Impact of Rotavirus Vaccination Varies by Level of Access to Piped Water and Sewerage: An Analysis of Childhood Clinic Visits for Diarrhea in Peru, 2005-2015

Impact of rotavirus vaccination on diarrheal disease burden of children in South America

INTRODUCTION

Rotavirus is a leading cause of severe diarrheal disease and death in children under five years of age worldwide. Vaccination is one of the most important public health interventions to reduce this significant burden.

AREAS COVERED

This literature review examined vaccination coverage, hospitalization rate, mortality, genotypic distribution, immunogenicity, cost-effectiveness, and risk versus benefit of rotavirus vaccination in children in South America. Nine out of twelve countries in South America currently include a rotavirus vaccine in their national immunization program with coverage rates in 2022 above 90%.

EXPERT OPINION

Introduction of the rotavirus vaccination has led to a marked reduction in hospitalizations and deaths from diarrheal diseases in children under 5 years, particularly infants under 1 year, in several South American countries. In Brazil, hospitalizations decreased by 59% and deaths by 21% (30-38% in infants). In Peru, hospitalizations in infants fell by 46% and deaths by 37% (56% in infants). Overall, data suggest that rotavirus vaccination has reduced rotavirus deaths by 15-50% in various South American countries. There is some evidence that immunity wanes after the age of 1-year old. Ongoing surveillance of vaccine coverage and changes in morbidity and mortality is important to maximize protection against this disease.

Exploring Survey-Based Water, Sanitation, and Animal Associations With Enteric Pathogen Carriage: Comparing Results in a Cohort of Cases With Moderate-to-Severe Diarrhea to Those in Controls in the Vaccine Impact on Diarrhea in Africa (VIDA) Study, 2015-2018

BACKGROUND

The magnitude of pediatric enteric pathogen exposures in low-income settings necessitates substantive water and sanitation interventions, including animal feces management. We assessed associations between pediatric enteric pathogen detection and survey-based water, sanitation, and animal characteristics within the Vaccine Impact on Diarrhea in Africa case-control study.

METHODS

In The Gambia, Kenya, and Mali, we assessed enteric pathogens in stool of children aged <5 years with moderate-to-severe diarrhea and their matched controls (diarrhea-free in prior 7 days) via the TaqMan Array Card and surveyed caregivers about household drinking water and sanitation conditions and animals living in the compound. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated using modified Poisson regression models, stratified for cases and controls and adjusted for age, sex, site, and demographics.

RESULTS

Bacterial (cases, 93%; controls, 72%), viral (63%, 56%), and protozoal (50%, 38%) pathogens were commonly detected (cycle threshold <35) in the 4840 cases and 6213 controls. In cases, unimproved sanitation (RR, 1.56; 95% CI, 1.12-2.17), as well as cows (RR, 1.61; 95% CI, 1.16-2.24) and sheep (RR, 1.48; 95% CI, 1.11-1.96) living in the compound, were associated with Shiga toxin-producing Escherichia coli. In controls, fowl (RR, 1.30; 95% CI, 1.15-1.47) were associated with Campylobacter spp. In controls, surface water sources were associated with Cryptosporidium spp., Shigella spp., heat-stable toxin-producing enterotoxigenic E. coli, and Giardia spp.

CONCLUSIONS

Findings underscore the importance of enteric pathogen exposure risks from animals alongside more broadly recognized water and sanitation risk factors in children.

Predicting the long-term impact of rotavirus vaccination in 112 countries from 2006 to 2034: A transmission modeling analysis

Rotavirus vaccination has been shown to reduce rotavirus burden in many countries, but the long-term magnitude of vaccine impacts is unclear, particularly in low-income countries. We use a transmission model to estimate the long-term impact of rotavirus vaccination on deaths and disability adjusted life years (DALYs) from 2006 to 2034 for 112 low- and middle-income countries. We also explore the predicted effectiveness of a one- vs two- dose series and the relative contribution of direct vs indirect effects to overall impacts. To validate the model, we compare predicted percent reductions in severe rotavirus cases with the percent reduction in rotavirus positivity among gastroenteritis hospital admissions for 10 countries with pre- and post-vaccine introduction data. We estimate that vaccination would reduce deaths from rotavirus by 49.1 % (95 % UI: 46.6-54.3 %) by 2034 under realistic coverage scenarios, compared to a scenario without vaccination. Most of this benefit is due to direct benefit to vaccinated individuals (explaining 69-97 % of the overall impact), but indirect protection also appears to enhance impacts. We find that a one-dose schedule would only be about 57 % as effective as a two-dose schedule 12 years after vaccine introduction. Our model closely reproduced observed reductions in rotavirus positivity in the first few years after vaccine introduction in select countries. Rotavirus vaccination is likely to have a substantial impact on rotavirus gastroenteritis and its mortality burden. To sustain this benefit, the complete series of doses is needed.

