Neglected Diseases
Pneumonia is an infection of the lungs that is transmitted when infected individuals cough or sneeze. Symptoms include coughing, fever, chest pain and shortness of breath. The illness can be deadly, especially for young children and elderly patients. Although pneumonia can be caused by a range of pathogens, pneumococcal pneumonia caused by the bacterium Streptococcus pneumoniae is by far the most common in developing countries.
Bacterial meningitis is an infection of the fluid that surrounds the brain and spinal cord, most commonly caused by S. pneumoniae or Neisseria meningitidis. Symptoms of bacterial meningitis can include severe headaches, fever, chills, a stiff neck, nausea and vomiting, sensitivity to light, and an altered mental state. Bacterial meningitis is also often transmitted from person to person through coughing or sneezing. Even with early diagnosis and treatment, 5-10% of infected individuals die within 48 hours of showing symptoms.
Pneumococcal conjugate vaccines (PCVs) are highly effective and have been rolled out in LMICs with favourable results with support from Gavi. However, they are typically expensive to manufacture. There is a need for low-cost candidates that offer broader protection for children against serotypes predominant in LMICs, as gains from existing PCVs are threatened by serotype replacement. Two potential approaches – non-conjugate protein-and whole-cell-based vaccines, both potentially offering broader protection and cheaper manufacturing cost, are being explored; but majority of candidates remain in preclinical development. The introduction of the MenAfriVac monovalent conjugate meningitis A vaccine culminated in a drastic reduction in meningitis A infection across the African continent, but other serogroups have become more prominent, creating the need for low-cost polyvalent vaccine candidates. Rapid diagnostic tests that can detect serogroups to guide vaccine response and multi-pathogen point-of-care tests to guide case management in both epidemic and endemic settings are also needed.
MenFive, a pentavalent meningococcal vaccine co-developed by PATH and the Serum Institute of India was prequalified by the WHO following strong safety and immunogenicity in a Phase III trial conducted among participants aged 2-29 years in Mali and the Gambia. Almost all participants displayed an immune response to serogroup X, making this the first meningococcal vaccine to protect against this specific strain, which is becoming increasingly important as its prevalence increases across the African meningitis belt. In April 2023, the US FDA approved Pfizer’s PREVNAR 20 vaccine, a 20-valent pneumococcal conjugate vaccine for infants and children. The vaccine is yet to be prequalified by the WHO and is not a part of Gavi’s portfolio, meaning LMIC access remains limited.