Live attenuated human rotavirus vaccine, RIX4414, provides clinical protection in infants against rotavirus strains with and without shared G and P genotypes: integrated analysis of randomized controlled trials

Vaccines for preventing rotavirus diarrhoea: vaccines in use

BACKGROUND

Rotavirus results in higher diarrhoea-related death in children less than five years of age than any other single agent, particularly in low- and middle-income countries. The World Health Organization has recommended the use of rotavirus vaccines in childhood immunization schedules.

OBJECTIVES

To evaluate rotavirus vaccines approved for use (Rotarix, RotaTeq, and Lanzhou Lamb Rotavirus (LLR)) for preventing rotavirus diarrhoea.

SEARCH STRATEGY

In February 2010, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (published in The Cochrane Library 2009, Issue 1), MEDLINE, EMBASE, LILACS, and BIOSIS. We also searched the ICTRP (January 2010) and checked reference lists of identified studies.

SELECTION CRITERIA

Randomized controlled trials comparing rotavirus vaccines approved for use with placebo, no intervention, or another vaccine in children.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial eligibility, extracted data, and assessed risk of bias. Dichotomous data were combined using the risk ratio (RR) and 95% confidence intervals (CI).

MAIN RESULTS

Thirty-four trials that included 175,944 participants met the inclusion criteria. They evaluated Rotarix (26 trials; 99,841 participants) and RotaTeq (eight trials; 76,103 participants), and had variable risk of bias (where information provided). None of the identified trials used LLR or compared rotavirus vaccines. Compared to placebo, Rotarix and RotaTeq were both effective at reducing rotavirus diarrhoea (severe cases and cases of any severity). They also reduced all-cause diarrhoea (severe cases), and hospitalizations and need for medical attention caused by rotavirus diarrhoea. However, few data were available for Rotarix and all-cause diarrhoea. Versus the placebo groups, participants in each vaccine group had similar numbers of deaths, serious adverse events, reactogenicity profiles (fever, diarrhoea, and vomiting), and adverse events that required discontinuation of the vaccination schedule. Both vaccines were immunogenic (measured by virus shedding in stool and/or seroconversion). Subgroup analyses indicate that both vaccines are effective in countries with different incomes, but few data are available.

AUTHORS' CONCLUSIONS

Rotarix and RotaTeq are effective vaccines for the prevention of rotavirus diarrhoea. The balance between benefit and harm favours benefit. Ongoing safety monitoring should be continued. Trials comparing LLR with placebo should be conducted and the results made available.

Universal mass vaccination against rotavirus gastroenteritis: impact on hospitalization rates in austrian children

BACKGROUND

Since July 2007, rotavirus vaccinations have been subsidized in Austria for all children from the seventh week up to the sixth month of life. Vaccination coverage over the whole period was 72% with an increase to 87% in 2008.

METHODS

In a sentinel network including 11 pediatric hospital wards in Austria, data of children up to 15 years of age and hospitalized due to rotavirus gastroenteritis between January 2001 and December 2008 have been collected.

RESULTS

The hospitalization rates of children up to 12 months of age with rotavirus gastroenteritis were 2066 x 10(-5) between 2001 and 2006 and decreased to 631 x 10(-5) in 2008. For children between 12 and 24 months of age the hospitalization rate decreased from 1822 x 10(-5) (2001-2006) to 1456 x 10(-5) in 2008. In children aged 2 to less than 5 years, incidence rates were 436 x10(-5) (2001-2006) and 461 x 10(-5) in 2008. In older children, the hospitalization rates remained unchanged. In the target population for the RV-vaccine, a decrease of hospitalization rates due to rotavirus gastroenteritis of 74% was observed compared to the era before the introduction of the vaccine. The field effectiveness of the vaccine was estimated between 61% and 98%, depending on assumptions about the vaccination status.

CONCLUSIONS

Within 18 months, the universal mass vaccination program against rotavirus led to a substantial decrease in the hospitalization rates of the target cohort of the immunization program in Austria.

Effect of human rotavirus vaccine on severe diarrhea in African infants

BACKGROUND

Rotavirus is the most common cause of severe gastroenteritis among young children worldwide. Data are needed to assess the efficacy of the rotavirus vaccine in African children.

METHODS

We conducted a randomized, placebo-controlled, multicenter trial in South Africa (3166 infants; 64.1% of the total) and Malawi (1773 infants; 35.9% of the total) to evaluate the efficacy of a live, oral rotavirus vaccine in preventing severe rotavirus gastroenteritis. Healthy infants were randomly assigned in a 1:1:1 ratio to receive two doses of vaccine (in addition to one dose of placebo) or three doses of vaccine--the pooled vaccine group--or three doses of placebo at 6, 10, and 14 weeks of age. Episodes of gastroenteritis caused by wild-type rotavirus during the first year of life were assessed through active follow-up surveillance and were graded with the use of the Vesikari scale.

