Efficacy of human rotavirus vaccine against rotavirus gastroenteritis during the first 2 years of life in European infants: randomised, double-blind controlled study

The rotavirus vaccine development pipeline

Rotavirus disease is a leading global cause of mortality and morbidity in children under 5 years of age. The effectiveness of the two globally used oral rotavirus vaccines quickly became apparent when introduced into both developed and developing countries, with significant reductions in rotavirus-associated mortality and hospitalizations. However, the effectiveness and impact of the vaccines is reduced in developing country settings, where the burden and mortality is highest.

New rotavirus vaccines, including live oral rotavirus candidates and non-replicating approaches continue to be developed, with the major aim to improve the global supply of rotavirus vaccines and for local implementation, and to improve vaccine effectiveness in developing settings. This review provides an overview of the new rotavirus vaccines in development by developing country manufacturers and provides a rationale why newer candidates continue to be explored. It describes the new live oral rotavirus vaccine candidates as well as the non-replicating rotavirus vaccines that are furthest along in development.

Options for improving effectiveness of rotavirus vaccines in developing countries

Rotavirus gastroenteritis is a leading global cause of mortality and morbidity in young children due to diarrhea and dehydration. Over 85% of deaths occur in developing countries. In industrialised countries, 2 live oral rotavirus vaccines licensed in 2006 quickly demonstrated high effectiveness, dramatically reducing severe rotavirus gastroenteritis admissions in many settings by more than 90%. In contrast, the same vaccines reduced severe rotavirus gastroenteritis by only 30-60% in developing countries, but have been proven life-saving. Bridging this "efficacy gap" offers the possibility to save many more lives of children under the age of 5. The reduced efficacy of rotavirus vaccines in developing settings may be related to differences in transmission dynamics, as well as host luminal, mucosal and immune factors. This review will examine strategies currently under study to target the issue of reduced efficacy and effectiveness of oral rotavirus vaccines in developing settings.

Impact of the introduction of rotavirus vaccination on paediatric hospital admissions, Lothian, Scotland: a retrospective observational study

OBJECTIVE

Rotavirus (RV) vaccination was introduced into the UK vaccination schedule in July 2013. This retrospective observational study assessed, in a UK setting, the impact of the vaccination programme on the number of RV gastroenteritis (RVGE) admissions, the complications of RVGE in hospitalised children, and the impact on hospital-acquired RVGE.

DESIGN

Over a 3 year period, 1-year before and 2 years after the introduction of the vaccine, children under 13 years of age in Lothian region with RV+ve stool sample by PCR were identified, retrospectively, and admission data (length of stay, complications) and vaccination status analysed. Viral strain (vaccine/wild type) was typed using PCR-based methods in vaccinated children.

RESULTS

Vaccination uptake in the first 2 years of the programme was 93-94%. In the 2 years following vaccine introduction, the annual number of confirmed RVGE admissions fell by 84.7% (95% CI 75.4 to 91.0), from 131 to 20, bed days reduced by 91.1% (86.9 to 94.1), from 325 to 29, and suspected hospital-acquired infections reduced by 95.7% (73.5-99.5), from 23 to 1. The reduction in admissions was seen across all age groups despite the vaccination only being administered to infants. Despite the reduction in incidence, complication rates in children admitted with RVGE remained unchanged across the three study years. A frequent incidental finding was RV vaccine strain in the stools of vaccinated children, up to 43 days after last immunisation. There has been no concurrent increase in rate of intussusception in the region.

CONCLUSIONS

These results provide encouraging initial evidence of the public health benefit, including to the unimmunised population, of the RV vaccination programme in the UK.

Efficacy of a Low-Cost, Heat-Stable Oral Rotavirus Vaccine in Niger

BACKGROUND

Each year, rotavirus gastroenteritis is responsible for about 37% of deaths from diarrhea among children younger than 5 years of age worldwide, with a disproportionate effect in sub-Saharan Africa.

METHODS

We conducted a randomized, placebo-controlled trial in Niger to evaluate the efficacy of a live, oral bovine rotavirus pentavalent vaccine (BRV-PV, Serum Institute of India) to prevent severe rotavirus gastroenteritis. Healthy infants received three doses of the vaccine or placebo at 6, 10, and 14 weeks of age. Episodes of gastroenteritis were assessed through active and passive surveillance and were graded on the basis of the score on the Vesikari scale (which ranges from 0 to 20, with higher scores indicating more severe disease). The primary end point was the efficacy of three doses of vaccine as compared with placebo against a first episode of laboratory-confirmed severe rotavirus gastroenteritis (Vesikari score, ≥11) beginning 28 days after dose 3.

RESULTS

Among the 3508 infants who were included in the per-protocol efficacy analysis, there were 31 cases of severe rotavirus gastroenteritis in the vaccine group and 87 cases in the placebo group (2.14 and 6.44 cases per 100 person-years, respectively), for a vaccine efficacy of 66.7% (95% confidence interval [CI], 49.9 to 77.9). Similar efficacy was seen in the intention-to-treat analyses, which showed a vaccine efficacy of 69.1% (95% CI, 55.0 to 78.7). There was no significant between-group difference in the risk of adverse events, which were reported in 68.7% of the infants in the vaccine group and in 67.2% of those in the placebo group, or in the risk of serious adverse events (in 8.3% in the vaccine group and in 9.1% in the placebo group); there were 27 deaths in the vaccine group and 22 in the placebo group. None of the infants had confirmed intussusception.

CONCLUSIONS

Three doses of BRV-PV, an oral rotavirus vaccine, had an efficacy of 66.7% against severe rotavirus gastroenteritis among infants in Niger. (Funded by Médecins sans Frontières Operational Center and the Kavli Foundation; ClinicalTrials.gov number, NCT02145000 .).

Human rotavirus strains circulating in Venezuela after vaccine introduction: predominance of G2P[4] and reemergence of G1P[8]

BACKGROUND

Rotavirus (RV) is the most common cause of severe childhood diarrhea worldwide. Despite Venezuela was among the first developing countries to introduce RV vaccines into their national immunization schedules, RV is still contributing to the burden of diarrhea. Concerns exist about the selective pressure that RV vaccines could exert on the predominant types and/or emergence of new strains.

RESULTS

To assess the impact of RV vaccines on the genotype distribution 1 year after the vaccination was implemented, a total of 912 fecal specimens, collected from children with acute gastroenteritis in Caracas from February 2007 to April 2008, were screened, of which 169 (18.5%) were confirmed to be RV positive by PAGE. Rotavirus-associated diarrhea occurred all year-round, although prevailed during the coolest and driest months among unvaccinated children under 24 months old. Of 165 RV strains genotyped for G (VP7) and P (VP4) by seminested multiplex RT-PCR, 77 (46.7%) were G2P[4] and 63 (38.2%) G1P[8]. G9P[8], G3P[8] and G2P[6] were found in a lower proportion (7.3%). Remarkable was also the detection of <5% of uncommon combinations (G8P[14], G8P[4], G1P[4] and G4P[4]) and 3.6% of mixed infections. A changing pattern of G/P-type distribution was observed during the season studied, with complete predominance of G2P[4] from February to June 2007 followed by its gradual decline and the reemergence of G1P[8], predominant since January 2008. Phylogenetic analysis of VP7 and VP4 genes revealed a high similarity among G2P[4] and global strains belonging to G2-II and P[4]-V lineages. The amino acid substitution 96D → N, related with reemergence of the G2 genotype elsewhere, was observed. The G1P[8] strains from Caracas were grouped into the lineages G1-I and P[8]-III, along with geographically remote G1P[8] rotaviruses, but they were rather distant from Rotarix® vaccine and pre-vaccine strains. Unique amino acid substitutions observed on neutralization domains of the VP7 sequence from Venezuelan post-vaccine G1P[8] could have conditioned their re-emergence and a more efficient dissemination into susceptible population.

