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Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 106(8): 907-911, December 2011
Species A rotavirus (RVA) disease is a leading cause
of childhood mortality in the world, accounting for an es-
timated 527,000 deaths annually among children young-
er than five years of age (Parashar et al. 2009). In 2006,
clinical trials conducted in the Americas and Europe
demonstrated that two new RVA vaccines had efficacy of
85-98% against severe RVA diarrhoea (Ruiz-Palacios et
al. 2006, Vesikari et al. 2006). Subsequently, these RVA
vaccines, Rotarix® [(RV1), monovalent G1P(8)] (Glaxo-
SmithKline Biologicals, Rixensart, Belgium) and Ro-
taTeq® [(RV5) pentavalent G1, G2, G3, G4P(8)] (Merck
Vaccines, Whitehouse Station, NJ, USA) (Soares-Weiser
et al. 2010), were recommended for use in children of
Europe and the Americas for preventing RVA diarrhoea
(WHO 2007). By January 2011, 13 of the 24 countries
routinely offering RVA vaccine as part of the national
immunization schedule were in Latin America.
In 1999, a previous RVA vaccine, RotaShield, was
withdrawn from the United States (US) market because
of its association with intussusception. The risk of in-
tussusception with both current RVA vaccines, RV5 and
RV1, was evaluated pre-licensure in clinical trials of
60,000-70,000 infants each (designed to assess a risk
similar to RotaShield) and no risk was observed. In re-
cent months, vaccine safety came under scrutiny after
a post-licensure evaluation identified a short-term four-
six-fold elevated relative risk of intussusception in the
first-seventh days following dose 1 of RV1 in Mexico
(Colindres 2010, Patel et al. 2011) and with both RV1 and
RV5 in Australia (Buttery et al. 2011). These risks are
substantially lower than the 30-fold increased risk in the
first week after dose 1 of RotaShield (WHO 2010).
With these new risk data, ministries of health need
real-world RVA vaccine benefits data to determine
whether to introduce or continue RVA vaccination pro-
grams. This report summarizes Latin American hospi-
tal-based and national surveillance network data; high-
lighting the reduction in gastroenteritis and RVA disease
burden as well as identifying changes in RVA epidemiol-
ogy, following RVA vaccine introduction.
Vaccine effectiveness estimates from case-control
studies and vaccine impact data from population-based
time-trend analysis of RVA vaccines used currently in Lat-
in America were evaluated. Studies were identified using
a country-specific publication search strategy and were
reviewed and organized by study design (disease burden
trend analysis versus case-control) and by disease outcome
(gastroenteritis deaths, gastroenteritis hospitalizations and
RVA hospitalizations). Gross national income data was ob-
tained from the World Bank and reported for the country
of origin for each study. For disease burden trend analy-
sis studies, published estimates of vaccine coverage and
percent reduction in disease after vaccine implementation
+ Corresponding author: email@example.com
Received 25 October 2011
Accepted 16 November 2011
Reduction in morbidity and mortality from childhood diarrhoeal
disease after species A rotavirus vaccine introduction
in Latin America – A Review
Rishi Desai1/+, Lucia Helena de Oliveira2, Umesh D Parashar1,
Benjamin Lopman1, Jacqueline E Tate1, Manish M Patel1
1Division of Viral Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd NE, MS-A47, 30333 Atlanta, GA, USA
2Pan American Health Organization, Washington, DC, USA
Countries in Latin America were among the first to implement routine vaccination against species A rotavirus
(RVA). We evaluate data from Latin America on reductions in gastroenteritis and RVA disease burden following the
introduction of RVA vaccine. Published literature was reviewed to identify case-control studies of vaccine effective-
ness and population-based studies examining longitudinal trends of diarrhoeal disease reduction after RVA vaccine
introduction in Latin American countries. RVA vaccine effectiveness and impact on gastroenteritis mortality and
hospitalization rates and RVA hospitalization rates are described. Among middle-income Latin American countries
with published data (Mexico, Brazil, El Salvador and Panama), RVA vaccine contributed to a gastroenteritis-asso-
ciated mortality reduction of 22-41%, a gastroenteritis-associated hospitalization reduction of 17-51% and a RVA
hospitalization reduction of 59-81% among children younger than five years of age. In Brazil and El Salvador, case-
control studies demonstrated that a full RVA vaccination schedule was 76-85% effective against RVA hospitalization;
a lower effectiveness of 46% was seen in Nicaragua, the only low-income country with available data. A growing
body of literature offers convincing evidence of “real world” vaccine program successes in Latin American settings,
which may be expanded as more countries in the region include RVA vaccine in their immunization programs.