RESULTS

A total of 4939 infants were enrolled and randomly assigned to one of the three groups; 1647 infants received two doses of the vaccine, 1651 infants received three doses of the vaccine, and 1641 received placebo. Of the 4417 infants included in the per-protocol efficacy analysis, severe rotavirus gastroenteritis occurred in 4.9% of the infants in the placebo group and in 1.9% of those in the pooled vaccine group (vaccine efficacy, 61.2%; 95% confidence interval, 44.0 to 73.2). Vaccine efficacy was lower in Malawi than in South Africa (49.4% vs. 76.9%); however, the number of episodes of severe rotavirus gastroenteritis that were prevented was greater in Malawi than in South Africa (6.7 vs. 4.2 cases prevented per 100 infants vaccinated per year). Efficacy against all-cause severe gastroenteritis was 30.2%. At least one serious adverse event was reported in 9.7% of the infants in the pooled vaccine group and in 11.5% of the infants in the placebo group.

CONCLUSIONS

Human rotavirus vaccine significantly reduced the incidence of severe rotavirus gastroenteritis among African infants during the first year of life. (ClinicalTrials.gov number, NCT00241644.)

A mathematical model of the indirect effects of rotavirus vaccination

Rotavirus (RV) infections progressively confer natural immunity against subsequent infection. Similarly to natural infection, vaccination with a live attenuated vaccine potentially reduces RV transmission and induces herd protection. A mathematical transmission model was developed to project the impact of a vaccination programme on the incidence of RV infection and disease for five countries in the European Union. With vaccination coverage rates of 70%, 90% and 95% the model predicted that, in addition to the direct effect of vaccination, herd protection induced a reduction in RV-related gastroenteritis (GE) incidence of 25%, 22% and 20%, respectively, for RV-GE of any severity, and of 19%, 15%, and 13%, respectively, for moderate-to-severe RV-GE, 5 years after implementation of a vaccination programme.

A critical review on a globally-licensed, live, orally-administrable, monovalent human rotavirus vaccine: Rotarix

Rotavirus is the major cause of severe gastroenteritis in children worldwide, and two, live, orally-administrable vaccines are licensed globally. They are Rotarix, a monovalent, human rotavirus-based vaccine (GlaxoSmithKline), and RotaTeq, a pentavalent, bovine-human reassortant vaccine (Merck). The RIX4414 strain, a G1P[8] virus, is contained in the Rotarix vaccine. It grows efficiently in the human intestine, as evidenced by vaccine virus shedding into faeces. Efficient multiplication of RIX4414 in the intestines may play a role in stimulating immune effectors other than neutralizing antibodies that may explain the protective immunity against fully heterotypic G2P[4] strains. The protective efficacy against severe rotavirus gastroenteritis afforded by Rotarix is consistently better against strains that share with RIX4414 both G and P serotypes (i.e., G1P[8]), or only P serotype (i.e., G3P[8], G4P[8] and G9P[8]). The Rotarix vaccine is safe regarding intussusception if its first dose is administered between 6 and 12 weeks of age and the last dose by 24 weeks of age with a minimum interval of 4 weeks between the two doses. The expansion by Advisory Committee on Immunization Practices, USA, of the age limit for the first dose to age <15 weeks, and the last dose by 8 months requires close monitoring.

Public health impact and cost effectiveness of mass vaccination with live attenuated human rotavirus vaccine (RIX4414) in India: model based analysis

OBJECTIVES

To examine the public health impact of mass vaccination with live attenuated human rotavirus vaccine (RIX4414) in a birth cohort in India, and to estimate the cost effectiveness and affordability of such a programme.

DESIGN

Decision analytical Markov model encompassing all direct medical costs. Infection risk and severity depended on age, number of previous infections, and vaccination history; probabilities of use of inpatient and outpatient health services depended on symptom severity.

DATA SOURCES

Published clinical, epidemiological, and economic data. When possible, parameter estimates were based on data specific for India. Population Simulated Indian birth cohort followed for five years.

MAIN OUTCOME MEASURES

Decrease in rotavirus gastroenteritis episodes (non-severe and severe), deaths, outpatient visits, and admission to hospital; incremental cost effectiveness ratio of vaccination expressed as net cost in 2007 rupees per life year saved.

RESULTS

In the base case, vaccination prevented 28,943 (29.7%) symptomatic episodes, 6981 (38.2%) severe episodes, 164 deaths (41.0%), 7178 (33.3%) outpatient visits, and 812 (34.3%) admissions to hospital per 100,000 children. Vaccination cost 8023 rupees (about pound100, euro113, $165) per life year saved, less than India's per capita gross domestic product, a common criterion for cost effectiveness. The net programme cost would be equivalent to 11.6% of the 2006-7 budget of the Indian Department of Health and Family Welfare. Model results were most sensitive to variations in access to outpatient care for those with severe symptoms. If this parameter was increased to its upper limit, the incremental cost effectiveness ratio for vaccination still fell between one and three times the per capita gross domestic product, meeting the World Health Organization's criterion for "cost effective" interventions. Uncertainty analysis indicated a 94.7% probability that vaccination would be cost effective according to a criterion of one times per capita gross domestic product per life year saved, and a 97.8% probability that it would be cost effective according to a criterion of three times per capita gross domestic product.

CONCLUSIONS

Across a wide range of assumptions, mass RIX4414 vaccination in India would probably prevent substantial morbidity and mortality at a cost per life year saved below typical thresholds of cost effectiveness. The opportunity costs of such a programme in this or similar settings, however, should be weighed up carefully.