CONCLUSIONS

The results suggest that natural fluctuations of genotypes in combination with forces driving the genetic evolution could determine the spread of novel strains, whose long-term effect on the efficacy of available vaccines should be determined.

A Rapid Epidemiological Tool to Measure the Burden of Norovirus Infection and Disease in Resource-Limited Settings

Background

Rapid, cost-effective tools are needed to estimate the disease burden of acute gastroenteritis (AGE) and norovirus (NoV) in resource-limited settings.

Methods

Households with children (6 weeks–17 years) in rural Guatemala were randomly enrolled into 2 parallel AGE surveillance systems: (1) a prospective cohort, which included an enrollment visit followed by 1 year of prospective observation using a smartphone-based weekly symptom diary; and (2) 2 sequential cross-sectional rapid active sampling (RAS) surveys. Norovirus testing was performed during enrollment (all subjects) and for prospective AGE episodes (prospective cohort only).

Results

The prospective cohort enrolled 207 households (469 children) from April to September 2015 followed by 471 person-years of observation; RAS survey 1 enrolled 210 households (402 children) during October to November 2015, and RAS survey 2 enrolled 210 separate households (368 children) during January to February 2016. The prospective cohort detected a NoV+ AGE prevalence of 11% and a population-attributable fraction (PAF) of −1.6% at enrollment, followed by an incidence of 1.4 episodes/100 person-years. Rapid active sampling surveys 1 and 2 identified a NoV+ AGE prevalence of 14%–21% and a PAF of 3.2%–12.4%.

Conclusions

Rapid active sampling surveys were practical and identified more cases of NoV infection and disease compared with a parallel prospective cohort in rural Guatemala.

Rotavirus immunization: Global coverage and local barriers for implementation

BACKGROUND

Rotavirus (RV) is a major agent of gastroenteritis and an important cause of child death worldwide. Immunization (RVI) has been available since 2006, and the Federation of International Societies of Gastroenterology Hepatology and Nutrition (FISPGHAN) identified RVI as a top priority for the control of diarrheal illness. A FISPGHAN working group on acute diarrhea aimed at estimating the current RVI coverage worldwide and identifying barriers to implementation at local level.

METHODS

A survey was distributed to national experts in infectious diseases and health-care authorities (March 2015-April 2016), collecting information on local recommendations, costs and perception of barriers for implementation.

RESULTS

Forty-nine of the 79 contacted countries (62% response rate) provided a complete analyzable data. RVI was recommended in 27/49 countries (55%). Although five countries have recommended RVI since 2006, a large number (16, 33%) included RVI in a National Immunization Schedule between 2012 and 2014. The costs of vaccination are covered by the government (39%), by the GAVI Alliance (10%) or public and private insurance (8%) in some countries. However, in most cases, immunization is paid by families (43%). Elevated cost of vaccine (49%) is the main barrier for implementation of RVI. High costs of vaccination (rs=-0.39, p=0.02) and coverage of expenses by families (rs=0.5, p=0.002) significantly correlate with a lower immunization rate. Limited perception of RV illness severity by the families (47%), public-health authorities (37%) or physicians (24%) and the timing of administration (16%) are further major barriers to large- scale RVI programs.

CONCLUSIONS

After 10years since its introduction, the implementation of RVI is still unacceptably low and should remain a major target for global public health. Barriers to implementation vary according to setting. Nevertheless, public health authorities should promote education for caregivers and health-care providers and interact with local health authorities in order to implement RVI.

Rotavirus specific maternal antibodies and immune response to RV3-BB neonatal rotavirus vaccine in New Zealand

BACKGROUND

Maternal antibodies, acquired passively via placenta and/or breast milk, may contribute to the reduced efficacy of oral rotavirus vaccines observed in children in developing countries. This study aimed to investigate the effect of rotavirus specific maternal antibodies on the serum IgA response or stool excretion of vaccine virus after any dose of an oral rotavirus vaccine, RV3-BB, in parallel to a Phase IIa clinical trial conducted at Dunedin Hospital, New Zealand. At the time of the study rotavirus vaccines had not been introduced in New Zealand and the burden of rotavirus disease was evident.

METHODS

Rotavirus specific IgG and serum neutralizing antibody (SNA) levels in cord blood and IgA levels in colostrum and breast milk samples collected ∼4 weeks, ∼20 weeks and ∼28 weeks after birth were measured. Infants were randomized to receive the first dose of vaccine at 0-5 d (neonatal schedule) or 8 weeks (infant schedule). Breast feeding was with-held for 30 minutes before and after vaccine administration. The relationship between rotavirus specific IgG and SNA levels in cord blood and IgA in colostrum and breast milk at the time of first active dose of RV3-BB vaccine and level of IgA response and stool excretion after 3 doses of vaccine was assessed using linear and logistic regression.

RESULTS

Forty infants received 3 doses of RV3-BB rotavirus vaccine and were included in the analysis of the neonatal and infant groups. Rotavirus specific IgA in colostrum (neonatal schedule group) and breast milk at 4 weeks (infant schedule group) was identified in 14/21 (67%) and 14/17 (82%) of infants respectively. There was little evidence of an association between IgA in colostrum or breast milk IgA at 4 weeks, or between cord IgG or SNA level, and IgA response or stool excretion after 3 doses of RV3-BB, or after one dose (neonatal schedule) (all p>0.05).

CONCLUSIONS

The level of IgA in colostrum or breast milk and level of placental IgG and SNA did not impact on the serum IgA response or stool excretion following 3 doses of RV3-BB Rotavirus Vaccine administered using either a neonatal or infant schedule in New Zealand infants.

Evaluating the first introduction of rotavirus vaccine in Thailand: Moving from evidence to policy

BACKGROUND

We assessed the effectiveness and possible impact of introducing rotavirus vaccine into the routine immunization program.

METHODS

Two provinces were selected for an observational study, one where vaccine was introduced and another where vaccine was not available. In these areas, two sub-studies were linked. The prospective cohort study enrolled children 2month old and followed them to the age of 18months to detect all diarrhea episodes. The hospital surveillance study enrolled all children up to age 5 hospitalized with diarrhea whose fecal samples were tested for rotavirus. Rates of rotavirus hospitalizations in older children who had not been vaccinated in both settings provided data to determine whether immunization had an indirect herd effect. The key endpoints for the study were both vaccine effectiveness (VE) based upon hospitalized rotavirus diarrhea and herd protection.

FINDINGS

From the cohort study, the overall VE for hospitalized rotavirus diarrhea was 88% (95%CI 76-94). Data from hospital surveillance indicated that for 2 consecutive years, the seasonal peak of rotavirus admissions was no longer present in the vaccinated area. Herd protection was observed among older children born before the rotavirus vaccine program was introduced, who experienced a 40-69% reduction in admission for rotavirus.

CONCLUSIONS

Rotavirus vaccine was highly effective in preventing diarrheal hospitalizations and in conferring herd protection among older children who had not been vaccinated.

