is chemically linked to a carrier protein. This design is important because the immune systems of infants and young children don’t respond well to polysaccharides alone. By attaching the sugar to a protein, the vaccine triggers a stronger, longer-lasting immune response that produces memory cells capable of recognizing and fighting the bacteria if they’re encountered later.
This conjugate approach is what separates vaccines like Prevnar 13 from older polysaccharide-only vaccines, which work in adults but are ineffective in children under two. The protein-linked design also helps reduce the number of people who carry the bacteria in their nose and throat, which lowers transmission to others in the community.
Who Gets It and When
The CDC recommends routine pneumococcal vaccination for all children younger than 5. The standard schedule is a four-dose series given at 2 months, 4 months, 6 months, and between 12 and 15 months of age. This timing aligns with other routine childhood vaccinations, so it’s typically administered during the same well-child visits.
For adults, the pneumococcal vaccine landscape has shifted. Newer vaccines, PCV15 and PCV20 (Prevnar 20), now cover additional serotypes and have largely replaced Prevnar 13 in current adult recommendations. PCV20, for example, covers all 13 serotypes in Prevnar 13 plus seven more. Adults who previously received Prevnar 13 may still need a follow-up dose of a broader vaccine depending on their age and health conditions. Your provider can determine what’s needed based on your vaccination history.
Common Side Effects
Like most vaccines, Prevnar 13 can cause mild, short-lived reactions. The most common side effects in infants and young children include soreness, redness, or swelling at the injection site, along with fussiness, drowsiness, and mild fever. These reactions typically appear within a day or two and resolve on their own. In adults, injection-site pain, fatigue, headache, and muscle aches are the most frequently reported effects.
Severe allergic reactions are rare. The vaccine should not be given to anyone who has had a serious allergic reaction to a previous dose of any pneumococcal conjugate vaccine or to any of its components.
Prevnar 13 vs. Newer Vaccines
Prevnar 13 was approved in 2010 as an upgrade to Prevnar 7, which covered only seven serotypes. It remained the standard pneumococcal conjugate vaccine for over a decade. In 2021 and 2022, the FDA approved two newer options: PCV15 (covering 15 serotypes) and PCV20 (covering 20 serotypes). Both are now recommended for routine use in children and adults.
For children starting their vaccine series today, the CDC recommends either PCV15 or PCV20. For adults aged 65 and older, or younger adults with certain risk factors like chronic heart or lung disease, diabetes, or a weakened immune system, PCV20 is the preferred single-dose option. If PCV15 is given instead, it’s followed by a dose of an older polysaccharide vaccine to broaden coverage.
Prevnar 13 itself is still FDA-approved and may still be used in some settings, but it’s no longer the first-line recommendation for most people. If you or your child received Prevnar 13 in the past, that protection still counts, and your provider can advise whether additional doses of a newer vaccine are appropriate.