Impact of rotavirus vaccine on childhood diarrheal hospitalization after introduction into the South African public immunization program

Whole genome detection of rotavirus mixed infections in human, porcine and bovine samples co-infected with various rotavirus strains collected from sub-Saharan Africa

Group A rotaviruses (RVA) are among the main global causes of severe diarrhea in children under the age of 5years. Strain diversity, mixed infections and untypeable RVA strains are frequently reported in Africa. We analysed rotavirus-positive human stool samples (n=13) obtained from hospitalised children under the age of 5years who presented with acute gastroenteritis at sentinel hospital sites in six African countries, as well as bovine and porcine stool samples (n=1 each), to gain insights into rotavirus diversity and evolution. Polyacrylamide gel electrophoresis (PAGE) analysis and genotyping with G-(VP7) and P-specific (VP4) typing primers suggested that 13 of the 15 samples contained more than 11 segments and/or mixed G/P genotypes. Full-length amplicons for each segment were generated using RVA-specific primers and sequenced using the Ion Torrent and/or Illumina MiSeq next-generation sequencing platforms. Sequencing detected at least one segment in each sample for which duplicate sequences, often having distinct genotypes, existed. This supported and extended the PAGE and RT-PCR genotyping findings that suggested these samples were collected from individuals that had mixed rotavirus infections. The study reports the first porcine (MRC-DPRU1567) and bovine (MRC-DPRU3010) mixed infections. We also report a unique genome segment 9 (VP7), whose G9 genotype belongs to lineage VI and clusters with porcine reference strains. Previously, African G9 strains have all been in lineage III. Furthermore, additional RVA segments isolated from humans have a clear evolutionary relationship with porcine, bovine and ovine rotavirus sequences, indicating relatively recent interspecies transmission and reassortment. Thus, multiple RVA strains from sub-Saharan Africa are infecting mammalian hosts with unpredictable variations in their gene segment combinations. Whole-genome sequence analyses of mixed RVA strains underscore the considerable diversity of rotavirus sequences and genome segment combinations that result from a complex evolutionary history involving multiple host species.

Rapid impact of rotavirus vaccine introduction to the National Immunization plan in southern Israel: comparison between 2 distinct populations

BACKGROUND

Rotavirus vaccines were licensed in Israel in 2007, and in 2011 the pentavalent-vaccine (RV5) was introduced into the Israeli National Immunization plan.

AIM

To determine the effect of rotavirus-vaccines on the incidence of hospital visits due to rotavirus gastroenteritis (RVGE) and all-cause diarrhea in Jewish and Bedouin children <5 year residing in southern Israel.

METHODS

We conducted a population-based, prospective, observational study. Data from 2006 through 2013 were analyzed. Our hospital is the only medical center in the region, enabling age-specific incidences calculation.

RESULTS

In the pre-vaccine period, the overall RVGE hospital visits rates per 1000 in children <12, 12-23 and 24-59 m were 16.1, 18.6 and 1.4 in Jewish children, respectively. The respective rates in Bedouin children were 26.4, 12.5 and 0.7 (P<0.001 for <12 m). Hospitalization rates were higher among Bedouin than among Jewish children (60.0% vs. 39.7%, P<0.001). Vaccine uptake was faster in the Jewish vs. the Bedouin population. In the year following RV5 introduction, RVGE hospital visits rates declined by 82%, 70% (P<0.001 both) and 36% (P=0.092) in Jewish children <12, 12-23 and 24-59 m, respectively. In Bedouin children, the respective RVGE rates declined by 70% (P<0.001), 21% (P=ns) and 14% (P=ns). Throughout the study, RVGE rates declined significantly in children <12, and 12-23 m by 80% and 88% in Jewish children, respectively, and by 62 and 75% in Bedouin children, respectively (P<0.001 for all declines). In children 24-59 m, RVGE rates declined by 46% (P=0.025) in Jewish children, but no reduction was observed in Bedouin children. The dynamics of all-cause diarrhea rates were similar to that of RVGE.

