ARIVAC Trial: Effectiveness of an 11-valent pneumococcal conjugate vaccine against pneumonia in Philippine children

Clinical Features

Pneumonia, an inflammation of the lung, is characterized by cough and fast, difficult breathing. Fever and muscle aches may occur.

Etiologic Agent Streptococcus pneumoniae and Haemophilus influenzae are the leading bacterial pathogens. Other bacteria (Staphylococcus aureus, and gram-negative pathogens) most often affect newborns and malnourished children. Respiratory viruses (RSV, influenza, parainfluenza, and adenovirus) can be identified in approximately a quarter of children with pneumonia but are much less likely to cause fatal infection than are the bacterial pathogens.

Incidence Approximately 10-20% of all children <5 years old in developing countries develop pneumonia each year.

Sequelae Each year, acute respiratory infections cause approximately 2-3 million deaths among children <5 years old and are the leading cause of death in this age group. About 1% of pneumonia cases result in sequelae (e.g., bronchiectasis), which increases the risk of recurrent infections.

Transmission Person-to-person transmission may occur by direct contact with infectious secretions. Most cases of pneumonia among children occur sporadically, not in outbreaks.

Risk Groups Infants (especially premature or low birth weight). Nearly 75% of pneumonia deaths occur among infants under 1 year old. Risk also increases with malnutrition, malaria, and suppressed immunity.

Trends There has been some decrease in the number of pneumonia deaths over the last decade due to more widespread use of antibiotics.

Challenges Widespread training of health workers, assuring antibiotic supply, and identifying strategies to promote global use of S.pneumoniae vaccines.

Opportunities Conjugate vaccines for S.pneumoniae offer the best opportunity to prevent morbidity and mortality.

©2006 ARIVAC Consortium