Effectiveness of Monovalent and Pentavalent Rotavirus Vaccines in Guatemala

BACKGROUND

Concerns remain about lower effectiveness and waning immunity of rotavirus vaccines in resource-poor populations. We assessed vaccine effectiveness against rotavirus in Guatemala, where both the monovalent (RV1; 2-dose series) and pentavalent (RV5; 3-dose series) vaccines were introduced in 2010.

METHODS

A case-control evaluation was conducted in 4 hospitals from January 2012 to August 2013. Vaccine status was compared between case patients (children with laboratory-confirmed rotavirus diarrhea) and 2 sets of controls: nondiarrhea "hospital" controls (matched by birth date and site) and nonrotavirus "test-negative" diarrhea controls (adjusted for age, birth month/year, and site). Vaccine effectiveness ([1 - odds ratio of vaccination] × 100%) was computed using logistic regression models.

RESULTS

We evaluated 213 case patients, 657 hospital controls, and 334 test-negative controls. Effectiveness of 2-3 doses of a rotavirus vaccine against rotavirus requiring emergency department visit or hospitalization was 74% (95% confidence interval [CI], 58%-84%) with hospital controls, and 52% (95% CI, 26%-69%) with test-negative controls. Using hospital controls, no significant difference in effectiveness was observed between infants 6-11 months (74% [95% CI, 18%-92%]) and children ≥12 months of age (71% [95% CI, 44%-85%]) (P= .85), nor between complete courses of RV1 (63% [95% CI, 23%-82%]) and RV5 (69% [95% CI, 29%-87%]) (P= .96). An uncommon G12P[8] strain, partially heterotypic to strains in both vaccines, was identified in 89% of cases.

CONCLUSIONS

RV1 and RV5 were similarly effective against severe rotavirus diarrhea caused by a heterotypic strain in Guatemala. This supports broader implementation of rotavirus vaccination in low-income countries where >90% global deaths from rotavirus occur.

Changing molecular epidemiology of rotavirus infection after introduction of monovalent rotavirus vaccination in Scotland

BACKGROUND

Rotaviruses (RV) are the leading cause of gastroenteritis in children less than five years of age worldwide. Rotarix®, a live attenuated monovalent vaccine containing a RV strain of G1P[8] specificity has been included in the childhood immunisation schedule from June 2013 in Scotland. This study aimed to characterise the prevalent RV strains in Scotland before and after the introduction of the RV vaccine.

METHODS

RV positive faecal samples from Scottish virology laboratories covering the years 2012-2015 were genotyped. Viral RNA was extracted from faecal suspensions. VP7 and VP4 gene specific primers were used for multiplex hemi-nested PCRs and sequencing. Mann-Whitney U test and Chi-square test were used for statistical comparison.

RESULTS

There was a decrease in RV positive samples from the Scottish virology laboratories from 7409 samples in the pre-vaccination years (2009-2013) to 760 in 2014-2015, with an annual reduction of RV infections by 74.4% (RR-3.95; 95%-CI, 3.53-4.42, p<0.001). 362 samples from the pre-vaccination period and 278 samples from the post-vaccination were genotyped. There was a drop in prevalence of G1P[8] strains (72.1%, 95%-CI, 67.42-76.33 to 15%, 95%-CI, 11.38-19.79) after introduction of the vaccine. In the post-vaccination period G2P[4] was the dominant strain in Scotland (21.9%, 95%-CI, 17.48-27.17) with increase in G9P[8] (12.9%, 95%-CI, 9.50-7.41), G12P[8] (12.2%, 95%-CI, 8.89-16.60) and G3P[8] (11.9%, 95%-CI, 8.58-16.20) infections. Phylogenetic analysis of the VP7 and VP4 genes showed no major differences between the pre and post-vaccination G1P[8] strains.

CONCLUSION

This laboratory based surveillance study shows significant reduction in reported RV cases and a shift in proportion from G1P[8] to G2P[4] strains after introduction of RV vaccination in Scotland. The genotyping data from a subset of the total reported RV cases will be used to ascertain cross protection against strains and identify vaccine induced RV strain shifts in the years to come.

Emergence of human G2P[4] rotaviruses containing animal derived gene segments in the post-vaccine era

The introduction of Rotarix into the Belgian immunization program in June 2006 coincided with an increase of the relative prevalence of G2P[4] strains. However, the genetic composition of these persistent G2P[4] strains has not been investigated. Therefore, we have investigated the NSP4 gene of 89 Belgian G2P[4] strains detected between 1999 and 2013, covering both pre- and post-vaccination periods. The NSP4 genes were divided over seven separate clusters of which six were more closely related to animal than to human strains. The NSP4 genes that clustered more closely to animal DS-1-like strains were isolated after 2004–2005 and were found throughout multiple seasons. Complete genome sequencing of 28 strains identified several other gene segments that clustered more closely to animal than to human DS-1-like strains. These findings suggest that frequent interspecies reassortments may have played a role in the spread of G2P[4] rotaviruses in the post-vaccination period in Belgium.

Rotavirus vaccine and health-care utilization for rotavirus gastroenteritis in Tsu City, Japan

Background

Rotavirus vaccines were introduced in Japan in November 2011. We evaluated the subsequent reduction of the health-care burden of rotavirus gastroenteritis.

Methods

We conducted active surveillance for rotavirus gastroenteritis among children under 5 years old before and after the vaccine introduction. We surveyed hospitalization rates for rotavirus gastroenteritis in children in Tsu City, Mie Prefecture, Japan, from 2007 to 2015 and surveyed the number of outpatient visits at a Tsu City clinic from 2010 to 2015. Stool samples were obtained for rotavirus testing and genotype investigation. We assessed rotavirus vaccine coverage for infants living in Tsu City.

Results

In the pre-vaccine years (2007–2011), hospitalization rates for rotavirus gastroenteritis in children under 5 years old were 5.5, 4.3, 3.1 and 3.9 cases per 1000 person-years, respectively. In the post-vaccine years (2011–2015), the rates were 3.0, 3.5, 0.8 and 0.6 cases per 1000 person-years, respectively. The hospitalization rate decreased significantly in the 2013–2014 and 2014–2015 seasons compared to the average of the seasons before vaccine introduction (P < 0.0001). In one pre-vaccine year (2010–2011), the number of outpatient visits due to the rotavirus infection was 66. In the post-vaccine years (2011–2015), the numbers for each season was 23, 23, 7 and 5, respectively. The most dominant rotavirus genotype shifted from G3P[8] to G1P[8] and to G2P[4]. The coverage of one dose of rotavirus vaccine in Tsu City was 56.5% in 2014.

Conclusion

After the vaccine introduction, the hospitalization rates and outpatient visits for rotavirus gastroenteritis greatly decreased.

Rotavirus vaccines contribute towards universal health coverage in a mixed public-private healthcare system

OBJECTIVES

To evaluate rotavirus vaccination in Malaysia from the household's perspective. The extended cost-effectiveness analysis (ECEA) framework quantifies the broader value of universal vaccination starting with non-health benefits such as financial risk protection and equity. These dimensions better enable decision-makers to evaluate policy on the public finance of health programmes.

METHODS

The incidence, health service utilisation and household expenditure related to rotavirus gastroenteritis according to national income quintiles were obtained from local data sources. Multiple birth cohorts were distributed into income quintiles and followed from birth over the first five years of life in a multicohort, static model.

