title: A universal long-term flu vaccine may not prevent severe epidemics.
abstract: BACKGROUND
  Recently, the promise of a new universal long-term flu vaccine has become more tangible than ever before. Such a vaccine would protect against very many seasonal and pandemic flu strains for many years, making annual vaccination unnecessary. However, due to complacency behavior, it remains unclear whether the introduction of such vaccines would maintain high and stable levels of vaccination coverage year after year.
  
  
  RESULTS
  To predict the impact of universal long-term flu vaccines on influenza epidemics we developed a mathematical model that linked human cognition and memory with the transmission dynamics of influenza. Our modeling shows that universal vaccines that provide short-term protection are likely to result in small frequent epidemics, whereas universal vaccines that provide long-term protection are likely to result in severe infrequent epidemics.
  
  
  CONCLUSIONS
  Influenza vaccines that provide short-term protection maintain risk awareness regarding influenza in the population and result in stable vaccination coverage. Vaccines that provide long-term protection could lead to substantial drops in vaccination coverage and should therefore include an annual epidemic risk awareness programs in order to minimize the risk of severe epidemics.
authors.affiliation: RAND Corporation, Santa Monica, California, USA. rvardava@rand.org.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Vardavas
authors.forename: Romulus
authors.initials: R
authors.lastname: Breban
authors.forename: Sally
authors.initials: S
authors.lastname: Blower