PCV13 contains polysaccharides of the capsular antigens of Streptococcus pneumoniae serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F, individually conjugated to a nontoxic diphtheria CRM197 (CRM, cross-reactive material) carrier protein. A 0.5-mL PCV13 dose contains approximately 2 μg of polysaccharide from each of 12 serotypes and approximately 4 μg of polysaccharide from serotype 6B; the total concentration of CRM197 is approximately 34 μg. The vaccine contains 0.125 mg of aluminum as aluminum phosphate adjuvant and no thimerosal preservative. PCV13 is administered intramuscularly and is available in single-dose, prefilled syringes that do not contain latex.2