Pneumonia

Pneumonia kills more than 4 million people a year, with half among children under age 5. It is responsible for the largest number of deaths in children under 5 worldwide. Worldwide, one child dies from pneumonia every 15 seconds. At the other end of the age spectrum, infection, often co-morbid with other conditions, is a significant source of mortality in the elderly.

Around 5-10% of adults and 20-40% of children have the bacteria Streptococcus pneumoniae (or pneumococcus) in the nasopharynx, without adverse effect. However, infection can migrate/occur elsewhere, notably in the sinuses, ear and lungs, leading to sinusitis, otitis media and pneumonia respectively. It is one of the two prime bacterial causes of meningitis.

Despite the availability of antibiotics, death rates once invasive infection has occurred is around 14%. Antibiotics can often treat infections, especially in otherwise healthy groups, when therapy is initiated quickly. The ß lactams/broad spectrum penicillins were effective through the 1960’s, since when resistance has emerged. A varying proportion of strains are resistant to cephalosporins, macrolides (such as erythromycin), tetracycline, clindamycin and the quinolones. Most isolates remain susceptible to vancomycin, though its use in a β-lactam-susceptible isolate is less desirable because of tissue distribution of the drug and concerns of development of vancomycin resistance.

There are currently nearly 100 serotypes of Streptococcus pneumonia in circulation. Surveillance studies show that the relative prevalence rates between strains alter over time, including with the emergence of new strains.

Wyeth (now Pfizer) launched Prevnar as a prophylactic, initially as a septavalent product. It is a pneumococcal conjugate vaccine (PCV 7). It is typically used in infants, at risk children and the over 65’s. PCV 7 was designed to cover the 7 most prevalent US serotypes in the under 5’s. A 13-valent version has subsequently been developed, to provide greater breadth.

Merck has developed Pneumovax, a 23-valent product. It is a pneumococcal polysaccharide vaccine (PPV 23). However, it elicits a relatively weak antibody response and is ineffective in infants, a key target group.

Multivalent products designed for specific serotypes leaves scope for other serotypes to grow in prevalence. In addition, the manufacturing process militates to the cost of goods being high.

Given the significant unmet needs, ImmBio therefore initiated a vaccine development programme, utilising the key benefit of HspC technology presenting a broad range of antigens, hence providing cross-strain protection, cost-effectively.