CONCLUSIONS

Significant reductions of RVGE rates were observed, following Rota-vaccine introduction in southern Israel in both Jewish and Bedouin children. However, the impact was faster and more profound in Jewish children, probably related to higher vaccine uptake and possibly to lifestyle differences.

Rotavirus surveillance in urban and rural areas of Niger, April 2010-March 2012

Knowledge of rotavirus epidemiology is necessary to make informed decisions about vaccine introduction and to evaluate vaccine impact. During April 2010–March 2012, rotavirus surveillance was conducted among 9,745 children <5 years of age in 14 hospitals/health centers in Niger, where rotavirus vaccine has not been introduced. Study participants had acute watery diarrhea and moderate to severe dehydration, and 20% of the children were enrolled in a nutrition program. Of the 9,745 children, 30.6% were rotavirus positive. Genotyping of a subset of positive samples showed a variety of genotypes during the first year, although G2P[4] predominated. G12 genotypes, including G12P[8], which has emerged as a predominant strain in western Africa, represented >80% of isolates during the second year. Hospitalization and death rates and severe dehydration among rotavirus case-patients did not differ during the 2 years. The emergence of G12P[8] warrants close attention to the characteristics of associated epidemics and possible prevention measures.

Hospital bed occupancy for rotavirus and all cause acute gastroenteritis in two Finnish hospitals before and after the implementation of the national rotavirus vaccination program with RotaTeq®

Background

Vaccination-impact studies of the live-attenuated pentavalent oral vaccine Rotateq® have demonstrated that the burden of rotavirus gastroenteritis has been reduced significantly after the introduction of RotaTeq® vaccination, but less is known about the benefit of this vaccination on hospital overcrowding.

Methods

As part of an observational surveillance conducted during the RV seasons 2000/2001 to 2011/2012, we analysed hospital discharge data collected retrospectively from two Finnish hospitals (Oulu and Tampere), concerning ICD 10 codes A00-09 (acute gastroenteritis, AGE) and A08.0 (rotaviral acute gastroenteritis RV AGE). We estimated the reduction in the number of beds occupied and analysed the bed occupancy rate, for RV AGE and all cause AGE, among 0–16 year-old children, before and after the implementation of the RV immunisation program.

Results

The rate of bed days occupied for RV AGE was reduced by 86% (95% CI 66%-94%) in Tampere and 79% (95% CI 47%-92%) in Oulu after RV vaccination implementation. For all cause AGE, reduction was 50% (95% CI 29% to 65%) in Tampere and 70% (95% CI 58% to 79%) in Oulu. Results were similar among 0–2 year-old children. This effect was also observed on overcrowding in both hospitals, with a bed occupancy rate for all cause AGE >25% in only 1% of the time in Tampere and 9% in Oulu after the implementation of the immunisation program, compared to 13% and 48% in the pre-vaccination period respectively. After extrapolation to the whole country, the annual number of prevented hospitalizations for all cause AGE in the post-vaccination period in Finland was estimated at 1,646 and 2,303 admissions for 0–2 and 0–16 year-old children respectively.

Conclusions

This study demonstrated that universal RV vaccination is associated with a clear decrease in the number of bed days and occupancy rates for RV AGE and all cause AGE. Positive consequences include increase in quality of care and a better healthcare management during winter epidemics.

Rotavirus vaccines in routine use

Vaccines are now available to combat rotavirus, the most common cause of severe diarrhea among children worldwide. We review clinical trial data for available rotavirus vaccines and summarize postlicensure data on effectiveness, impact, and safety from countries routinely using these vaccines in national programs. In these countries, rotavirus vaccines have reduced all-cause diarrhea and rotavirus hospitalizations by 17%-55% and 49%-92%, respectively, and all-cause diarrhea deaths by 22%-50% in some settings. Indirect protection of children who are age-ineligible for rotavirus vaccine has also been observed in some high and upper middle income countries. Experience with routine use of rotavirus vaccines in lower middle income countries has been limited to date, but vaccine introductions in such countries have been increasing in recent years. The risk-benefit analysis of rotavirus vaccines is extremely favorable but other strategies to improve the effectiveness of the vaccine, particularly in lower middle income settings, should be considered.

