Seasonality of Rotavirus Infection with its Vaccination

The impact of rotavirus, the most prevalent diarrheal pathogen in young children worldwide, may be reduced by either a recently approved vaccine or others in development. The dynamics of rotavirus infections are studied using a simple mathematical model that includes the impact of breast feeding, seasonality and the possibility of control via vaccination. Data from Australia are fitted to a model that incorporates the effect of seasonality in the transmission process. The impact of temporary and partially effective vaccines is explored. Finally, the issue of cost is briefly discussed in the context of identifying “optimal” vaccination strategies. 1. On the characteristics of rotavirus Rotavirus spreads easily especially among infants. In fact, 95% of children worldwide are infected by the time they reach age 5 with peak incidence occurring between ages 4 months and 36 months [20]. CDC epidemiologist Umesh Parashar reported at an international meeting on the epidemiology of the rotavirus held in Mexico City (2004) that rotavirus was detected in 60% of stool samples from children hospitalized with severe diarrhea in Vietnam; 41 % in China; 56% in Myanmar; and 29% in Hong Kong [23]. In the United States, approximately 2.7 million children under 5 years of age are infected by rotavirus each year, resulting in 500,000 visits to physicians and 50,000 hospitalizations per year. The estimated direct cost of medical care is about $274 million with $1 billion per year in associated costs in the U.S. alone [21],[28]. In Peru, for example, the total medical care costs directly linked to rotavirus infections are estimated to be around $2.6 million (U.S.) a year [38], an amount that includes the costs associated with 64,000 clinic visits and 30,000 hospitalizations per year. A study presented at the European Society for the Study and Prevention of Infant Death (ESPID) quantified the burden associated with rotavirus disease in the new European Union (EU). Their estimates used a model recently developed by the U.S. Centers for Disease Control and Prevention (CDC). The EU managed to obtain country specific estimates of rotavirus levels of infections in each of its 25 member states [33]. These estimates revealed nearly 4.5 million episodes of rotaviral disease among the 24 million children under 5 years [33]. In other words, about one out of every five children has experienced a rotavirus infection before age 5 within the EU. 1991 Mathematics Subject Classification. Primary 92D30; Secondary 62F25.