Rotavirus vaccination takes seasonal signature of childhood diarrhea back to pre-sanitation era in Brazil

Abstract

Objectives: This study aimed to examine the previously unknown long-term spatio-temporal patterns in diarrheal morbidity and mortality across age groups and geography in Brazil under the light of evolving socioeconomic factors and interventions.

Methods: Nationwide mortality (1979-2014) and hospitalization (1998-2014) data were obtained from the Brazilian Ministry of Health. Analyses of long-term secular trends and seasonality of diarrheal morbidity and mortality were performed in EPIPOI (www.epipoi.info).

Results: For most states, the primary peak in mortality risk among children under 5 years occurred from December-April (summer/early autumn) from 1979-1988. From 2000-2005 (before the 2006 implementation of rotavirus vaccination), the pattern switched to June-October (winter/early spring). By 2007-2014, the peak in mortality shifted back towards summer/early autumn. A similar pattern was observed for hospitalizations. These patterns were particularly apparent in non-equatorial regions of the country. In contrast, the risk of diarrhea-related death among older children (5-19 years) did not demonstrate well-defined seasonality or spatial patterns.

Conclusions: Rotavirus vaccination policies were associated with a shift in the timing of seasonal peaks in children under 5, reminiscent of the summer diarrhea period common decades prior. Additionally, young children were shown to have distinct disease patterns compared to other age groups, suggesting different etiologies.

Keywords: Brazil; Diarrhea; Hospitalization; Interrupted time-series analysis; Mortality; Seasonal variation; Spatio-temporal analysis.

Figure 1

Map of 26 administrative states plus the Capital District ("DF"). The location of each capital is represented by circles, where the size of the symbol is proportionate to the population size of each state (log10 scale). The colors refer to the five Brazilian administrative regions: North (green), Northeast (yellow), Central West (red), Southeast (dark blue), and South (light blue)

Figure 2

Monthly diarrhea deaths. (A) Risk by state per 100,000 children under 5, sorted by the latitude of their capitals (The state of Tocantins is included beginning in 1988, the year of its secession from the state of Goiás) (B) Risk per 100,000 children under 5 (C) Proportions of deaths per age group (D) Trend of risk of death per 100,000 children under 5.

Figure 3

Monthly diarrhea hospitalizations. (A) Risk by state per 100,000 children under 5, sorted by the latitude of their capitals (B) Risk per 100,000 children under 5 (C) Proportions of hospitalizations per age group (D) Trend of risk of hospitalization per 100,000 children under 5.

Figure 4

Average risk per 100,000 and the linear trend of hospitalizations in children under 5 caused by diarrhea in Brazil per state for the period 2007–2014. Colors represent the different regions of Brazil (see map in Figure 1).

Figure 5

Primary peak in risk of diarrheal mortality (first row) and hospitalizations (second row) per 100,000 children under 5 years in Brazil by state for three periods: "Transition period" (1979 to 1988), "Modern pre-rotavirus vaccine period" (2000 to 2005) and "Modern post-rotavirus vaccine period" (2007 to 2014). The size of circles are proportional to the amplitude of the seasonality. Colors represent the different regions of Brazil (see map in Figure 1).