pneumococcal 13-valent conjugate vaccine
Prevnar 13 is a conjugate vaccine that protects against disease caused by 13 serotypes of Streptococcus pneumoniae, including invasive pneumococcal disease, pneumonia, and otitis media. It is used in infants and children from six weeks of age and in adults 18 years and older.
This page is based on the FDA labeling for Prevnar 13, cross-checked with the National Cancer Institute dictionary; the mechanism is explained in plain language, and analogies are used only where they stay accurate.
How it works
Explains what the medicine does in the body, not dosing, side effects, or safety.
An analogy
The vaccine is a wanted poster showing the immune system thirteen different bacterial coats. Each coat sugar is stapled to a carrier protein that grabs the attention of even a young infant's immune system. The body files the sketches, builds matching antibodies, and if the real bacterium shows up wearing one of those coats, it is neutralised before it can cause invasive disease.
In simple terms
Prevnar 13 contains capsular polysaccharides from 13 serotypes of Streptococcus pneumoniae, each chemically linked to a nontoxic diphtheria cross-reactive material carrier protein called CRM197. Conjugating the sugars to this protein converts them into a form of antigen that young children can respond to strongly. After vaccination, the immune system produces antibodies against all 13 serotypes, providing active immunization against pneumococcal disease - the invasive disease, pneumonia and otitis media (ear infections) the covered serotypes cause. The vaccine does not protect against serotypes that are not included.
In depth
The pneumococcal 13-valent conjugate vaccine contains capsular antigen polysaccharides derived from Streptococcus pneumoniae serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F, individually conjugated to a nontoxic diphtheria cross-reactive material carrier protein, CRM197. Upon vaccination it induces active immunization against these 13 serotypes, generating serotype-specific antibodies that protect against pneumococcal disease. The conjugate design elicits a T-cell dependent immune response, which is why the vaccine can be used in infants from six weeks of age and in adults 18 years and older; the NCI dictionary notes it has also been studied in immunocompromised patients.
See it in motion
A schematic animation of the mechanism — simplified for clarity, not drawn to scale.
How conjugate vaccines train the immune system
- A sugar coat from the bacterium is chemically joined to a carrier protein the immune system recognizes well.
- Carrier-protein–specific helper T cells are recruited, and they provide the signals needed for maturation of the B-cell response against the sugar coat.
- Helper T cells activate B cells that then class-switch and mature, producing high-affinity IgG against the sugar.
- Memory B and T cells form, so a later encounter with the real bacterium triggers a fast, protective antibody response.
Target: Streptococcus pneumoniae capsular polysaccharides (13 serotypes)
The sugar coats that distinguish the 13 pneumococcal serotypes covered by the vaccine; each is linked to a carrier protein so the immune system, including young infants, can learn to recognise and attack them.
Approved uses
Approved uses differ by country and change over time. Always follow your local prescribing information.
Approved uses in United States
FDA- For active immunization of children six weeks through five years of age for the prevention of invasive disease caused by Streptococcus pneumoniae serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F, and for the prevention of otitis media caused by serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F
- For active immunization of children six through 17 years of age for the prevention of invasive disease caused by Streptococcus pneumoniae serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F
- For active immunization of adults 18 years of age and older for the prevention of pneumonia and invasive disease caused by Streptococcus pneumoniae serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F
Official sources
The statements on this page trace back to these records.
- DailyMed: PREVNAR 13 official US label
U.S. National Library of Medicine, DailyMed
- National Cancer Institute: pneumococcal 13-valent conjugate vaccine
National Cancer Institute
This page explains how the medicine works — it isn’t the patient leaflet. For anything that applies to you, read the leaflet that came with your medicine or ask your pharmacist.
MedUnfold provides educational content and is not medical advice. Always follow your local prescribing information and healthcare professional.