Catherine Yen

Decline in Diarrhea Mortality and Admissions after Routine Childhood Rotavirus Immunization in Brazil: A Time-Series Analysis

A time series analysis by Manish Patel and colleagues shows that the introduction of rotavirus vaccination in Brazil is associated with reduced diarrhea-related deaths and hospital admissions in children under 5 years of age.

Uptake, impact, and effectiveness of rotavirus vaccination in the United States: review of the first 3 years of postlicensure data.

Background: Rotavirus vaccine was recommended for routine use in US infants in 2006. Before the introduction of vaccine, rotavirus was the most common cause of severe gastroenteritis in children <5 years of age in the United States. Methods: We reviewed published data to summarize the US experience during the first 3 years of its rotavirus vaccination program. Results: Rotavirus seasons have been delayed and diminished in magnitude during the postvaccine era compared with the prevaccine era. Hospitalizations, emergency department visits, and outpatient visits due to gastroenteritis have declined dramatically in children <5 years of age including in children age-ineligible to have received vaccine, suggesting indirect benefits of vaccination. Rotavirus vaccine has been widely accepted by pediatricians. Vaccine coverage is steadily increasing but remains lower than coverage levels of other routine infant immunizations. Conclusions: The implementation of routine childhood immunization against rotavirus has rapidly and dramatically reduced the large health burden of rotavirus gastroenteritis in US children. Continued monitoring of rotavirus diarrhea is needed to determine if immunity wanes as vaccinated children get older and to better quantify the indirect benefits of vaccination. Ongoing surveillance will also enable monitoring of the long-term impact of vaccination on rotavirus epidemiology.

Sustained decline in rotavirus detections in the United States following the introduction of rotavirus vaccine in 2006.

Background: Following implementation of the rotavirus vaccination program in 2006, rotavirus activity in the United States declined dramatically in 2007–2008 but increased slightly in 2008–2009, despite greater vaccine uptake. To further evaluate impact of the vaccine program, we assessed trends in rotavirus testing and detection during 2009–2010. Methods: We examined rotavirus testing data from July 2000 to June 2010 from the National Respiratory and Enteric Viruses Surveillance System to compare rotavirus season timing and peak activity in the pre- and postvaccine introduction eras. Rotavirus season onset was defined as the first of 2 consecutive weeks during which the percentage of specimens testing positive for rotavirus was ≥10%. To assess trends in rotavirus testing and detection, we restricted the analyses to 25 laboratories that reported for ≥26 weeks per season from 2000 to 2010. Results: During 2009–2010, the threshold for the start of the rotavirus season was never achieved nationally or in the North, Midwest, or West. Activity in the South met this threshold but the season duration was substantially shorter and of lower magnitude than in all previous pre- and postvaccine introduction seasons. Nationally and within each region, the peak week was more delayed and the peak proportion of positive tests was substantially lower than all previous seasons. The total number of tests performed declined by 23%, and the number of positive tests declined by 86%. Conclusions: Rotavirus activity was substantially diminished during the 2009–2010 rotavirus season compared with the prevaccine baseline and the 2 previous postvaccine introduction seasons. These sustained declines over 3 rotavirus seasons reaffirm the health benefits of the US rotavirus vaccination program.

Impact of an Emergent Norovirus Variant in 2009 on Norovirus Outbreak Activity in the United States

In October 2009, a new genogroup II, type 4 (GII.4) norovirus variant was identified in the United States. We collected norovirus outbreak data from 30 states to assess whether this new strain was associated with increased acute gastroenteritis activity. No increase in norovirus outbreaks was observed during the 2009-2010 winter.

Diarrhea-Associated Hospitalizations Among US Children Over 2 Rotavirus Seasons After Vaccine Introduction

OBJECTIVE: After implementation of rotavirus vaccination in 2006, large decreases in rates of severe diarrhea among US children occurred in 2007–2008. We ascertained whether these decreases were sustained in 2008–2009. METHODS: We examined hospital discharge data from a national network of pediatric hospitals and compared all-cause diarrhea-related and rotavirus-specific hospitalizations in 3 prevaccine rotavirus seasons (2003–2006) with those in 2 postvaccine seasons (2007–2008 and 2008–2009) among children <5 years of age. We defined rotavirus seasons using data from a national laboratory surveillance network. RESULTS: At 62 consistently reporting hospitals, a median of 15 645 diarrhea-related hospitalizations (range: 14 881–16 884 hospitalizations) occurred each rotavirus season among children <5 years of age in 2003–2006. Compared with this median, all-cause diarrhea-related hospitalizations decreased by 50% (n = 7760) in 2007–2008 and by 29% (n = 11 039) in 2008–2009. In 2007–2008, reductions of 47% to 55% were seen for all age groups, including vaccine-ineligible children ≥2 years of age (48%). In 2008–2009, these reductions decreased in magnitude, especially among children ≥2 years of age (17%). Decreases in 2007–2008 and 2008–2009 were similar in the Northeast and West, but decreases were smaller in 2008–2009, compared with 2007–2008, in the Midwest and South. CONCLUSIONS: Compared with prevaccine seasons, decreases in diarrhea- and rotavirus-associated hospitalizations seen in 2007–2008 were sustained in 2008–2009 but were somewhat smaller. Given the variability in diarrhea-related hospitalization trends over the 2 postvaccine seasons according to age group and region, continued surveillance is required for full assessment of the impact of rotavirus vaccination.

