Observations regarding historical accounts of pneumococcal diseases due to serotypes 1 and 3
Surveillance of the serotypes causing invasive pneumococcal diseases in the UK has indicated increasing incidence of serotype 1- and serotype 3-related disease in recent years. The introduction of a pneumococcal conjugate vaccine to the paediatric vaccination schedule in 2006, which did not cover these serotypes, has been regarded as a contributing factor. Serotypes 1 and 3 were perhaps the most extensively studied pneumococcal serotypes in the early twentieth century when pneumococcal serotyping began.