RESULTS

We found that the rich pay more out of pocket (OOP) than the poor, as the rich use more expensive private care. OOP payments among the poorest although small are high as a proportion of household income. Rotavirus vaccination results in substantial reduction in rotavirus episodes and expenditure and provides financial risk protection to all income groups. Poverty reduction benefits are concentrated amongst the poorest two income quintiles.

CONCLUSION

We propose that universal vaccination complements health financing reforms in strengthening Universal Health Coverage (UHC). ECEA provides an important tool to understand the implications of vaccination for UHC, beyond traditional considerations of economic efficiency.

Significant Correlation Between the Infant Gut Microbiome and Rotavirus Vaccine Response in Rural Ghana

Background

Rotavirus (RV) is the leading cause of diarrhea-related death in children worldwide and 95% of RV-associated deaths occur in Africa and Asia where RV vaccines (RVVs) have lower efficacy. We hypothesize that differences in intestinal microbiome composition correlate with the decreased RVV efficacy observed in poor settings.

Methods

We conducted a nested, case-control study comparing prevaccination, fecal microbiome compositions between 6-week old, matched RVV responders and nonresponders in rural Ghana. These infants' microbiomes were then compared with 154 age-matched, healthy Dutch infants' microbiomes, assumed to be RVV responders. Fecal microbiome analysis was performed in all groups using the Human Intestinal Tract Chip.

Results

We analyzed findings in 78 Ghanaian infants, including 39 RVV responder and nonresponder pairs. The overall microbiome composition was significantly different between RVV responders and nonresponders (FDR, 0.12), and Ghanaian responders were more similar to Dutch infants than nonresponders (P = .002). RVV response correlated with an increased abundance of Streptococcus bovis and a decreased abundance of the Bacteroidetes phylum in comparisons between both Ghanaian RVV responders and nonresponders (FDR, 0.008 vs 0.003) and Dutch infants and Ghanaian nonresponders (FDR, 0.002 vs 0.009).

Conclusions

The intestinal microbiome composition correlates significantly with RVV immunogenicity and may contribute to the diminished RVV immunogenicity observed in developing countries.

Economic evaluation of routine infant rotavirus immunisation program in Japan

Two rotavirus vaccines are currently available in Japan. We estimated the incremental cost-effectiveness ratio (ICER) of routine infant rotavirus immunisation program without defining which vaccine to be evaluated, which reflects the current deliberation at the Health Science Council in charge of Immunisation and Vaccine established by the Ministry of Health, Labor and Welfare of Japan. Three ICERs were estimated, one from payers' perspective and 2 from societal perspective depending on the scenarios to uptake vaccines. The health statuses following the birth cohort were as follows: not infected by rotavirus, asymptomatic infection, outpatients after infection, hospitalised after infection, developing encephalitis/encephalopathy followed by recovery, sequelae, and death. Costs of per course of vaccination was ¥30,000 (US$283; US$1 = ¥106). The model runs for 60 months with one month cycle. From payers' perspective, estimated ICERs were ¥6,877,000 (US$64,877) per QALY. From societal perspective, immunisation program turns out to be cost-saving for 75% simultaneous vaccination scenario, while it is at ¥337,000 (US$3,179) per QALY gained with vaccine alone scenario. The probability of rotavirus immunisation program to be under ¥5,000,000 (US$47,170) per QALY was at 19.8%, 40.7%, and 75.6% when costs per course of vaccination were set at ¥30,000 (US$283), ¥25,000 (US$236), and ¥20,000 (US$189), respectively. Rotavirus immunisation program has a potential to be cost-effective from payers' perspective and even cost-saving from societal perspective in Japan, however, caution should be taken with regard to the interpretation of the results as cost-effectiveness is critically dependent on vaccination costs.

Multicenter prospective study on the burden of rotavirus gastroenteritis in children less than 3 years of age in Spain

Background

Rotavirus is acknowledged as an important cause of paediatric gastroenteritis worldwide. In Spain, comprehensive data on the burden of rotavirus disease was lacking.

Methods

A prospective, multicenter, observational study was carried out, during the winter season, from October to April 2014 in selected areas of Spain (Catalonia, Basque Country, Andalusia) to estimate the frequency and characteristics of acute gastroenteritis (AGE) and rotavirus gastroenteritis (RVGE) in children ≤3 years of age seeking medical care in primary care and emergency department centres.

Results

Of the 1087 episodes of AGE registered, 33.89 % were RVGE positive. The estimated incidence of RVGE, was 40.3 (95 % CI 36.1–44.8) episodes per 10,000 child-months in children ≤ 3 years of age and the 5-month (December-April) seasonal RVGE incidence rate was 2.01 [1.81–2.24] per 100 children. No vaccination and attending a day care centre were the main risk factors for RV infection. RVGE infected children presented more frequently with fever (63.9 % vs. 45.1 %, p = 0.009), vomiting (61.2 % vs. 44.3 %, p = 0.015), suffered more dehydration, and were hospitalised and went to the emergency room more often (41.7 % vs. 15.7 %, p <0.001) than non-RVGE infected ones. Children were usually more tired (77.5 % vs. 54.2 %, p <0.001), tearful, (47.2 % vs. 34.8 %, p <0.001), and easily irritated (76.5 % vs. 59.8 %, p <0.001), and parents were more concerned (41.7 % vs. 15.7 %, p <0.001) and suffered more working rhythm disturbances (39.0 % vs. 22.9 %, p <0.001). The cost for families of RVGE cases was significantly higher than the cost of non-RVGE infected ones (47.3 vs 36.7 euros, p = 0.011). Vaccinated children suffered less clinical symptoms and no hospitalization. Therefore, vaccination decreases the psychosocial stressors caused by the disease in the family.

Conclusions

Rotavirus infections are responsible for a substantial proportion of AGE cases in children ≤3 years of age in Spain attended at primary care visits. RVGE episodes are associated with greater clinical severity, greater alterations in the child´s behaviour, and higher parental distress. The outcomes of the present study recommend that routine rotavirus vaccination in infants ≤3 years of age could considerably reduce the serious burden of this potentially serious childhood disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1890-7) contains supplementary material, which is available to authorized users.

The Sustained Rotavirus Vaccination Impact on Nosocomial Infection, Duration of Hospital Stay, and Age: The RotaBIS Study (2005-2012)

Introduction

The benefits of rotavirus (RV) vaccination in developed countries have focused on reductions in mortality, hospitalization and medical visits, and herd protection. We investigated other aspects related to RV-induced nosocomial infection, duration of hospital stay, age shift, and sustained vaccine impact (VI) over time.

Method

RotaBIS (Rotavirus Belgian Impact Study; ClinicalTrials.gov identifier, NCT01563146) annually collects retrospective data on hospitalization linked to RV testing in children up to 5 years old from 11 pediatric wards located all over Belgium. Data from 2005 to 2012 have been split in pre- (2005–2006) and post-vaccination (2007–2012) period. Information was collected on age, gender, RV test result, nosocomial infection caused by RV and duration of hospital stay.

Results

Over the 6-year period after the introduction of the RV vaccine, an 85% reduction in nosocomial infections was observed (221 in 2005 to 33 in 2012, p < 0.001). A significant reduction of almost 2 days in average duration of hospital stay per event was observed overall (7.62 days in 2005 to 5.77 days in 2012, p < 0.001). The difference is mainly explained by the higher reduction in number of nosocomial infections. A pronounced age shift (+24%, p < 0.01) of RV nosocomial infection to infants ≤2 months old was observed, increasing with length of post-vaccination period. VI was maintained over the follow-up (±79% VI per birth cohort). A decrease was seen depending on age, 85% (95% CI 76–91%) in the youngest to 63% (95% CI 22–92%) in the oldest age group.