Key words: species A rotavirus - rotavirus - vaccines - Latin America
Species RVA vaccine in Latin America • Rishi Desai et al.
were reported. For case-control studies, full vaccine series
was defined as three doses of RV5 or two doses of RV1 and
partial vaccine series was defined as one or two doses of
RV5 or one dose of RV1. Additionally, the most prevalent
RVA genogroup causing gastroenteritis among cases en-
rolled in the case-control study was abstracted. Individual
study results and ranges were summarized.
Ethics - This study did not require Institutional Re-
view Board clearance.
Population-based time-trends of gastroenteritis
burden before and after vaccine implementation - Four
middle income countries in Latin America (Brazil, El
Salvador, Mexico and Panama) have published reports
on population-based time-trends of gastroenteritis and/or
RVA disease burden reductions after RVA vaccine intro-
duction (de Palma et al. 2010, Lanzieri et al. 2010, 2011,
Richardson et al. 2010, Sáfadi et al. 2010, do Carmo et al.
2011, Molto et al. 2011, Quintanar-Solares et al. 2011, Yen
et al. 2011a) (Table I). In these countries, vaccine coverage
among infants younger than one year of age with at least
one dose of RVA vaccine ranged from 74-94% during the
post-vaccine years for which data were evaluated.
Three studies from two Latin American countries
(Brazil and Mexico) have reported a decline of 22-41%
in gastroenteritis mortality among children younger than
five years of age in post-vaccine years; this corresponds
with annual absolute reductions of ~700 infant gastroen-
teritis deaths in Mexico and ~1,300 infant gastroenteritis
deaths in Brazil (Richardson et al. 2010, do Carmo et al.
2011, Lanzieri et al. 2011).
Five studies from four Latin American countries
(Brazil, El Salvador, Mexico and Panama) have reported
a decline of 17% to 51% in all cause gastroenteritis-as-
sociated hospitalizations among children younger than
five years of age in post-vaccine years (de Palma et al.
2010, Lanzieri et al. 2010, do Carmo et al. 2011, Molto et
al. 2011, Quintanar-Solares et al. 2011). Two studies from
two Latin American countries (Brazil, El Salvador) have
reported a decline of 59% to 81% in laboratory-con-
firmed RVA hospitalizations among children younger
than five years of age in post-vaccine years (Sáfadi et al.
2010, Yen et al. 2011a).
Case-control evaluations of vaccine effectiveness
- Case-control studies from Latin American settings
were done in one lower income country (Nicaragua) and
three middle income countries (El Salvador, Brazil and
Mexico) (Table II). In Nicaragua, the vaccine efficacy
for averting RVA gastroenteritis hospitalization was
46% for the full schedule of RV5 and 52% for the partial
vaccine schedule (Patel et al. 2009). In the three middle
income countries, the vaccine efficacy for averting RVA
gastroenteritis hospitalization was 76-94% for the full
schedule of RV1 (Gurgel et al. 2007, Correia et al. 2010,
de Palma et al. 2010, Justino et al. 2011, Yen et al. 2011b)
and 51-84% for the partial vaccine schedule (de Palma et
al. 2010, Yen et al. 2011b). In Nicaragua and Brazil, the
most prevalent RVA genogroup identified among cases
was G2P(4) (Gurgel et al. 2007, Patel et al. 2009, Correia
et al. 2010, Justino et al. 2011), in El Salvador the most
prevalent RVA genogroup identified among cases was
National estimates of reduction in all-cause diarrhoea and species A rotavirus (RVA)
disease burden after RVA vaccine introduction
Decline in disease
Children under five
years of age
Richardson et al. (2010)
Lanzieri et al. (2010)
do Carmo et al. (2011)
do Carmo et al. (2011)
Lanzieri et al. (2010)
Molto et al. (2011)
Quintanar-Solares et al. (2011)
de Palma et al. (2010)a
Yen et al. (2011a)
Sáfadi et al. (2010)
a: Jan-June estimates; b: children under one or two years of age depending on year of vaccine introduction; c: annual average over
the post-vaccine; d: RVA dose 2 coverage years.
Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 106(8), December 2011
G1P(8) (de Palma et al. 2010) and in Mexico the most
prevalent RVA genogroup identified among cases was
G9P(4) (Yen et al. 2011b).
Since RVA vaccine introduction, significant and sus-
tained declines in gastroenteritis disease burden have
been documented in multiple Latin America settings,
illustrating the health benefits of RVA vaccines. Of par-
ticular note, reductions in gastroenteritis mortality, an
outcome that was not evaluated in clinical trials, were
documented in the two largest countries of the region
that have introduced RVA vaccine (Brazil and Mexico),
underscoring the life-saving potential of these vaccines.
Furthermore, the drastic reduction in gastroenteritis
deaths confirms pre-vaccine estimates of RVA-attribut-
able mortality which had been questioned because they
were based upon the assumption that the proportion of
deaths due to RVA equates that proportion of hospital-
izations due to RVA. In addition to mortality benefits,
large reductions in gastroenteritis-associated hospital-
izations and RVA hospitalizations were observed, which
has important implications for reductions in health care
utilization costs. The observed reductions were among
children under five years of age and included only one or
two vaccinated birth cohorts. Interestingly, studies from
the US have found reductions in RVA among older chil-
dren ineligible for vaccine, suggesting the possibility of
indirect benefits from a herd immunity effect (Lopman
et al. 2011). As the vaccine program continues through-
out the Latin American region, a larger proportion of
children under five years of age will have been vaccine
eligible as infants and the real-world direct and indirect
vaccine impact may become even more dramatic.
The field effectiveness of RV1 in Brazil and El Sal-
vador was comparable to the overall 85% efficacy ob-
served in the pivotal pre-licensure trial of RV1 in 11
Latin American countries. Interestingly, RV5 effective-
ness in Nicaragua, the only low income Latin American
country with available data, was lower and was simi-
lar to that seen in African and Asian settings. This di-
chotomy suggests that factors related to income (e.g.,
concurrent enteric infections, malnutrition) may, in part,
explain the differences in vaccine efficacy by setting.
Of note, however, the efficacy of RV1 in a poor region
of Mexico during a G9P(4) outbreak was comparable to
that in other middle income settings. Further evaluations
of effectiveness of both RVA vaccines in impoverished
Latin American settings, such as in Bolivia, which intro-
duced vaccine in 2008, are needed to help assess the full
significance of these observations.
Given the year-to-year and regional variability in
RVA strain prevalence, interpreting RVA genotype epi-
demiology after RVA vaccine introduction is particularly
challenging and underscores the importance of ongo-
ing monitoring of vaccine effectiveness against a broad
range of serotypes (Jiang et al. 2010). A predominance in
G2P(4) RVA strains was observed in Nicaragua and Bra-
zil after the introduction of RV5 and RV1, respectively
(Gurgel et al. 2007, Patel et al. 2009, Correia et al. 2010,
Justino et al. 2011). Because this strain differs from the
RV1 vaccine strain by G-type, P-type and genogroup and
also from the RV5 vaccine strain which contains the G2
reassortant, but not the P(4) reassortant, monitoring of
G2P(4) is of particular interest after the introduction of
vaccine. However, several observations from the stud-
ies in Latin America suggest that this predominance was
likely due to secular variation and unrelated to vaccine
pressure. First, the effectiveness of both vaccines against
G2P(4) was similar to that against other G and P-type
strains in the clinical trials from similar income settings.
