Lessons learnt after the introduction of the seven valent-pneumococcal conjugate vaccine toward broader spectrum conjugate vaccines.

Abstract

The 7-valent pneumococcal conjugate vaccine (PCV7) is currently being introduced in the vaccine schedule of over 90 countries around the world. After the introduction of the PCV7 vaccine in the United States, a reduction of more than 90% of invasive pneumococcal disease (IPD) was reported in vaccinated children under the age of 5 years. Similar findings were reported from other countries. A reduction in community-acquired pneumonia (CAP) of > 40% has also been reported. In children under the age of 5 years, the number of primary medical visits and antibiotic usage for acute otitis media (AOM) decreased by more than 40%. In adults over 65 years of age a significant reduction of 90% in IPD caused by PCV7 serotypes was reported as well. However, after the introduction of PCV7 there were reports of increase of serotypes not included in the vaccine, such as serotype 19A in various Streptococcus pneumoniae-related diseases such as invasive disease, AOM and pneumonia. In addition, serotypes 1, 5, 7F and 19A were more prevalent in complicated cases of CAP. Recently, new vaccines covering additional serotypes such as the 10-valent pneumococcal conjugate vaccine (PCV10) and 13-valent pneumococcal conjugate vaccine (PCV13) were introduced, and are expected to reduce S. pneumoniae-related diseases furthermore.