Conclusion

The higher reduction in nosocomial infection may affect the overall average duration of hospital stay for RV infection. No change in VI by birth cohort, but a reduction by age group was observed. These findings could be important for decision-makers considering the introduction of universal mass RV vaccination programs.

Trial registration

ClinicalTrials.gov identifier, NCT01563146.

Funding

GlaxoSmithKline Biologicals SA (Rixensart, Belgium).

Post-marketing safety surveillance conducted in Korea (2008-2013) following the introduction of the rotavirus vaccine, RIX4414 (Rotarix™)

PURPOSE

According to regulations from the Ministry of Food and Drug Safety in Korea, additional safety information on the use of Rotarix™ vaccine (RIX4414; GSK, Belgium) in ≥3000 evaluable Korean infants was required following vaccine registration. In order to comply with these regulations, we conducted a 6-year open, non-comparative, multicenter post-marketing surveillance (NCT00750893).

METHODS

During this time, the original lyophilized vaccine formulation of RIX4414 was replaced by a liquid formulation. Healthy infants aged ≥6 weeks were enrolled and given 2 doses of the RIX4414 vaccine, separated by an interval of ≥4 weeks. The overall incidence of adverse events (AEs) (expected and unexpected) was then assessed for up to 30 days along with the incidence of serious adverse events (SAEs). Adverse drug reactions (ADRs: any AE whose causality to the drug could not be ruled out) were identified.

RESULTS

A total of 3040 children (mean age: 9.55 weeks) were analyzed. One or more expected AE was experienced by 30.5% infants and 8.6% had an ADR. The most commonly seen expected AE was irritability (14.0%). One or more unexpected AE was seen in 32.5% infants and 3.1% experienced an ADR. The most commonly seen unexpected AE was upper respiratory tract infection (8.7%). Of 34 SAEs recorded in 24 subjects, none were related to vaccination.

CONCLUSIONS

We conclude that this 6-year surveillance showed both formulations of RIX4414 to have acceptable safety profiles when administered to Korean infants according to local prescribing recommendations and current clinical practice.

Effectiveness of rotavirus vaccine in preventing severe gastroenteritis in young children according to socioeconomic status

In 2011, the monovalent rotavirus vaccine was introduced into a universal immunization program in Quebec (Canada). This retrospective cohort study assessed vaccine effectiveness (VE) in preventing acute gastroenteritis (AGE) and rotavirus gastroenteritis (RVGE) hospitalizations among children <3 y living in the Quebec Eastern Townships region according to socioeconomic status (SES). Data were gathered from a tertiary hospital database paired with a regional immunization registry. Three cohorts of children were followed: (1) vaccinated children born in post-universal vaccination period (2011-2013, n = 5,033), (2) unvaccinated children born in post-universal vaccination period (n = 1,239), and (3) unvaccinated children born in pre-universal vaccination period (2008-2010, n = 6,436). In each cohort, AGE and RVGE hospitalizations were identified during equivalent follow-up periods to calculate VE globally and according to neighborhood-level SES. Using multivariable logistic regression, adjusted odds ratios (OR) were computed to obtain VE (1-OR). Adjusted VE of 2 doses was 62% (95% confidence interval [CI]: 37%-77%) and 94% (95%CI: 52%-99%) in preventing AGE and RVGE hospitalization, respectively. Stratified analyses according to SES showed that children living in neighborhoods with higher rates of low-income families had significantly lower VE against AGE hospitalizations compared to neighborhoods with lower rates of low-income families (30% vs. 78%, p = 0.027). Our results suggest that the rotavirus vaccine is highly effective in preventing severe gastroenteritis in young children, particularly among the most well-off. SES seems to influence rotavirus VE, even in a high-income country like Canada. Further studies are needed to determine factors related to lower rotavirus VE among socioeconomically disadvantaged groups.

A Systematic Review of the Effect of Rotavirus Vaccination on Diarrhea Outcomes Among Children Younger Than 5 Years

BACKGROUND

Rotavirus is the leading cause of vaccine-preventable diarrhea among children under 5 globally. Rotavirus vaccination has been shown to prevent severe rotavirus infections with varying efficacy and effectiveness by region.

METHODS

We sought to generate updated region-specific estimates of rotavirus vaccine efficacy and effectiveness. We systematically reviewed published vaccine efficacy and effectiveness studies to assess the region-specific effect of rotavirus vaccination on select diarrheal morbidity and mortality outcomes in children under 5 years of age. We employed meta-analytic methods to generate pooled effect sizes by Millennium Development Goal region.

RESULTS

Rotavirus vaccination was both efficacious and effective in preventing rotavirus diarrhea, severe rotavirus diarrhea and rotavirus hospitalizations among children under 5 across all regions represented by the 48 included studies. Efficacy against severe rotavirus diarrhea ranged from 90.6% [95% confidence interval (CI): 82.3-95.0] in the developed region to 88.4% (95% CI: 67.1-95.9) in Eastern/Southeastern Asia, 79.6% (95% CI: 71.3-85.5) in Latin America and the Caribbean, 50.0% (95% CI: 34.4-61.9) in Southern Asia and 46.1% (95% CI: 29.1-59.1) in sub-Saharan Africa. Region-specific effectiveness followed a similar pattern. There was also evidence of vaccine efficacy against severe diarrhea and diarrheal hospitalizations.

CONCLUSION

Our findings confirm the protective efficacy and effectiveness of rotavirus vaccination against rotavirus diarrheal outcomes among children under 5 globally.

Issues in pediatric vaccine-preventable diseases in low- to middle-income countries

The highest burden of pediatric vaccine-preventable disease is found in developing nations where resource constraints pose the greatest challenge, impacting disease diagnosis and surveillance as well as the implementation of large scale vaccination programmes. In November 2012, a Working Group Meeting convened in Casablanca to describe and discuss the status with respect to 8 vaccine-preventable diseases (pertussis, pneumococcal disease, measles-mumps-rubella-varicella (MMRV), rotavirus and meningococcal meningitis) to identify and consider ways of overcoming obstacles to pediatric vaccine implementation. Experts from Europe, Russia, the Commonwealth of Independent States, the Middle East, Africa and South East Asia participated in the meeting. A range of region-specific needs and barriers to uptake were discussed. The aim of this article is to provide a summary of the ongoing status with respect to pediatric vaccine preventable disease in the countries represented, and the experts' opinions and recommendations with respect to pediatric vaccine implementation.

The impact of rotavirus vaccination on emergency department visits and hospital admissions for acute diarrhea in children under 5 years

Summary Introduction: Acute diarrheal disease is the second cause of death in children under 5 years. In Brazil, from 2003 to 2009, acute diarrhea was responsible for nearly 100,000 hospital admissions per year and 4% of the deaths in children under 5 years. Rotavirus is the leading cause of severe acute diarrhea worldwide. In 2006, the rotavirus monovalent vaccine (RV1) was added to the Brazilian National Immunization Program. Objectives: To analyze the impact of the RV1 on emergency department (ED) visits and hospital admissions for acute diarrhea. Method: A retrospective ecologic study at the University Hospital, University of São Paulo. The study analyzed the pre-vaccine (2003–2005) and the post-vaccine (2007–2009) periods. We screened the main diagnosis of all ED attendances and hospital admissions of children under 5 years in an electronic registry system database and calculated the rates of ED visits and hospital admissions. The reduction rate was analyzed according to the following formula: reduction (%) = (1 - odds ratio) x 100. Results: The rates of ED visits for acute diarrhea was 85.8 and 80.9 per 1,000 total ED visits in the pre and post vaccination periods, respectively, resulting in 6% reduction (95CI 4 to 9%, p<0.001). The rates of hospital admissions for acute diarrhea was 40.8 per 1,000 in the pre-vaccine period and dropped to 24.9 per 1,000 hospitalizations, resulting in 40% reduction (95CI 22 to 54%, p<0.001). Conclusion: The introduction of the RV1 vaccine resulted in 6% reduction in the ED visits and 40% reduction in hospital admissions for acute diarrhea.

