Pneumococcal disease remains one of the leading causes of serious bacterial infections worldwide. Caused by the bacterium Streptococcus pneumoniae, it can lead to illnesses ranging from ear infections to life-threatening bloodstream infections and meningitis. Fortunately, effective vaccines are available to significantly reduce the risk of severe disease, especially among older adults and individuals with chronic health conditions.
Understanding who is at risk, how the vaccines work, and current vaccination recommendations can help protect both individuals and communities.
Pneumococcal disease is caused by Streptococcus pneumoniae, a Gram-positive diplococcus that commonly colonizes the upper respiratory tract. While many people carry the bacteria without becoming ill, it can invade other parts of the body and cause serious infections.
Common illnesses caused by S. pneumoniae include:
Among these conditions, pneumonia is the most common and is a major cause of hospitalization and death.
Pneumococcal disease continues to place a significant burden on healthcare systems.
Each year in the United States:
In fact, Streptococcus pneumoniae remains the leading cause of death from community-acquired pneumonia (CAP) in the United States.
Not everyone has the same risk of developing severe pneumococcal disease. The Advisory Committee on Immunization Practices (ACIP) categorizes patients into different risk groups to guide vaccination recommendations.
Adults younger than 65 years who have no chronic medical conditions are considered average risk.
For these individuals, routine pneumococcal vaccination is generally not recommended.
Adults between 19 and 64 years of age with certain chronic medical conditions are at increased risk and should receive vaccination.
Risk factors include:
Although these conditions increase susceptibility, individuals in this group do not have significant immune compromise.
The highest-risk category includes:
Among these groups, adults living with HIV have an approximately 100-fold higher risk of invasive pneumococcal disease compared with age-matched individuals without HIV.
Two pneumococcal vaccines have traditionally been used to protect against invasive disease.
PPSV23 is a purified polysaccharide vaccine that protects against 23 pneumococcal serotypes, covering approximately 90% of bacteremic pneumococcal disease.
Because it produces a less robust immune response in very young children, it is not licensed for children younger than 2 years of age.
PCV13 is a conjugate vaccine, meaning the bacterial polysaccharides are attached to a protein carrier that stimulates a stronger immune response.
Although it protects against 13 serotypes, these represent approximately 70% of bacteremic disease, and the vaccine produces a more durable immune response than PPSV23. PCV13 has been routinely used in childhood immunization programs for many years.
Pneumococcal vaccines are designed specifically to protect against Streptococcus pneumoniae.
They do not protect against pneumonia caused by other organisms, including:
This is an important distinction, as pneumonia can be caused by many different bacteria and viruses.
The vaccination schedule depends on a person’s age and underlying health conditions.
For adults who have never been vaccinated:
If PPSV23 was first administered after age 65, an additional PPSV23 dose is generally unnecessary.
Adults aged 19–64 years who have chronic medical conditions but are not immunocompromised typically receive:
Individuals with immune compromise, HIV, asplenia, chronic renal failure, nephrotic syndrome, malignancy, or those receiving immunosuppressive therapy follow a more intensive schedule:
These additional doses help maintain protection because antibody levels decline more rapidly in high-risk individuals.
Like all vaccines, pneumococcal vaccines may cause side effects, but they are generally mild and short-lived.
The most common reactions are localized to the injection site and include:
These occur in approximately 30% to 50% of recipients.
Systemic symptoms such as fever and muscle aches are less common.
For PPSV23, fever and muscle aches occur in less than 1% of recipients. PCV13 is associated with higher rates of these symptoms in children (approximately 11% to 40%), while adults experience side effects at rates similar to PPSV23.
Severe allergic reactions and other life-threatening adverse events are extremely rare.