Rotavirus vaccines: current status and future considerations.

Rotavirus is the leading cause of severe diarrhea among children <5 years worldwide. Currently licensed rotavirus vaccines have been efficacious and effective, with many countries reporting substantial declines in diarrheal and rotavirus-specific morbidity and mortality. However, the full public health impact of these vaccines has not been realized. Most countries, including those with the highest disease burden, have not yet introduced rotavirus vaccines into their national immunization programs. Research activities that may help inform vaccine introduction decisions include (1) establishing effectiveness, impact, and safety for rotavirus vaccines in low-income settings; (2) identifying potential strategies to improve performance of oral rotavirus vaccines in developing countries, such as zinc supplementation; and (3) pursuing alternate approaches to oral vaccines, such as parenteral immunization. Policy- and program-level barriers, such as financial implications of new vaccine introductions, should be addressed to ensure that countries are able to make informed decisions regarding rotavirus vaccine introduction.

Potential intussusception risk versus benefits of rotavirus vaccination in the United States.

Background: International data show a low-level increased risk of intussusception associated with rotavirus vaccination. Although US data have not documented a risk, we assumed a risk similar to international settings and compared potential vaccine-associated intussusception cases with benefits of prevention of rotavirus gastroenteritis by a fully implemented US rotavirus vaccine program. Methods: To calculate excess intussusception cases, we used national data on vaccine coverage and baseline intussusception rates, and assumed a vaccine-associated intussusception relative risk of 5.3 (95% confidence interval [CI]: 3.0–9.3) in the first week after the first vaccine dose, the risk seen in international settings. We used postlicensure vaccine effectiveness data to calculate rotavirus disease burden averted. Results: For a US birth cohort of 4.3 million infants, vaccine-associated intussusception could cause an excess 0.2 (range: 0.1–0.3) deaths, 45 (range: 21–86) hospitalizations and 13 (range: 6–25) cases managed in short-stay or emergency department settings. Vaccination would avert 14 (95% CI: 10–19) rotavirus-associated deaths, 53,444 (95% CI: 37,622–72,882) hospitalizations and 169,949 (95% CI: 118,161–238,630) emergency department visits. Summary benefit–risk ratios for death and hospitalization are 71:1 and 1093:1, respectively. Conclusions: The burden of severe rotavirus disease averted due to vaccination compared with the vaccine-associated intussusception events offers a side-by-side analysis of the benefits and potential risks. If an intussusception risk similar to that seen internationally exists in the United States, it is substantially exceeded by the benefits of rotavirus disease burden averted by vaccination.

Rotavirus vaccines: Update on global impact and future priorities

Early rotavirus vaccine adopter countries in the Americas, Europe, and in Australia have documented substantial declines in rotavirus disease burden following the introduction of vaccination. However, the full public health impact of rotavirus vaccines has not been realized as they have not been introduced into routine immunization programs in countries of Africa and Asia with the highest rotavirus disease morbidity and mortality burden. In this article, we review the epidemiology of rotavirus disease, the development and current status of rotavirus vaccines including newly available vaccine impact data from early-introducer countries, and future priorities for implementation and monitoring of rotavirus vaccination programs in developing countries.

Global Impact of Rotavirus Vaccination on Childhood Hospitalizations and Mortality From Diarrhea

In 2006, 2 rotavirus vaccines were licensed. We summarize the impact of rotavirus vaccination on hospitalizations and deaths from rotavirus and all-cause acute gastroenteritis (AGE) during the first 10 years since vaccine licensure, including recent evidence from countries with high child mortality. We used standardized guidelines (PRISMA) to identify observational evaluations of rotavirus vaccine impact among children <5 years of age that presented at least 12 months of pre- and post-vaccine introduction surveillance data. We identified 57 articles from 27 countries. Among children <5 years of age, the median percentage reduction in AGE hospitalizations was 38% overall and 41%, 30%, and 46% in countries with low, medium, and high child mortality, respectively. Hospitalizations and emergency department visits due to rotavirus AGE were reduced by a median of 67% overall and 71%, 59%, and 60% in countries with low, medium, and high child mortality, respectively. Implementation of rotavirus vaccines has substantially decreased hospitalizations from rotavirus and all-cause AGE.

Effectiveness of Rotavirus Vaccination: A Systematic Review of the First Decade of Global Postlicensure Data, 2006–2016

Two rotavirus vaccines, Rotarix (RV1) and RotaTeq (RV5), were licensed for global use in 2006. A systematic review of 48 peer- reviewed articles with postlicensure data from 24 countries showed a median RV1 vaccine effectiveness (VE) of 84%, 75%, and 57% in countries with low, medium, and high child mortality, respectively, and RV5 VE of 90% and 45% in countries with low and high child mortality, respectively. A partial vaccine series provided considerable protection, but not to the same level as a full series. VE tended to decline in the second year of life, particularly in medium- and high-mortality settings, and tended to be greater against more severe rotavirus disease. Postlicensure data from countries across geographic regions and with different child mortality levels demonstrate that under routine use, both RV1 and RV5 are effective against rotavirus disease, supporting the World Health Organization recommendation that all countries introduce rotavirus vaccine into their national immunization program.