Findings from a comprehensive diarrhoea prevention and treatment programme in Lusaka, Zambia

BACKGROUND

The Programme for the Awareness and Elimination of Diarrhoea (PAED) was a pilot comprehensive diarrhoea prevention and control programme aimed to reduce post-neonatal, all-cause under-five mortality by 15 % in Lusaka Province. Interventions included introduction of the rotavirus vaccine, improved clinical case management of diarrhoea, and a comprehensive community prevention and advocacy campaign on hand washing with soap, exclusive breastfeeding up to 6 months of age, and the use of ORS and Zinc. This study aimed to assess the impact of PAED on under-5 mortality.

METHODS

The study was a pre-post evaluation design. The Demographic and Health Survey style population-based two-stage approach was used to collect data at the beginning of the intervention and 3 years following the start of intervention implementation in Lusaka province. The primary outcome of interest was an all-cause, post-neonatal under-five mortality rate defined as the probability of dying after the 28th day and before the fifth birthday among children aged 1-59 months. The Kaplan-Meier time to event analysis was used to estimate the probability of death; multiplying this probability by 1000 to yield the post-neonatal mortality rate. Survival-time inverse probability weighting model was used to estimate Average Treatment Effect (ATE).

RESULTS

The percentage of children under age 5 who had diarrhoea in the last 2 weeks preceding the survey declined from 15.8 % (95 % CI: 15.2 %, 16.4 %) in 2012 to 12.7 % (95 % CI: 12.3 %, 13.2 %) in 2015. Over the same period, mortality in post-neonatal children under 5 years of age declined by 34 %, from an estimated rate of 29 deaths per 1000 live births (95 % CI: (26, 32) death per 1000 live births) to 19 deaths per 1000 live births (95 % CI: (16, 21) death per 1000 live births). When every child in the population of children aged 1-59 months is exposed to the intervention, the average time-to-death was estimated to be about 8 months more than when no child is exposed (ATE = 7.9; 95 % CI: 4.4,11.5; P < 0.001).

CONCLUSION

Well-packaged diarrhoea preventive and treatment interventions delivered at the clinic and community-level could potentially reduce probability of death among children aged 1-59 months.

Incidence of rotavirus gastroenteritis by age in African, Asian and European children: Relevance for timing of rotavirus vaccination

Variability in rotavirus gastroenteritis (RVGE) epidemiology can influence the optimal vaccination schedule. We evaluated regional trends in the age of RVGE episodes in low- to middle- versus high-income countries in three continents. We undertook a post-hoc analysis based on efficacy trials of a human rotavirus vaccine (HRV; Rotarix™, GSK Vaccines), in which 1348, 1641, and 5250 healthy infants received a placebo in Europe (NCT00140686), Africa (NCT00241644), and Asia (NCT00197210, NCT00329745). Incidence of any/severe RVGE by age at onset was evaluated by active surveillance over the first two years of life. Severity of RVGE episodes was assessed using the Vesikari-scale. The incidence of any RVGE in Africa was higher than in Europe during the first year of life (≤2.78% vs. ≤2.03% per month), but much lower during the second one (≤0.86% versus ≤2.00% per month). The incidence of severe RVGE in Africa was slightly lower than in Europe during the first year of life. Nevertheless, temporal profiles for the incidence of severe RVGE in Africa and Europe during the first (≤1.00% and ≤1.23% per month) and second (≤0.53% and ≤1.13% per month) years of life were similar to those of any RVGE. Any/severe RVGE incidences peaked at younger ages in Africa vs. Europe. In high-income Asian regions, severe RVGE incidence (≤0.31% per month) remained low during the study. The burden of any RVGE was higher earlier in life in children from low- to middle- compared with high-income countries. Differing rotavirus vaccine schedules are likely warranted to maximize protection in different settings.

The effectiveness of rotavirus vaccine in preventing acute gastroenteritis during rotavirus seasons among Polish children

INTRODUCTION

Rotavirus is the main etiological cause of intestinal infections in children. Voluntary rotavirus vaccines were included in the Polish vaccination schedule in 2007. The aim of this study was to assess the effectiveness of a completed rotavirus vaccination course in preventing acute gastroenteritis in Polish infants during their first five years of life.

MATERIAL AND METHODS

This was a retrospective cohort study conducted in Lesser Poland (Malopolska Province). The sample population included a group of 303 children who received the completed rotavirus vaccination course and 303 children not vaccinated against rotavirus. The date of the child's acute gastroenteritis diagnosis and his or her vaccination history were extracted from the physicians' records. Each kind of diagnosed acute gastroenteritis during winter-spring rotavirus seasons was treated as the endpoint. The relative risk of having gastrointestinal infection was assessed using the hazard ratio from the Cox proportional hazards regression model.

RESULTS

In the examined group, 96 (15.8%) children had winter-spring gastrointestinal infections. In the non-vaccinated children, the cumulative incidence of these infections in the first 5 years of life was 20.8%, whereas in the children vaccinated with Rotarix it was only 10.9%. Those who were vaccinated with Rotarix had a 44% reduction in the risk of a winter-spring acute gastroenteritis infection compared to those not vaccinated with Rotarix (p = 0.005). Birth weight less than 2500 g increased the risk of the infection twofold and also reached statistical significance (p = 0.044).

CONCLUSIONS

The results showed that Rotarix is effective in preventing acute gastroenteritis in Polish children during rotavirus seasons.

Identification of a Peptide Produced by Bifidobacterium longum CECT 7210 with Antirotaviral Activity

Rotavirus is one of the main causes of acute diarrhea and enteritis in infants. Currently, studies are underway to assess the use of probiotics to improve rotavirus vaccine protection. A previous work demonstrated that the probiotic strain Bifidobacterium longum subsp. infantis CECT 7210 is able to hinder rotavirus replication both in vitro and in vivo. The present study takes a systematic approach in order to identify the molecule directly involved in rotavirus inhibition. Supernatant protease digestions revealed both the proteinaceous nature of the active substance and the fact that the molecule responsible for inhibiting rotavirus replication is released to the supernatant. Following purification by cationic exchange chromatography, active fractions were obtained and the functional compound was identified as an 11-amino acid peptide (MHQPHQPLPPT, named 11-mer peptide) with a molecular mass of 1.282 KDa. The functionality of 11-mer was verified using the synthesized peptide in Wa, Ito, and VA70 rotavirus infections of both HT-29 and MA-104 cell lines. Finally, protease activity was detected in B. longum subsp. infantis CECT 7210 supernatant, which releases 11-mer peptide. A preliminary identification of the protease is also included in the study.

