Vaccination strategies against respiratory syncytial virus

PNAS – Proceedings of the National Academy of Sciences of the United States of America
Biological Sciences – Population Biology:
Vaccination strategies against respiratory syncytial virus
Dan Yamin, Forrest K. Jones, John P. DeVincenzo, Shai Gertler, Oren Kobiler, Jeffrey P. ownsend, and Alison P. Galvani
PNAS 2016 ; published ahead of print October 31, 2016, doi:10.1073/pnas.1522597113
The WHO estimates that respiratory syncytial virus (RSV) vaccination will be available in the next 5ā€“10 y. To evaluate the population effectiveness of an RSV vaccination program in the United States, we developed a transmission model that integrates data on daily infectious viral load and behavior changes while symptomatic. Our model simulations demonstrate that vaccinating children younger than 5 y of age will be the most efficient and effective way to prevent RSV infection in both children and older adults, a result that is robust across the US states considered. Accordingly, the population burden of RSV would be most effectively reduced if current vaccine candidates were to focus on children.
Respiratory syncytial virus (RSV) is the most common cause of US infant hospitalization. Additionally, RSV is responsible for 10,000 deaths annually among the elderly across the United States, and accounts for nearly as many hospitalizations as influenza. Currently, several RSV vaccine candidates are under development to target different age groups. To evaluate the potential effectiveness of age-specific vaccination strategies in averting RSV incidence, we developed a transmission model that integrates data on daily infectious viral load and changes of behavior associated with RSV symptoms. Calibrating to RSV weekly incidence rates in Texas, California, Colorado, and Pennsylvania, we show that in all states considered, an infected child under 5 y of age is more than twice as likely as a person over 50 y of age to transmit the virus. Geographic variability in the effectiveness of a vaccination program across states arises from interplay between seasonality patterns, population demography, vaccination uptake, and vaccine mechanism of action. Regardless of these variabilities, our analysis showed that allocating vaccine to children under 5 y of age would be the most efficient strategy per dose to avert RSV in both children and adults. Furthermore, due to substantial indirect protection, the targeting of children is even predicted to reduce RSV in the elderly more than directly vaccinating the elderly themselves. Our results can help inform ongoing clinical trials and future recommendations on RSV vaccination.