Prevnar 20 is a pneumococcal conjugate vaccine that protects against 20 strains of the bacterium Streptococcus pneumoniae, a leading cause of pneumonia, bloodstream infections, meningitis, and ear infections. It’s approved for anyone from 6 weeks of age through adulthood, making it one of the broadest pneumococcal vaccines available.
What Prevnar 20 Protects Against
Streptococcus pneumoniae bacteria come in many different types, identified by the sugary coating (capsule) on their surface. Prevnar 20 targets 20 of the most common and dangerous types: 1, 3, 4, 5, 6A, 6B, 7F, 8, 9V, 10A, 11A, 12F, 14, 15B, 18C, 19A, 19F, 22F, 23F, and 33F.
These strains collectively cause a large share of serious pneumococcal disease. The vaccine is FDA-approved for three specific uses:
- Invasive disease prevention (bloodstream infections, meningitis) in anyone 6 weeks and older
- Pneumonia prevention in adults 18 and older
- Ear infection prevention in children 6 weeks through 5 years, covering 7 of the 20 strains most responsible for middle ear infections
How It Differs From Prevnar 13
Prevnar 20 is built on the same platform as its predecessor, Prevnar 13. It keeps all 13 original strains and adds seven more: serotypes 8, 10A, 11A, 12F, 15B, 22F, and 33F. These seven additional strains were chosen because they account for a significant portion of pneumococcal disease not covered by the older vaccine. For most people, Prevnar 20 has replaced Prevnar 13 as the preferred option.
How a Conjugate Vaccine Works
The word “conjugate” in the vaccine’s name refers to its design. Pneumococcal bacteria have a polysaccharide (sugar) shell that young children’s immune systems and some older adults’ immune systems struggle to recognize on their own. In a conjugate vaccine, pieces of that sugar shell are chemically linked to a carrier protein, a nontoxic form of diphtheria protein called CRM197.
This pairing changes how your immune system processes the vaccine. When immune cells encounter the sugar-protein combination, they can recruit a type of immune cell called helper T cells. That T cell involvement triggers a stronger, longer-lasting response: your body produces higher-quality antibodies, learns to recognize the bacteria faster on repeat exposure, and builds lasting immune memory. Older polysaccharide-only vaccines (like Pneumovax 23) skip this step, which is why they tend to produce weaker protection that fades more quickly, especially in young children.
Who Should Get It
The CDC recommends Prevnar 20 as part of the routine childhood immunization schedule, and also for adults based on age and risk factors. In January 2025, the CDC’s Advisory Committee on Immunization Practices expanded its adult recommendations to include all adults aged 50 and older, in addition to the existing recommendation for adults 65 and older. Adults aged 19 through 49 with certain risk factors, such as chronic heart or lung disease, diabetes, immune-suppressing conditions, or smoking, are also recommended to receive pneumococcal vaccination.
If you’ve already received Prevnar 13 or Pneumovax 23 in the past, you may still benefit from Prevnar 20, but the timing and need depend on your vaccination history and risk profile. Your provider can determine what makes sense based on what you’ve already received.
Dosing Schedule
For infants, Prevnar 20 is given as a 4-dose series at 2 months, 4 months, 6 months, and 12 through 15 months of age. Children who miss doses or start late can still catch up, though the number of doses and spacing will depend on the child’s age when vaccination begins.
For adults, Prevnar 20 is a single dose. That simplicity is one of its advantages over previous pneumococcal vaccine schedules, which sometimes required two different vaccines given months apart.
Common Side Effects
Prevnar 20’s side effect profile is similar to other injectable vaccines. In post-licensure safety surveillance of U.S. adults, injection-site reactions were the most frequently reported issue, occurring in about 29% to 35% of recipients depending on age group. Pain at the injection site, redness, and fever were the next most common. The large majority of reactions were mild or moderate and resolved on their own.
Among adults 19 to 64, about 15% reported fever. Among adults 65 and older, pain at the injection site and redness each showed up in roughly 13% to 15% of reports. Serious adverse events were rare. One signal that appeared in safety monitoring was Guillain-Barré syndrome, a nerve condition causing temporary weakness, reported at a rate of about 0.5 cases per million doses distributed. That rate is extremely low, and ongoing monitoring continues to track it.
Getting It With Other Vaccines
You can receive Prevnar 20 at the same appointment as your flu shot. A phase 3 clinical trial found that giving Prevnar 20 and the influenza vaccine together produced immune responses that were just as strong as giving them separately, for all 20 pneumococcal strains and all four flu strains tested. Side effects were slightly more common with co-administration: mild to moderate fatigue was reported by about 20% of people who got both shots at once, compared to 11% to 13% of those who got them separately. That difference wasn’t considered clinically significant, and no serious adverse events were linked to co-administration.
This makes it practical to stay up to date on both vaccines during a single visit, particularly in fall when flu season begins and pneumococcal disease also tends to rise.