Implications of vaccination and waning immunity.
Title | Implications of vaccination and waning immunity. |
Publication Type | Journal Article |
Year of Publication | 2009 |
Authors | Heffernan JM, Keeling MJ |
Journal | Proceedings. Biological sciences / The Royal Society |
Volume | 276 |
Issue | 1664 |
Pagination | 2071-80 |
Date Published | 2009 Jun 7 |
ISSN | 0962-8452 |
Keywords | Communicable Disease Control, Disease Outbreaks, Humans, Immunity, Measles, Models, Immunological, Time Factors, Vaccination |
Abstract | For infectious diseases where immunization can offer lifelong protection, a variety of simple models can be used to explain the utility of vaccination as a control method. However, for many diseases, immunity wanes over time and is subsequently enhanced (boosted) by asymptomatic encounters with the infection. The study of this type of epidemiological process requires a model formulation that can capture both the within-host dynamics of the pathogen and immune system as well as the associated population-level transmission dynamics. Here, we parametrize such a model for measles and show how vaccination can have a range of unexpected consequences as it reduces the natural boosting of immunity as well as reducing the number of naive susceptibles. In particular, we show that moderate waning times (40-80 years) and high levels of vaccination (greater than 70%) can induce large-scale oscillations with substantial numbers of symptomatic cases being generated at the peak. In addition, we predict that, after a long disease-free period, the introduction of infection will lead to far larger epidemics than that predicted by standard models. These results have clear implications for the long-term success of any vaccination campaign and highlight the need for a sound understanding of the immunological mechanisms of immunity and vaccination. |
DOI | 10.1098/rspb.2009.0057 |
Alternate Journal | Proc. Biol. Sci. |