Prevnar (PCV7) was a heptavalent vaccine, meaning that it contains the cell capsule sugars of seven serotypes of the bacteria "S. pneumoniae" (4, 6B, 9V, 14, 18C, 19F, and 23F), conjugated with diphtheria proteins. It was manufactured by Wyeth (which was acquired by Pfizer). Prevnar was approved for use in the United States in February 2000, and vaccination with Prevnar was recommended for all children younger than two years, and for unvaccinated children between 24 and 59 months old who were at high risk for pneumococcal infections.