Sustained Reduction of Childhood Diarrhea-Related Mortality and Hospitalizations in Mexico After Rotavirus Vaccine Universalization

BACKGROUND

Mexico implemented routine childhood vaccination against rotavirus in 2007. We describe trends in hospitalization and deaths from diarrhea among children aged <5 years in Mexico before and 7 years after implementation of rotavirus vaccination.

METHODS

We obtained data on deaths and hospitalizations from diarrhea, from January 2003 through December 2014, in Mexican children <5 years of age. We compared diarrhea-related mortality and hospitalizations in the postvaccine era with the prevaccine baseline from 2003 to 2006.

RESULTS

Compared with the prevaccine baseline, we observed a 53% reduction (95% confidence interval [CI], 47%-58%) in diarrhea-related mortality and a 47% reduction (95% CI, 45%-48%) in diarrhea-related hospitalizations in postvaccine years, translating to 959 deaths and 5831 hospitalizations averted every year in Mexican children aged <5 years. Prevaccine peaks in diarrhea-related mortality and hospitalizations during the rotavirus season months were considerably diminished in postvaccine years, with greater declines observed during the rotavirus season compared with non-rotavirus season months.

CONCLUSIONS

We document a substantial and sustained decline in diarrhea-related hospitalizations and deaths in Mexican children associated with implementation of rotavirus vaccination. These results highlight the public health benefits that could result in countries that adopt rotavirus vaccination into their national immunization programs.

Temporal Association of Rotavirus Vaccine Introduction and Reduction in All-Cause Childhood Diarrheal Hospitalizations in South Africa

BACKGROUND

The public health impact of rotavirus vaccination in African settings with a high human immunodeficiency virus (HIV) infection prevalence is yet to be established. We evaluated trends in all-cause diarrheal hospitalizations in Soweto, Johannesburg, before and after the introduction of rotavirus vaccine into South Africa's national immunization program in August 2009.

METHODS

Hospitalizations in children <5 years of age with a diagnosis of diarrhea, defined byInternational Classification of Diseases, Tenth Revisioncodes A00-A05, A06.0-A06.3, A06.9, A07.0-A07.2, A07.9, and A08-A09, were identified at the Chris Hani Baragwanath Academic Hospital from 1 January 2006 to 31 December 2014. The median annual prevaccine (2006-2008) hospitalization incidence was compared to that of the vaccine era (2010-2014), and stratified by age group and HIV infection status.

RESULTS

Incidence reductions (per 1000 population) were greatest in children aged <12 months: 54.4 in the prevaccine era vs 30.0, 23.6, 20.0, 18.8, and 18.9 in the postvaccine years 2010-2014, respectively (a 44.9%-65.4% reduction). Lower incidence reductions (39.8%-49.4%) were observed among children aged 12-24 months from the second year post-vaccine introduction onward. Reductions were observed in both HIV-infected and HIV-uninfected children. There was a change in the seasonal pattern of diarrheal hospitalizations post-vaccine introduction, with flattening of the autumn-winter peaks seen in the prevaccine years.

CONCLUSIONS

An accelerated and sustained decline in all-cause diarrheal hospitalizations, temporally associated with rotavirus vaccine introduction, was observed in children <2 years of age. However, the impact of other interventions such as improved sanitation and changes in HIV management cannot be discounted.

A Preliminary Assessment of Rotavirus Vaccine Effectiveness in Zambia

BACKGROUND

Diarrhea is the third leading cause of child death in Zambia. Up to one-third of diarrhea cases resulting in hospitalization and/or death are caused by vaccine-preventable rotavirus. In January 2012, Zambia initiated a pilot introduction of the Rotarix live, oral rotavirus vaccine in all public health facilities in Lusaka Province.

METHODS

Between July 2012 and October 2013, we conducted a case-control study at 6 public sector sites to estimate rotavirus vaccine effectiveness (VE) in age-eligible children presenting with diarrhea. We computed the odds of having received at least 1 dose of Rotarix among children whose stool was positive for rotavirus antigen (cases) and children whose stool was negative (controls). We adjusted the resulting odds ratio (OR) for patient age, calendar month of presentation, and clinical site, and expressed VE as (1 - adjusted OR) × 100.

RESULTS

A total of 91 rotavirus-positive cases and 298 rotavirus-negative controls who had under-5 card-confirmed vaccination status and were ≥6 months of age were included in the case-control analysis. Among rotavirus-positive children who were age-eligible to be vaccinated, 20% were hospitalized. Against rotavirus diarrhea of all severity, the adjusted 2-dose VE was 26% (95% confidence interval [CI], -30% to 58%) among children ≥6 months of age. VE against hospitalized children ≥6 months of age was 56% (95% CI, -34% to 86%).

CONCLUSIONS

We observed a higher point estimate for VE against increased severity of illness compared with milder disease, but were not powered to detect a low level of VE against milder disease.

Effectiveness of Pentavalent Rotavirus Vaccine Against a Diverse Range of Circulating Strains in Nicaragua

BACKGROUND

Because >60 rotavirus strains have been reported worldwide, concerns exist about strain replacement after the introduction of rotavirus vaccines, particularly in developing countries with diverse strains and lower efficacy.

METHODS

We used the case-control design in 4 hospitals in Nicaragua to assess strain-specific vaccine effectiveness (VE) of a pentavalent rotavirus vaccine (RotaTeq) against rotavirus diarrhea. Cases were identified through prospective strain surveillance with reverse transcription-polymerase chain reaction for 3 years among children hospitalized for diarrhea, and controls were children negative for rotavirus.

RESULTS

We enrolled 1178 case-patients, 1082 (92%) with G and P typing, and 4927 controls. A different strain predominated each year with increasing age of the vaccine-eligible cohort during the study period: G2P[4] in 2008 (97%; mean age, 11.9 months), G1P[8] in 2009 (55%; mean age, 17.0 months), and G3P[8] in 2010 (78%; mean age, 17.3 months). Overall VE was 45% (95% confidence interval, 25%-59%). Regardless of the strain, VE estimates were 12%-79% lower among children aged ≥12 months relative to those 6-11 months of age. The lower VE for G3P[8] was related to the higher mean age of cases (17.3 months) compared with the G2P[4] strains (11.9 months), with a significant trend (R(2)= 0.819;P< .001) of declining effectiveness with increasing mean age of the cases.

CONCLUSIONS

Introduction of RotaTeq did not result in sustained emergence of any particular strain in Nicaragua. Variation in strain-specific effectiveness was due to an age-related decline in effectiveness rather than differences in protection against the observed strains.

Rotavirus Surveillance at a WHO-Coordinated Invasive Bacterial Disease Surveillance Site in Bangladesh: A Feasibility Study to Integrate Two Surveillance Systems

The World Health Organization (WHO) currently coordinates rotavirus diarrhea and invasive bacterial disease (IBD) surveillance at 178 sentinel sites in 60 countries. However, only 78 sites participate in both surveillance systems using a common sentinel site. Here, we explored the feasibility of extending a WHO-IBD surveillance platform to generate data on the burden of rotaviral diarrhea and its epidemiological characteristics to prepare the countries to measure the impact of rotaviral vaccine. A six-month (July to December, 2012) surveillance, managed by IBD team, collected stool samples and clinical data from under-five children with acute watery diarrhea at an IBD sentinel site. Samples were tested for rotavirus antigen by ELISA and genotyped by PCR at the regional reference laboratory (RRL). Specimens were collected from 79% (n = 297) of eligible cases (n = 375); 100% of which were tested for rotavirus by ELISA and 54% (159/297) of them were positive. At RRL, all the cases were confirmed by PCR and genotyped (99%; 158/159). The typing results revealed the predominance of G12 (40%; 64/159) genotype, followed by G1 (31%; 50/159) and G9 (19%; 31/159). All in all, this exploratory surveillance collected the desired demographic and epidemiological data and achieved almost all the benchmark indicators of WHO, starting from enrollment number to quality assurance through a number of case detection, collection, and testing of specimens and genotyping of strains at RRL. The success of this WHO-IBD site in achieving these benchmark indicators of WHO can be used by WHO as a proof-of-concept for considering integration of rotavirus surveillance with WHO-IBD platforms, specifically in countries with well performing IBD site and no ongoing rotavirus surveillance.

