Modelling the seasonality of rotavirus disease and the impact of vaccination in England and Wales
Introduction
Rotavirus is the most common cause of acute gastroenteritis in children under 5 years of age [1]. In developed countries, rotavirus gastroenteritis remains a common cause of hospitalization at great cost to health services [2]. In England and Wales, the annual incidence of rotavirus hospitalizations is estimated at 4.5 per 1000 children under the age of 5 years and the cost to the National Health Service estimated to be GBP 14.2 million per year [3].
The second generation of live oral rotavirus vaccines have demonstrated safety and efficacy [4], [5] and are increasingly being used routinely as part of childhood immunization schedules in a number of middle and high income countries [6], [7]. The Rotarix vaccine, made from the most common human serotype G1P1A[8], is recommended by WHO as a two-dose schedule to be given at two and four months of age [8]. RotaTeq, a pentavalent vaccine developed from a bovine rotavirus strain and combined with reassorted strains of human serotypes G1, G2, G3, G4 and P1A[8], is WHO-recommended as a three-dose schedule to be given at two, four and six months of age [8]. In the United States, following the introduction of RotaTeq in 2006, there was a delay in the timing of peak incidence in the 2007–2008 season by two to four months and fewer cases overall compared to previous years [6]. This provides the first indication, post-licensure, that rotavirus vaccination reduces the burden of rotavirus disease in a large population and suggests that vaccination may also have an impact on transmission. Other high and middle income countries which have introduced rotavirus vaccination have shown similar effects [7], [9]. In England and Wales, the introduction of rotavirus vaccination is currently under consideration.
This study aims to develop a dynamic model of rotavirus transmission, and apply it to daily case reports of rotavirus disease from England and Wales. Using this model, we examine the potential epidemiological impact of a rotavirus mass vaccination programme.
Section snippets
Key features of rotavirus epidemiology captured in the model
In temperate countries, most rotavirus disease occurs in late winter or early spring [10]. Rotavirus groups A to C infect humans, and all groups (A to G) infect animals, but animals are not believed to play a role in the transmission to humans [11]. Globally, disease in children is caused predominantly by group A [11]. The virus is transmitted by the faeco-oral route; from person to person directly or via contaminated fomites, food or water [12]. Peak incidence of clinical disease is 6–24
Model fit
Parameters estimated from our model are summarised in Table 2. The force of infection was highest in the 1–4 year olds and lowest in over 5 year olds. The seasonality, age distribution and numbers of reported rotavirus cases predicted by the model were a good fit to the rotavirus surveillance data (Fig. 2, Fig. 3).
Impact of vaccination
An increasing decline in numbers and delay in the start of the rotavirus season is predicted in the first and second post-vaccination years (Fig. 4). Interestingly, there is a slight
Discussion
We found that rotavirus disease patterns in England and Wales can be modelled well by a dynamic model of rotavirus transmission which takes into account the natural history of rotavirus infections. The model reproduces the regular seasonal pattern of rotavirus gastroenteritis and the age distribution of cases seen. Vaccination is expected to reduce the observed seasonal peak in rotavirus disease incidence and reduce the overall burden of disease.
Model fit was obtained by using a cosine function
Acknowledgements
This work was supported by a grant from the Medical Research Council to Dr Atchison. The funding body had no role in the design, conduct, analysis or reporting of the study. The views and opinions expressed in this paper do not necessarily reflect those of the funding body.
References (39)
- et al.
Epidemiological effects of seasonal oscillations in birth rates
Theor Popul Biol
(2007) - et al.
Safety and immunogenicity of RIX4414 live attenuated human rotavirus vaccine in adults, toddlers and previously uninfected infants
Vaccine
(2004) - et al.
Rotavirus and severe childhood diarrhoea
Emerg Infect Dis
(2006) - et al.
Costs of community acquired pediatric rotavirus gastroenteritis in 7 European countries: the REVEAL Study
J Infect Dis
(2007) - et al.
Evaluating rotavirus vaccination in England and Wales: Part I. Estimating the burden of disease
Vaccine
(2007) - et al.
Safety and efficacy of a pentavalent human-bovine (WC3) reassortant rotavirus vaccine
N Engl J Med
(2006) - et al.
Safety and efficacy of an attenuated vaccine against severe rotavirus gastroenteritis
N Engl J Med
(2006) - et al.
Decline and change in seasonality of US rotavirus activity after the introduction of rotavirus vaccine
Pediatrics
(2009) - et al.
Incidence of rotavirus and all-cause diarrhea in Northeast Brazil following the introduction of a national vaccination program
Gastroenterology
(2009) Meeting of the immunization strategic advisory group of experts, April 2009—conclusions and recommendations
Wkly Epidemiol Rec
(2009)