Pre-pandemic live-attenuated influenza vaccine
DH He1; APY Chiu1; JTK Wu2; BJ Cowling2
1 Department of Applied Mathematics, The Hong Kong Polytechnic University
2 WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong
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.