The pneumococcal vaccine protects against infections caused by a common bacterium that lives in the nose and throat and can cause illnesses ranging from ear infections to life-threatening pneumonia, meningitis, and bloodstream infections. Several versions of the vaccine exist, each covering a different number of bacterial strains, and the CDC recommends it routinely for young children and adults 50 and older.
What Pneumococcal Disease Looks Like
The bacterium behind pneumococcal disease, Streptococcus pneumoniae, is carried harmlessly in many people’s airways. Problems start when it spreads to parts of the body that are normally sterile. Mild infections include middle ear infections (otitis media) and sinusitis. Serious, invasive infections include pneumonia, meningitis (infection of the membranes surrounding the brain and spinal cord), and bacteremia (infection in the bloodstream).
Young children, older adults, and people with weakened immune systems face the highest risk. Before widespread vaccination began, pneumococcal disease caused an estimated 600,000 child deaths worldwide each year. By 2015, that number had dropped by roughly 51%, with vaccination preventing about 250,000 child deaths, mostly after 2010 when many high-burden countries rolled out immunization programs. According to researchers at Johns Hopkins, the average annual decline in child deaths from pneumococcal disease jumped from 3% per year during 2000 to 2010 to 8% per year after 2010.
Types of Pneumococcal Vaccines
There are currently four pneumococcal vaccines available in the United States, and they fall into two categories based on how they train the immune system.
Conjugate Vaccines (PCV)
Conjugate vaccines attach pieces of the bacterial coating to a protein that the immune system recognizes easily. This triggers a strong, long-lasting response that creates immune memory, meaning your body “remembers” the bacteria and can fight it off quickly if exposed later. This type of vaccine also works well in infants and toddlers, whose immune systems are still developing. Three conjugate vaccines are available:
- PCV15 (Vaxneuvance): protects against 15 strains
- PCV20 (Prevnar 20): protects against 20 strains
- PCV21 (Capvaxive): protects against 21 strains
Polysaccharide Vaccine (PPSV)
The older-style polysaccharide vaccine, PPSV23 (Pneumovax 23), covers 23 strains but works differently. It uses free pieces of the bacterial coating without attaching them to a protein carrier. The immune response it produces is weaker, doesn’t build the same long-term memory, and doesn’t work in children under two. It’s still used in some adult vaccination sequences to broaden strain coverage after a conjugate dose.
How Well the Vaccines Work
Conjugate vaccines are highly effective against invasive pneumococcal disease, the dangerous infections that reach the bloodstream or brain. In the large CAPITA clinical trial, PCV13 (a predecessor to current conjugate vaccines) showed 46% efficacy against vaccine-type community-acquired pneumonia. A 2022 study in adults 65 and older found PCV13 vaccination was associated with a 10% reduction in hospitalizations for all-cause pneumonia, which includes pneumonia caused by bacteria not covered by the vaccine.
The real-world impact is clearest in children. Countries that added conjugate vaccines to their childhood immunization programs saw dramatic drops in invasive pneumococcal disease, not only in vaccinated children but also in unvaccinated adults, because fewer children carrying the bacteria meant less spread through communities.
Who Should Get Vaccinated
Children
The CDC recommends a four-dose series of conjugate vaccine (PCV15 or PCV20) for all children, given at 2 months, 4 months, 6 months, and 12 to 15 months. Children who miss doses or start late can still catch up, though the number of doses and spacing will depend on their age at the time.
Adults
Adults 50 and older who have never received a conjugate pneumococcal vaccine should get one. The options are PCV15, PCV20, or PCV21. If PCV15 is used, the CDC recommends following it with a dose of PPSV23 to broaden protection. PCV20 and PCV21 cover enough strains that they can be given as standalone doses.
People With Higher-Risk Conditions
Certain medical conditions make pneumococcal disease more likely or more dangerous, and people with these conditions qualify for vaccination earlier than the general population. Conditions that apply to both children and adults include:
- Cerebrospinal fluid leaks
- Cochlear implants
- Chronic liver disease
- Diabetes
- Immunocompromising conditions such as HIV, sickle cell disease, absence or dysfunction of the spleen, organ transplant, or treatment with immunosuppressive medications or radiation
For adults specifically, additional qualifying conditions include chronic lung diseases like COPD and asthma, chronic heart conditions such as heart failure, chronic kidney disease, alcoholism, and cigarette smoking. Children with persistent moderate or severe asthma, congenital heart disease, or kidney conditions also qualify.
Side Effects
Pneumococcal vaccines are well tolerated. The most common side effects are mild and typically resolve within one to two days. They include soreness, redness, or swelling at the injection site, along with fatigue, headache, fever, decreased appetite, and drowsiness. Some adults report limited movement in the injected arm, muscle pain, joint pain, or chills. Serious reactions are rare.
Choosing Between Vaccines
If you’re an adult who has never had a pneumococcal conjugate vaccine, the simplest path is a single dose of PCV20 or PCV21, which covers enough strains to stand alone. If your provider uses PCV15 instead, you’ll need a follow-up dose of PPSV23 to fill in the gaps in strain coverage. Your vaccination history matters: if you received an older conjugate vaccine like PCV13 years ago, your provider can help determine whether an additional dose of a newer, broader vaccine is appropriate based on your age and risk factors.
For children, the choice between PCV15 and PCV20 is straightforward since both follow the same four-dose schedule. PCV20 covers more strains, but either option provides strong protection during the years when children are most vulnerable to invasive disease.