8 July 2019Results from 7-country PERCH study highlight the need for new vaccines, especially against respiratory syncytial virus
Respiratory syncytial virus (RSV) and other viruses now appear to be the main causes of severe childhood pneumonia in low- and middle-income countries, highlighting the need for vaccines against these pathogens, according to a study from a consortium of scientists around the world.
Led by the International Vaccine Access Center in the Johns Hopkins Bloomberg School of Public Health, the consortium brought together more than a dozen institutions and programs, including the Medical Research Council Unit The Gambia at LSHTM.
While much progress has been made to reduce childhood pneumonia, it remains the leading cause of death worldwide among children under 5 years old with about 900,000 fatalities and more than 100 million reported cases each year. This makes pneumonia a greater cause of childhood mortality than malaria, tuberculosis, HIV, Zika virus, and Ebola virus combined.
The main causes of pneumonia today are not the same as they were in past decades, in part due to successful vaccines against H. influenzae and pneumococcal disease. New estimates about what causes severe pneumonia are critical for decision makers involved in the fight against pneumonia.
The study, published June 27th 2019 in The Lancet, was the largest and most comprehensive of its kind since the 1980s. The Pneumonia Etiology Research for Child Health (PERCH) study included nearly 10,000 children in Bangladesh, The Gambia, Kenya, Mali, South Africa, Thailand, and Zambia.
Associate Professor Stephen Howie, who led the PERCH Study in The Gambia, said “The MRC Unit The Gambia at LSHTM has a proud history of relevant and readily translatable research in international child health, and we are delighted to be an integral part of the landmark PERCH Study, in partnership with the Government and people of The Gambia, and the whole PERCH team. It is exciting that these important results are now being released: we believe they will help accelerate progress preventing deaths from pneumonia, and so contribute to children worldwide surviving and thriving.”
Severe child pneumonia was caused more often by viruses
After testing for viruses, bacteria, and fungi in children with severe hospitalized pneumonia—and in community children without pneumonia—the study found that 61% of severe pneumonia cases were caused by viruses led by RSV, which alone accounted for 31% of cases.
PERCH estimated that RSV accounted for nearly a third of all cases and was the leading cause of severe pneumonia in each of the seven countries studied. Other top causes were rhinovirus, human metapneumovirus, parainfluenza viruses, and S. pneumoniae bacteria.
PERCH will impact how we prevent, diagnose, and treat pneumonia in the 21st century
RSV has long been known as a common and potentially serious respiratory germ among children and the elderly. Several RSV vaccine candidates are being developed and evaluated in clinical trials. A monoclonal antibody therapy, palivizumab, is available for the prevention of RSV disease in children with underlying medical conditions but is not suitable programmatically or financially for widespread use in routine immunization programs.
Bacteria, cumulatively, caused a substantial proportion of disease and, being treatable and commonly fatal, should remain a target for early access to treatment.
Yet with PERCH results showing that viral causes predominate and with the development of new tools to help identify the causes of pneumonia, treatment standards may be revised to tailor therapy and reduce unnecessary antibiotic use.
Many institutions worked together to standardize protocols and and train hundreds of laboratory technicians, nurses, and other health workers who developed cutting-edge skills.
Katherine O’Brien, MD led the PERCH study as executive director for the International Vaccine Access Center (IVAC) at the Johns Hopkins Bloomberg School of Public Health and now serves as Director of Immunizations, Vaccines and Biologicals at the World Health Organization. PERCH also engaged the University of the Witwatersrand; Kenya Medical Research Institute-Wellcome Trust Research Programme; University of Oxford; University of Maryland School of Medicine and Centre pour le Développement des Vaccins-Mali; Thailand Ministry of Public Health collaboration with U.S. Centers for Disease Control and Prevention; Boston University School of Public Health and University Teaching Hospital, Lusaka; Medical Research Council Unit The Gambia at LSHTM; University of Otago and Canterbury Health Laboratories; and The Emmes Corporation.
Read the PERCH results in The Lancet: Causes of severe pneumonia requiring hospital admission in children without HIV infection from Africa and Asia: the PERCH multi-country case-control study.