Second, although G2P(4) was the predominant strain in
Brazil in the first year after RVA vaccine introduction,
it was soon replaced by non-G2 strains in subsequent
years (Carvalho-Costa et al. 2011). Third, in El Salvador,
a G2P(4) predominance occurred in the year before vac-
cine introduction, but G1P(8) became the dominant strain
after vaccine introduction (de Palma et al. 2010). Last-
ly, in the short term there is no evidence of widespread
emergence of a vaccine-resistant strain of RVA. Thus, it
would be prudent to interpret the changing ecology of
RVA strains after vaccine in the context of vaccine effec-
tiveness studies or changes in absolute disease burden.
This assessment of RVA vaccine impact in Latin
American settings was limited by variation in meth-
odology used between studies. Studies that examined
Case-control studies evaluating full vaccine schedule and partial vaccine
schedule vaccine efficacy against species A rotavirus hospitalizationa
Patel et al. (2009)
de Palma et al. (2010)
Gurgel et al. (2007)
Justino et al. (2011)
Correia et al. (2010)
Yen et al. (2011b)
a: most infants included in the analysis of partial vaccine schedule are between vaccine doses; b: among six-11 months old infants.
Species RVA vaccine in Latin America • Rishi Desai et al.
time-trends used variable pre and post-vaccine year(s),
with country specific differences in vaccine introduced,
introduction date and vaccine coverage rates. Although
most studies assessed the vaccine impact for children
younger than five years of age using annual rates, one
study presented vaccine impact for just the RVA season
(de Palma et al. 2010), which would likely overestimate
the rate reduction. Our assessment includes studies from
a lower-middle income and upper-middle income coun-
tries; however, local factors (e.g. health care access, vac-
cine coverage rates, RVA epidemiology) make it diffi-
cult to tease out the effect, if any, of income per capita.
Among case-control studies, case definitions of RVA dis-
ease were based upon laboratory testing, however, con-
trol groups varied between children with RVA-negative
gastroenteritis, acute respiratory infections, as well as
healthy children in the community. These control groups
are meant to reflect the source populations from which
the cases arose and the use of different groups between
studies makes comparisons challenging. Finally, most of
the data for effectiveness of partial schedule was based
on cases between doses and thus effectiveness close to
vaccination that should be interpreted with caution.
In conclusion, data generated from countries in Latin
America that have introduced RVA vaccine provide evi-
dence of substantial reductions in both diarrhoea deaths
and hospitalizations among children. These documented
benefits of vaccination have been compared with the
small risk of vaccine-associated intussusception identi-
fied in post-licensure trials and World Health Organiza-
tion and other regulatory agencies have affirmed that the
vaccine benefits outweigh the risks (Jiang et al. 2010).
For example, in Brazil and Mexico combined, RVA
vaccine has been estimated to cause 150 excess annual
intussusception cases, but has also prevented approxi-
mately 140,000 diarrhoea hospitalizations and 1,300 di-
arrhoea deaths annually among children under five years
of age. Furthermore, because vaccine benefits have been
documented in both developing and developed countries
of Latin America, they highlight the value of RVA vac-
cines in improving child in all regions of the world. In
countries of Asia and Africa where more than 85% of
RVA deaths occur, widespread use of RVA vaccines is
anticipated in the next one-two years with funding sup-
port through the GAVI Alliance (2011). Given the suc-
cessful experience of RVA vaccines in Latin America,
the global use of RVA vaccines could have a substantial
impact on diarrhoeal morbidity and mortality and thus
will accelerate reaching the fourth Millennium Develop-
ment Goal of reduced child mortality.
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