Tweet
Epidemiology and Infection / Volume 140 / Issue 12 / December 2012, pp 2210-2222
DOI: http://dx.doi.org/10.1017/S0950268812000076 (About DOI), Published online: 07 February 2012
Investigating the effect of high spring incidence of pandemic influenza A(H1N1) on early autumn incidence
H. BURKOMa1 c1, K. KNISSa2, M. MELTZERa3, L. BRAMMERa2, Y. ELBERTa1, L. FINELLIa2 and D. SWERDLOWa4
a1 Johns Hopkins Applied Physics Laboratory, National Security Technology Department, Laurel, MD, USA
a2 Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Infectious Diseases, Influenza Division, Atlanta, GA, USA
a3 Centers for Disease Control and Prevention, National Center for Zoonotic and Infectious Diseases, Division of Preparedness and Emerging Infections, Atlanta, GA, USA
a4 Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Infectious Diseases, Office of the Director, Atlanta, GA, USA
SUMMARY
A pandemic H1N1 infection wave in the USA occurred during spring 2009. Some hypothesized that for regions affected by the spring wave, an autumn outbreak would be less likely or delayed compared to unaffected regions because of herd immunity. We investigated this hypothesis using the Outpatient Influenza-like Illness (ILI) Network, a collaboration among the Centers for Disease Control and Prevention, health departments, and care providers. We evaluated the likelihood of high early autumn incidence given high spring incidence in core-based statistical areas (CBSAs). Using a surrogate incidence measure based on influenza-related illness ratios, we calculated the odds of high early autumn incidence given high spring incidence. CBSAs with high spring ILI ratios proved more likely than unaffected CBSAs to have high early autumn ratios, suggesting that elevated spring illness did not protect against early autumn increases. These novel methods are applicable to planning and studies involving other infectious diseases.
DOI: http://dx.doi.org/10.1017/S0950268812000076 (About DOI), Published online: 07 February 2012
Investigating the effect of high spring incidence of pandemic influenza A(H1N1) on early autumn incidence
H. BURKOMa1 c1, K. KNISSa2, M. MELTZERa3, L. BRAMMERa2, Y. ELBERTa1, L. FINELLIa2 and D. SWERDLOWa4
a1 Johns Hopkins Applied Physics Laboratory, National Security Technology Department, Laurel, MD, USA
a2 Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Infectious Diseases, Influenza Division, Atlanta, GA, USA
a3 Centers for Disease Control and Prevention, National Center for Zoonotic and Infectious Diseases, Division of Preparedness and Emerging Infections, Atlanta, GA, USA
a4 Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Infectious Diseases, Office of the Director, Atlanta, GA, USA
SUMMARY
A pandemic H1N1 infection wave in the USA occurred during spring 2009. Some hypothesized that for regions affected by the spring wave, an autumn outbreak would be less likely or delayed compared to unaffected regions because of herd immunity. We investigated this hypothesis using the Outpatient Influenza-like Illness (ILI) Network, a collaboration among the Centers for Disease Control and Prevention, health departments, and care providers. We evaluated the likelihood of high early autumn incidence given high spring incidence in core-based statistical areas (CBSAs). Using a surrogate incidence measure based on influenza-related illness ratios, we calculated the odds of high early autumn incidence given high spring incidence. CBSAs with high spring ILI ratios proved more likely than unaffected CBSAs to have high early autumn ratios, suggesting that elevated spring illness did not protect against early autumn increases. These novel methods are applicable to planning and studies involving other infectious diseases.