Acute Gastroenteritis Morbidity and Mortality Trends Following Universal Rotavirus Vaccination in Children in Peru: Ecological Database Study with Time-Trend Analysis

Introduction

Rotavirus (RV) infection is the leading cause of severe diarrhea in children worldwide. It is responsible for around 25% of gastroenteritis (GE) cases, 33% of hospitalized GE cases, and an annual mortality rate of 113.4/100,000 in children < 5 years of age in Peru. RV infant vaccination is recommended by the World Health Organization and provides the best public health strategy to manage the disease. Universal RV vaccination was introduced in Peru in 2009.

Methods

Trends in GE ambulatory visits, hospitalizations, and deaths in children < 5 years of age are described in the pre-vaccination (2004–2008) versus post-vaccination (2010–2018) periods. Time-trend analysis was performed (using generalized linear regression models) to assess the impact of vaccination nationwide and by region after adjusting for variables.

Results

Between 2009 and 2011, vaccination coverage increased to over 80% in Peru. In infants < 1 year of age, GE ambulatory cases, hospitalizations, and deaths decreased in the post-vaccination period by 40.3%, 46.2%, and 55.5%, respectively (and in children < 5 years of age, by 34.4%, 41.9%, and 54.3%, respectively) compared with the pre-vaccination period. Results of the multivariate time-trend analysis also found significant decreases in the post-vaccination period of 10.7% (GE ambulatory cases), 17.2% (GE hospitalizations), and 37.3% (GE mortality) in children < 5 years of age. Data analyzed by region varied, with Costa and Sierra regions generally in line with the national findings; however, some findings were less robust for Selva due to fewer available data.

Conclusion

After 9 years of RV vaccination in Peru, there appears to be a statistically significant positive impact of vaccination, in terms of reducing GE-related mortality, hospitalizations, and ambulatory visits in infants and young children. For policymakers to understand regional differences and future vaccination needs, continued improvement in surveillance is needed.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00532-5.

Meteorological factors and childhood diarrhea in Peru, 2005-2015: a time series analysis of historic associations, with implications for climate change

BACKGROUND

Global temperatures are projected to rise by ≥2 °C by the end of the century, with expected impacts on infectious disease incidence. Establishing the historic relationship between temperature and childhood diarrhea is important to inform future vulnerability under projected climate change scenarios.

METHODS

We compiled a national dataset from Peruvian government data sources, including weekly diarrhea surveillance records, annual administered doses of rotavirus vaccination, annual piped water access estimates, and daily temperature estimates. We used generalized estimating equations to quantify the association between ambient temperature and childhood (< 5 years) weekly reported clinic visits for diarrhea from 2005 to 2015 in 194 of 195 Peruvian provinces. We estimated the combined effect of the mean daily high temperature lagged 1, 2, and 3 weeks, in the eras before (2005-2009) and after (2010-2015) widespread rotavirus vaccination in Peru and examined the influence of varying levels of piped water access.

RESULTS

Nationally, an increase of 1 °C in the temperature across the three prior weeks was associated with a 3.8% higher rate of childhood clinic visits for diarrhea [incidence rate ratio (IRR): 1.04, 95% confidence interval (CI): 1.03-1.04]. Controlling for temperature, there was a significantly higher incidence rate of childhood diarrhea clinic visits during moderate/strong El Niño events (IRR: 1.03, 95% CI: 1.01-1.04) and during the dry season (IRR: 1.01, 95% CI: 1.00-1.03). Nationally, there was no evidence that the association between temperature and the childhood diarrhea rate changed between the pre- and post-rotavirus vaccine eras, or that higher levels of access to piped water mitigated the effects of temperature on the childhood diarrhea rate.

CONCLUSIONS

Higher temperatures and intensifying El Niño events that may result from climate change could increase clinic visits for childhood diarrhea in Peru. Findings underscore the importance of considering climate in assessments of childhood diarrhea in Peru and globally, and can inform regional vulnerability assessments and mitigation planning efforts.

Could Water and Sanitation Shortfalls Exacerbate SARS-CoV-2 Transmission Risks?

SARS-CoV-2, the etiologic agent of COVID-19, is shed in stool. SARS coronaviruses have been detected in wastewater during outbreaks in China, Europe, and the United States. In this perspective, we outline the risk fecal shedding poses at locations without safely managed sanitation, as in most of Nigeria where we work. We believe that feco-oral transmission could occur if community transmission becomes high and sustained in densely populated cities without proper sanitation in Nigeria and many other African and Asian settings. In the absence of basic sanitation, or where existing sanitation is not safely managed, groundwater, which is often drawn up from wells and boreholes for drinking and household use, can become contaminated with enteric bacteria and viruses from fecal matter. Endemic and epidemic transmission of multiple feco-oral pathogens via this route continues to be documented in areas without safely managed sanitation, and, therefore, the risk of SARS-CoV-2 transmission needs to be evaluated, tracked, and forestalled in such settings. We suggest that fecal matter from treatment facilities and recovered patients should be carefully and properly disposed. Furthermore, environmental surveillance of SARS-CoV-2 in wastewater and accumulated human waste, as well as efforts to mitigate the virus’ entry into unprotected household water sources, should be a priority part of the COVID-19 response in settings without safely managed sanitation for the duration of the pandemic.