Diarrhea is the leading cause of morbidity and mortality among children under 5 years of age in the developing world (1). Rotavirus is the most common cause of diarrhea-associated hospitalization in this age group (2,3). Globally, diarrhea accounted for 0.6 million deaths and rotavirus for 215,000 deaths among children aged 0–5 years in 2013 (4–7). Consequently, the World Health Organization recommends rotavirus vaccines (RV) for routine immunization in all countries (8). In Mexico, RV contributed to a 38% and 50% of reduction in diarrhea-associated hospitalizations and deaths, respectively (9,10). On the African continent, around 134,700 hospitalizations and 21,000 deaths were prevented in 2016, after implementation of rotavirus vaccine in children (11).

The burden of rotavirus-associated hospitalizations among Mauritanian children has been considered as extremely high, but systematic data are scarce. A recent study focusing on the pre-vaccination era has shown that 22.4% of all hospitalizations and 14.1% of deaths among hospitalized children in Mauritania were caused by diarrhea (12). In 2008, a cross-sectional survey conducted in two districts of Mauritania’s capital Nouakchott found that 23.6% of children aged 0–5 years had diarrhea and 52% of cases were associated with poor hygiene (13). A more recent study indicated that global prevalence of diarrhea disease, in 9 municipalities of Nouakchott city, was 12.8% (ranging from 9.1% in Tevregh zeina to 19.1% in Sebkha), with the majority of cases (51.7%) registered among children aged 0–5 years (14). In 2016, the Global Burden of Diseases study estimated that diarrhea was associated with 10.5% of deaths. Unsafe water, inadequate sanitation, and environmental and occupational risks were associated with 29.6% of total deaths among children aged 0–5 years in Mauritania (15).

Mauritania officially introduced Rotarix vaccine in December 2014 in the entire country with 2 doses for children aged 6 and 10 weeks. In Nouakchott city, the vaccine coverage increased from 6% in 2014, to 51% in 2015, 76% in 2016 and 81.5% in 2017 (14). The objective of this study was to provide further data on the impact of RV introduction on a population level, by using as an indicator the proportion of all childhood hospitalizations with diarrhea before and after the introduction of RV in Nouakchott city.

A total of 34,329 hospitalizations were recorded during the study period, distributed over the four hospitals (Table 2). Of these hospitalizations, 6,552 (19%) were classified as having diarrhea among children aged 0–5 years. In the pre-vaccine period, a total of 3,523/16,952 (20.8%) hospitalizations had diarrhea in <5 year-olds, and after introduction of vaccination, 1,656/10,480 (15.8%), a relative reduction of 24% (Table 3). During the transition period, 1,373/6,897 (19.9%) hospitalizations had diarrhea in <5 year-olds.

As shown in Table 3, the reduction of the proportion of hospitalizations with diarrhea was significantly associated with age groups and period of admission. The most prominent reduction (74%) was observed in 2–5 year-olds. The seasonality in diarrhea-associated hospitalizations was shown in figure 1.

Figure 2 shows that during the observation period, the total number of admissions and the admissions with diarrhea in <5 year-olds reduced steadily. The relative frequency of admissions with diarrhea reduced from 22.4% in the first observation period, to 15.3% in the last period.

After rotavirus vaccine introduction in Mauritania, the proportion of childhood hospitalizations with diarrhea in Nouakchott declined by nearly one-fourth. The high reduction that we reported occurred specifically among children that are eligible to get vaccination and consistent with increasing vaccine coverage. Admissions among children <2 months of age with diarrhea increased in the post-vaccine era but this may be because children in this age group are not yet eligible to receive rotavirus vaccine. The reductions were seen in the 3 month to 5 years age group, which is known to be eligible for vaccination. Collectively, these findings support a role of rotavirus vaccination in the observed declines in childhood diarrhea hospitalizations.

In studies done in South Africa, the RV was associated with a 34% to 57% of reduction in the overall incidence of all cause diarrhea hospitalizations and the highest reduction was observed among children aged less than 1 year (18). In studies done in Mexico, the vaccine was associated with 50% of reduction during post-vaccination period (10). Our findings are consistent with these observations and support the hypothesis that the reduction in all-cause diarrhea associated hospitalization can be attributed partly to the introduction of RV.

In our study, diarrhea was associated with about one fifth of all hospitalizations during pre-vaccine period. This was in line with previously study conducted in two districts of Nouakchott in 2008 which has shown that the prevalence of diarrhea in children aged 0–5 years was 23.6% (ranging from a low of 16.8% in Tevregh zeina to a high of 28.3% in Sebkha) (13). According to other household surveys conducted in Nouakchott city, 50.8% of health care admissions were due to respiratory and diarrhea diseases (19).

Our hospital-based study has several limitations, including quantity (such as missing information) and quality (such as diagnostic errors) of hospital data, as well as limited number of variables that can be analyzed. We identified diarrhea hospitalizations based on admission diagnosis rather than discharge diagnosis which may have resulted in the misclassification of some cases. In addition, rotavirus testing is not routinely performed in Mauritania; we could provide data on rotavirus-specific diarrhea hospitalizations and used all-cause diarrhea associated hospitalization. Other factors such as changes in the socioeconomic status among populations or in quantity and quality of health care services in Nouakchott city, can also contribute to the reduction in annual diarrhea-associated hospitalization, rather than the more accelerated decline that we observed in post-vaccination period. As the data abstracted from all referral hospitals in Nouakchott city, which represent a quarter of the Mauritanian population, results may be may be indicative for hospitalized children in the entire country.

We conclude that rotavirus vaccine introduction likely had a significant impact on and reduced the burden of hospitalizations with diarrhea among children aged 0–5 years in Nouakchott, Mauritania.