Whole-genome analyses reveals the animal origin of a rotavirus G4P[6] detected in a child with severe diarrhea

Group A rotaviruses are a major cause of severe gastroenteritis in children worldwide. Currently, two rotavirus vaccines are being used in vaccination programs, and one of the factors involved in lower vaccine efficacy is the mismatch among the circulating strains and the vaccine strains. Thus, the emergence of animal strains in the human population could affect the efficacy of vaccination programs. Here we report the presence of a G4P[6] strain in a Paraguayan child presenting acute gastroenteritis in 2009. Genomic analyses revealed that the strain presents a porcine-like genome (G4-P[6]-I1-R1-C1-M1-A8-N1-T7-E1-H1), suggesting a direct animal-to-human transmission. Continuous surveillance of rotaviruses in humans and animals will help us to better understand rotavirus epidemiology and evolution.

Molecular characterization of rotavirus strains from pre- and post-vaccination periods in a country with low vaccination coverage: the case of Slovenia

Rotavirus vaccination started in Slovenia in 2007 on a voluntarily basis. The vaccination rate is relatively low (up to 27%) and no increasing trend is observed. We present rotavirus genotype distribution among children hospitalized for rotavirus gastroenteritis in Slovenia. Eight consecutive rotavirus seasons were followed, from 2005/06 to 2012/13, and 113 strains of the most common rotavirus genotypes were randomly selected for molecular characterization of rotavirus VP7 and VP4 (VP8(∗)) genome segments. During the vaccine introduction period, from 2007 to 2013, rotavirus genotype prevalences changed, with G1P[8] decreasing from 74.1% to 8.7% between 2007/08 and 2010/11 seasons, replaced by G4P[8] and G2P[4], with up to 52.0% prevalence. Comparable analysis of VP7 and VP8(∗) genome fragments within G1P[8] genotype lineages revealed considerable differences for rotavirus strains circulating before and during the vaccination period. The G1P[8] rotavirus strains from the pre-vaccination period clustered in a phylogenetic tree within Rotarix®-like VP7 and VP8(∗) lineages. However, since 2007, the majority of G1P[8] strains have shifted to distant genetic lineages with lower nucleotide (88.1-94.0% for VP7 and 86.6-91.1% for VP8(∗)) and amino acid (93.8-95.2% for VP7 and 85.3-94.6% for VP8(∗)) identities to the vaccine Rotarix® strain. This change also resulted in a different deduced amino acid profile at the major VP7 and VP8(∗) antigenic epitopes.

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.

High index of suspicion of intussusception in an 8-month South African child: a case report

This case report describes diagnosis and management of intussusception in an 8-month-old baby girl seen at the Ventersdorp District Hospital, South Africa. According to the vaccination card, the child had been immunized with rotavirus vaccine with the last dose given 6 months and 2 weeks before presentation to Ventersdorp Hospital. This case of intussusception was unlikely associated with rotavirus vaccination.

African rotavirus surveillance network: a brief overview

With the imminent availability of new and prospective rotavirus vaccines, reliable information on burden of rotavirus diseases in the different African countries was required to enable evidence-based decision making regarding introduction of rotavirus vaccines. World Health Organization has been supporting Member States since 2006 to establish sentinel surveillance for rotavirus diarrhea in children <5 years of age using standardized guidelines. African countries are using this platform to generate high quality country specific data to document and demonstrate the burden of rotavirus gastroenteritis. The data gathered are being used by policy makers to guide decisions on appropriate intervention strategies for diarrhea control including the value and timing of the introduction of new rotavirus vaccines in the national immunization programs.