Targeting pediatric versus elderly populations for norovirus vaccines: a model-based analysis of mass vaccination options.
Noroviruses are the leading cause of acute gastroenteritis and foodborne diarrheal disease in the United States. Norovirus vaccine development has progressed in recent years, but critical questions remain regarding which age groups should be vaccinated to maximize population impact.



We developed a deterministic, age-structured compartmental model of norovirus transmission and immunity in the U.S.



The model was fit to age-specific monthly U.S. hospitalizations between 1996 and 2007. We simulated mass immunization of both pediatric and elderly populations assuming realistic coverages of 90% and 65%, respectively. We considered two mechanism of vaccine action, resulting in lower vaccine efficacy (lVE) between 22% and 43% and higher VE (hVE) of 50%.



Pediatric vaccination was predicted to avert 33% (95% CI: 27%, 40%) and 60% (95% CI: 49%, 71%) of norovirus episodes among children under five years for lVE and hVE, respectively. Vaccinating the elderly averted 17% (95% CI: 12%, 20%) and 38% (95% CI: 34%, 42%) of cases in 65+ year olds for lVE and hVE, respectively. At a population level, pediatric vaccination was predicted to avert 18-21 times more cases and twice as many deaths per vaccinee compared to elderly vaccination.



The potential benefits are likely greater for a pediatric program, both via direct protection of vaccinated children and indirect protection of unvaccinated individuals, including adults and the elderly. These findings argue for a clinical development plan that will deliver a vaccine with a safety and efficacy profile suitable for use in children.
Epidemiology Branch, Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, United States; Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, United States. Electronic address: molly.steele@emory.edu.
Molly K
MK
Steele
Environmental Health Sciences, School of Public Health, University of California, Berkeley, CA 94720, United States.
Justin V
JV
Remais
Epidemiological Modelling Unit, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne Vic 3004, Australia.
Manoj
M
Gambhir
Epidemiology Branch, Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, United States.
John W
JW
Glasser
Department of Epidemiology and Biostatistics, College of Public Health, University of Georgia, Athens, GA 30602, United States.
Andreas
A
Handel
Epidemiology Branch, Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, United States.
Umesh D
UD
Parashar
Epidemiology Branch, Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, United States; Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA 30322, United States.
Benjamin A
BA
Lopman
D000368:Aged; D017250:Caliciviridae Infections / Q000517:prevention & control*; D002648:Child; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D032541:Mass Vaccination; D029322:Norovirus; D014611:Vaccination; D014612:Vaccines / Q000627:therapeutic use*
D014612:Vaccines
Herd immunity; Mathematical modeling; Norovirus; Transmission; Vaccination