In June 2015, the US Food & Drug Administration (FDA)’s Center for Biologics Evaluation and Research (CBER) and the US National Institute of Health (NIH)’s National Institute of Allergy and Infectious Disease (NSAID) held a workshop on RSV vaccines development to explore the state of the science and paths forward for developing vaccines in high-income countries for infants and children, pregnant women, and elderly people (those older than age 60 years), with a focus on serological biomarkers and endpoints for vaccine development in these populations.1

Attendees concluded that better tools are needed for assessing the severity of RSV infections, and that prognostic biomarkers are needed for clinical research and for guiding clinical treatment decision-making.1

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Workshop experts also discussed other challenges to RSV vaccine development, including the available evidence base regarding vaccine-induced immune reactions such as enhanced respiratory disease (ERD), which is believed to involve a Th2-biased immune system response.1 (Th-2 immune response involves interleukin 4,5, and 13 cytokines and eosinophil activity, which counteracts other, Th-1 immune responses to infection.)

Vaccine development is now progressing into advance stages of clinical testing for adults, but ERD represents a significant challenge for development of vaccines for infants. While safety and early efficacy data for RSV vaccines are now available for adults and older children—most of whom have experienced RSV infection—ERD risk poses a particular challenge for vaccine development for RSV-naïve neonates.1

“Ultimately, the first clinical study(ies) of non-live candidate vaccines in seronegative infants will need to be carefully designed to rule out a large magnitude risk of ERD before larger pivotal Phase 3 studies are conducted,” cautioned the authors of the workshop report.1

Until a viable vaccine has been developed for RSV-naïve infants, prevention efforts for infants will continue to involve non-vaccine prophylaxis. 

“Fortunately, efforts to expand the scope of such passive prevention are also under active development. Strategies include boosting pregnant women with an RSV vaccine in an effort to raise her neutralizing antibody concentrations. Transplacental transfer of those antibodies may offer protection to infants in their early months. Additional strategies include the development and testing of longer acting monoclonal antibodies for high-risk and term infants born during RSV season. The pace and novelty of the newest work on preventing RSV infection in infants has never been more promising”, added Joseph Domachowske, MD, Professor of Pediatrics, Professor of Microbiology and Immunology, Director of the Global Maternal-Child and Pediatric Health Program at the State University of New York Upstate Medical Center in Syracuse, NY.


1. Roberts JN, Graham BS, Ruth AK, et al. Challenges and opportunities in RSV vaccine development: meeting report from FDA/NIH workshop. Vaccine. 2016;34:4843-4849.

2. US Centers for Disease Control and Prevention (CDC). Respiratory syncytial virus (RSV): Infection and incidence. Accessed October 15, 2016.

3. Figueras-Aloy J, Manzoni P, Paes B, et al. Defining the risk and associated morbidity and mortality of severe respiratory syncytial virus infection among preterm infants without chronic lung disease or congenital heart disease. Infectious Disease Therapy. doi:10.1007/s40121-016-0130-1. Published online September 14, 2016 ahead of print.

4. US Centers for Disease Control and Prevention (CDC). Respiratory syncytial virus (RSV): Clinical description and diagnosis in infants. Accessed October 15, 2016.

5. US National Foundation for Infection Diseases. Respiratory syncytial virus in older adults: a hidden annual epidemic. Accessed October 15, 2016.