Pneumococcal capsular polysaccharides were discovered in 1916-1917, but it took researchers until 1927 to realize that the polysaccharides could induce an immune response. The first pneumococcal polysaccharide vaccine contained pneumococcal strain 1 and strain 2, and the vaccine was administered to nearly 120,000 Civilian Conservation Corp (CCC) men in the 1930s as part of several clinical trial studies. The vaccine’s effectiveness was studied for only a few months and no long-term studies were ever completed.
In 1937, a polysaccharide vaccine containing pneumococcal strain (serotype) 1 was used during a pneumonia outbreak at an adult psychiatric hospital. This trial reported that the vaccine significantly decreased pneumonia rates.
Both military and civilian clinical trials of polysaccharide pneumococcal vaccines reported favorable results, and in 1947, the first pneumococcal polysaccharide vaccine licenses were granted to E.R. Squibb & Sons. Squibb’s adult vaccine contained serotypes 1, 2, 3, 5, 7 and 8 while its pediatric vaccine contained serotypes 1, 4, 6, 14, 18 and 19.
Use of these vaccines was short-lived as doctors preferred to use newly discovered antibiotics to treat pneumonia. Production of polysaccharide pneumococcal vaccines ended in 1951 and in 1954, Squibb withdrew its vaccine license due to the lack of demand for the product.
