Pre-pandemic live-attenuated influenza vaccine

Abstract

KEY MESSAGES 1. During the 2009 influenza pandemic in Hong Kong, matched vaccines for the pandemic strain were not available until 8 months after its start. We described the potential use of pre-pandemic seasonal vaccine to mitigate the next pandemic. 2. We used an age-structured epidemic model to identify the optimal timing and age-specific allocation strategies for administration of vaccinations. 3. With a stockpile of 200 000 doses, if we start vaccinating those aged 5 to 9 years and 15 to 19 years on day 1, the maximum peak time delayed is 17.4 days and the peak height reduction is 16.8%, compared with no vaccination. 4. If we start vaccinating on 98.8th day, the maximum reduction in death is 13.85% by vaccinating those aged 5 to 9 years and 15 to 19 years. The maximum reduction in hospitalisation is 15.00% by vaccinating those aged 5 to 19 years. 5. In future influenza pandemic with limited vaccine stockpile, vaccinating those aged 5 to 19 years one week before the major wave can minimise the number of hospitalisations and deaths. Vaccination campaign should be started early in order to delay the arrival of a major wave of infections and reduce its height.