Prevnar 21 is a vaccine approved by the U.S. Food and Drug Administration (FDA) in June 2024. It protects against specific types of pneumococcal disease caused by Streptococcus pneumoniae bacteria. This approval expands protection for adults.
What Prevnar 21 Protects Against
Prevnar 21 is a pneumococcal conjugate vaccine (PCV) targeting pneumococcal disease. This condition encompasses infections caused by Streptococcus pneumoniae bacteria, leading to serious health issues. These include pneumonia, meningitis (brain and spinal cord infection), and bacteremia (severe bloodstream infection).
The vaccine protects against 21 distinct serotypes of the pneumococcal bacteria. These multiple serotypes cover a significant portion of strains responsible for invasive pneumococcal disease in adults. Targeting these serotypes, Prevnar 21 helps reduce the incidence and severity of these infections.
Who Should Receive the Vaccine
Prevnar 21 is recommended for adults aged 18 and older. Older adults, especially those 65 and above, face an increased risk of pneumococcal disease complications. The vaccine provides a preventative measure for this age group.
Individuals aged 19 to 64 with certain underlying medical conditions also benefit from this vaccination. These conditions increase susceptibility to pneumococcal infections. They include chronic heart disease, chronic lung disease, diabetes mellitus, chronic kidney disease, and chronic liver disease. Those with cerebrospinal fluid leaks, cochlear implants, or immunocompromising conditions should also receive the vaccine.
How the Vaccine Works
Prevnar 21 functions as a conjugate vaccine, enhancing the immune response. It works by chemically linking a specific part of the Streptococcus pneumoniae bacteria, known as a polysaccharide, to a carrier protein. This carrier protein is CRM197, a non-toxic variant of diphtheria toxin.
This conjugation process allows the immune system to recognize bacterial polysaccharides more effectively. The carrier protein helps elicit a T-cell-dependent immune response, effective in adults. This mechanism leads to the production of lasting antibodies against targeted pneumococcal serotypes, providing sustained protection against future infections.
Comparing Pneumococcal Vaccines
The landscape of pneumococcal vaccines includes several options, each with distinct characteristics and coverage. Beyond Prevnar 21, other prominent vaccines are Prevnar 20 (PCV20) and Pneumovax 23 (PPSV23). Prevnar 21 covers 21 serotypes, Prevnar 20 protects against 20, and Pneumovax 23 covers 23 different serotypes.
A key distinction lies in their vaccine type: Prevnar 21 and Prevnar 20 are conjugate vaccines, while Pneumovax 23 is a polysaccharide vaccine. Conjugate vaccines, like Prevnar 21, generally elicit a stronger and more enduring immune response, including immune memory. Polysaccharide vaccines, such as Pneumovax 23, primarily stimulate B cells directly, which may not generate the same level of long-term memory in all age groups.
Prevnar 21 introduces eight serotypes not found in other currently licensed pneumococcal vaccines. However, it does not include serotype 4, which is present in Prevnar 20 and Pneumovax 23. Serotype 4 can be a significant cause of invasive pneumococcal disease in certain geographic areas, particularly among adults with specific risk factors. For adults aged 50 and over who have not previously received a pneumococcal conjugate vaccine, or whose vaccination history is unknown, Prevnar 21 is now an available option. If Prevnar 20 or Prevnar 21 is administered, a subsequent dose of Pneumovax 23 is generally not indicated, simplifying vaccination schedules.
Common Side Effects
Like all vaccines, Prevnar 21 can cause side effects, though they are typically mild and temporary. The most frequently reported reactions occur at the injection site. These include pain, redness, or swelling where the shot was given. These local reactions are common and usually resolve within a few days, indicating the body’s immune system is responding to the vaccine.
Other common side effects can include fatigue, muscle aches, headache, and a low-grade fever. These systemic reactions are also generally mild and signal that the immune system is actively building protection against the targeted bacteria. While serious allergic reactions are possible, they are rare.