Clinical backgroundStreptococcus pneumoniae (commonly referred to as pneumococcus) is a major cause of serious illness and death worldwide. The biggest burden of pneumococcal childhood infections is in children living in the developing world, especially in Africa & India. Infection is predominantly of the respiratory tract (acute otitis media-AOM, sinusitis, and pneumonia); however, invasive pneumococcal diseases (IPDs) may occur in the form of bacteremia, sepsis, meningitis, or other organ systems involvement (e.g., peritonitis, or hemolytic uremic syndrome). Based on recent estimates, more than 65,000 Indian children died from pneumococcal disease in 2012. Many more were hospitalized
The spectrum of pneumococcal disease (PD) severity can vary from mild to life-threatening in healthy and immunocompromised hosts alike. . Prior to use of vaccinations , the World Health Organization (WHO) estimates that 0.7 to 1 million global pneumococcal deaths and 14.5 million global pneumococcal cases per year occurred in children (uninfected with HIV) younger than 5 years, in 2000. The exact disease burden in India continues to be challenging and remained undiminished and there has been and no descriptive published data available at national level, unfortunately.
The rationale for childhood immunization is to protect children against life-threatening IPDs such as sepsis, meningitis, bacteremic pneumonia, and etc. Pediatricians and primary care practitioners’ advocates pneumococcal vaccines which are not adopted in the universal immunization program at national level. There is no ongoing comprehensive PD surveillance nor on the prevalence and distribution of different serotypes (STs) causing IPDs in India. Nonetheless, a limited number of STs causes most IPDs worldwide. The STs included in existing pneumococcal vaccines are responsible for 49–88% of deaths in developing countries of Africa and Asia where PD morbidity and mortality remains the highest.
Historical Background of Pneumococcus VaccinesContrasting to the “immunization-success story” that is being achieved with a single serotype Haemophilus influenzae type b (Hib) vaccine, the pneumococcus prevention is difficult and burdensome. The PDs are caused by > 90 STs on the basis of its unique polysaccharide antigenic capsules to induce type-specific antibodies that enhanced opsonization, phagocytosis, and killing of S. pneumoniae.