Viral vaccines for the prevention of childhood pneumonia in developing nations: priorities and prospects.

In concert with bacteria, respiratory viruses play a major role in the high rates of acute lower respiratory infection (ALRI) experienced in developing nations. Respiratory syncytial virus, parainfluenza and influenza viruses, and the adenoviruses are the predominant viral causes of ALRI in both developed and developing regions. In this review, the epidemiologic data from developing nations for these viral infections are summarized and the current status of viral vaccines for prevention of ALRI are described. Among the questions to be addressed before these vaccines are used in developing nations are (1) the age-specific rates of infection and disease, (2) the effect of high-dose early exposure to these viruses, and (3) the effect of malnutrition on the immunogenicity of the vaccines. Prospective family studies and other community-based approaches will be required in the acquisition of these data.