Species A rotavirus (RVA) is the leading cause of severe
childhood gastroenteritis worldwide and accounts for about
2 million hospitalizations and 453 000 deaths among young
children annually.1,2
In 2006, the World Health Organization
(WHO) recommended including two RVA vaccines in national
immunization programmes in the Americas and Europe – after
both vaccines had been found to show high efficacy and safety
in clinical trials in these regions.2
By 2009, the same vaccines
had been found to be efficacious in Africa and Asia and WHO
therefore expanded its recommendation to include all children
worldwide.2
Nearly 40 countries – most of them high- or
middle-income – have introduced an RVA vaccine into their
national programmes. Early evaluations after the introduction
of these vaccines in high- or middle-income countries have
shown a drop in hospitalizations for diarrhoea ranging from
33 to 50%.3–9
RVA vaccines have appeared to perform less well
in low-income countries.10–12 The impact of RVA vaccination
in different socioeconomic groups within a single country has
not yet been investigated.
The evaluation of the impact of RVA vaccination in “realworld”
settings is a public health priority. Although the direct
protection conferred by RVA vaccines against RVA infection
needs to be assessed, the broader public health benefits of such
vaccines may be better appreciated by evaluating the impact
of RVA vaccination on hospitalizations for diarrhoea.
The states of Mexico vary in the level of development that
they have achieved and this heterogeneity provides a useful
opportunity to examine possible differences in the impact of
an RVA vaccine across several socioeconomic strata.13 After
the national introduction of a monovalent RVA vaccine in
2007, substantial declines in diarrhoea-related mortality and
morbidity among Mexican children were observed.14,15 In one
study in Mexico, the incidence of hospitalization for diarrhoea
was found to have declined since 2007.16 However, this decline
could not be attributed to RVA vaccination unequivocally
because at the time “postvaccine” data had only been collected
for two years and the incidence of infection with RVA
shows considerable inter-annual variation in the absence of
any interventions.16
In this study we describe trends in hospitalization for
diarrhoea among young children in Mexico before and after
the introduction of RVA vaccination. The primary aims of this
analysis were to document the long-term effect of RVA vaccination
on diarrhoea-related hospitalizations and to compare
the impact of such vaccination in the poorly developed states of
Mexico with that seen in the country’s more developed states.