Introduction of a new Rotavirus vaccine: Initial results of uptake and impact on laboratory confirmed cases in Anglia and Essex, United Kingdom, July 2015

Rotavirus gastroenteritis accounts for an estimated 130,000 GP consultations and 13,000 hospitalisations for children under 5 y old each year in England and Wales. In July 2013, an oral live attenuated rotavirus vaccine (Rotarix®) was introduced into the UK infant immunisation program as a 2 dose schedule at 2 and 3 months of age. We collected vaccination uptake from October 2013 to March 2015 and laboratory confirmed cases data on children under the age of 5 y from 1 January 2004 to 31 May 2015. The vaccine uptake rates and laboratory confirmed cases were compared to provide evidence of the impact of this vaccination program. Vaccine uptake rates were available from sentinel data with between 91-98% of GP practices in Anglia and Essex providing data every month. These data showed from February 2014 to March 2015 between 90-92% of infants received the recommended 2 doses of Rotarix® each month. The numbers of rotavirus cases reported by laboratories decreased on average by 82% in the post vaccination seasons. The mean number of cases reported in weeks 1-22 for 2004-2013 in Anglia and Essex was 1,318. For the same period in 2014, 256 cases were reported and initial data for 2015 report 226 cases. In the first 5 months 2014 the greatest reduction in cases (89%) was seen in those under 1 yr (who would have been directly affected by vaccination) with case numbers falling to 59 from a mean 537 cases in the equivalent period for 2004-2013. Initially data suggests a 92% reduction in 2015 compared to the same pre-vaccination periods. For those aged 1 to <5 y who would not have been vaccinated, a reduction of 75% was also evident in 2014 and 77% in 2015, suggesting indirect protection in this group. In conclusion, initial results following the introduction of the Rotavirus vaccine clearly indicates a very good uptake of the vaccine and a significant reduction in the numbers of laboratory confirmed cases.

Association of Maternal Immunity with Rotavirus Vaccine Immunogenicity in Zambian Infants

Introduction

Live attenuated oral vaccines against rotavirus (RV) have been shown to be less efficacious in children from developing countries. Reasons for this disparity are not fully understood. We assessed the role of maternal factors including breast milk RV-specific IgA, transplacentally acquired infant serum RV-specific IgG and maternal HIV status in seroconversion among Zambian infants routinely immunized with Rotarix™ (RV1).

Methods

420 mother-child pairs were recruited at infant age 6–12 weeks in Lusaka. Clinical information and samples were collected at baseline and at one month following the second dose of RV1. Determination of breast milk RV-specific IgA and serum RV-specific IgA and IgG was done using standardized ELISA. Seroconversion was defined as a ≥ 4 fold rise in serum IgA titre from baseline to one-month post RV1 dose 2, while seropositivity of IgA was defined as serum titre ≥ 40 and antibody variables were modelled on log-base 2. Logistic regression was used to identify predictors of the odds of seroconversion.

Results

Baseline infant seropositivity was 25.5% (91/357). The seroconversion frequency was 60.2% (130/216). Infants who were IgA seropositive at baseline were less likely to seroconvert compared to their seronegative counterparts (P = 0.04). There was no evidence of an association between maternal HIV status and seroconversion (P = 0.25). Higher titres of breast milk rotavirus-specific IgA were associated with a lower frequency of seroconverson (Nonparametric test for trend Z = -2.84; P<0.01): a two-fold increase in breast milk RV-specific IgA titres was associated with a 22% lower odds of seroconversion (OR = 0.80; 95% CI = 0.68–0.94; P = 0.01). There was seasonal variation in baseline breast milk rotavirus-specific IgA titres, with significantly higher GMTs during the cold dry months (P = 0.01).

Conclusion

Low immunogenicity of RV1 vaccine could be explained in part by exposure to high antibody titres in breast milk and early exposure to wild-type rotavirus infections. Potential interference of anti-RV specific IgA in breast milk and pre-vaccination serum RV specific-IgA and IgG titres with RV1 seroconversion and effectiveness requires further research.

Beyond efficacy: The full public health impact of vaccines

There is an active discussion in the public health community on how to assess and incorporate, in addition to safety and measures of protective efficacy, the full public health value of preventive vaccines into the evidence-based decision-making process of vaccine licensure and recommendations for public health use. The conference "Beyond efficacy: the full public health impact of vaccines in addition to efficacy measures in trials" held in Annecy, France (June 22-24, 2015) has addressed this issue and provided recommendations on how to better capture the whole public health impact of vaccines. Using key examples, the expert group stressed that we are in the midst of a new paradigm in vaccine evaluation, where all aspects of public health value of vaccines beyond efficacy should be evaluated. To yield a wider scope of vaccine benefits, additional measures such as vaccine preventable disease incidence, overall efficacy and other outcomes such as under-five mortality or non-etiologically confirmed clinical syndromes should be assessed in addition to traditional efficacy or effectiveness measurements. Dynamic modelling and the use of probe studies should also be considered to provide additional insight to the full public health value of a vaccine. The use of burden reduction and conditional licensure of vaccines based on collection of outcome results should be considered by regulatory agencies.

Public health impact of accelerated immunization against rotavirus infection among children aged less than 6 months in the United States

We developed a cohort model to evaluate the expected public health impact of accelerated regimens for immunization against rotavirus gastroenteritis (RVGE). Alternative strategies for vaccination with the pentavalent human-bovine reassortant vaccine, Rotateq^® (RV5, Merck) and the oral live attenuated human rotavirus vaccine, Rotarix^® (RV1, GlaxoSmithKline Vaccines) were considered, including acceleration of the 1st dose only (by 2 weeks) as well as acceleration of the 1st (by 2 weeks) and subsequent doses (by up to 10 weeks). Assuming vaccine coverage levels consistent with current US clinical practice, accelerated regimens would be expected to reduce annual numbers of RVGE-related hospitalizations by 300–400, emergency department visits by 3000–4000, and outpatient visits by 3000–4000 (i.e., by 9–14%) among US children aged <6 months. Accordingly, accelerating the immunization of children against RVGE may yield substantive reductions in the number of RV-related encounters in US clinical practice.

Safety and Immunogenicity of Sequential Rotavirus Vaccine Schedules

BACKGROUND AND OBJECTIVES

Although both licensed rotavirus vaccines are safe and effective, it is often not possible to complete the schedule by using the same vaccine formulation. The goal of this study was to investigate the noninferiority of the immune responses to the 2 licensed rotavirus vaccines when administered as a mixed schedule compared with administering a single vaccine formulation alone.

METHODS

Randomized, multicenter, open-label study. Healthy infants (6-14 weeks of age) were randomized to receive rotavirus vaccines in 1 of 5 different schedules (2 using a single vaccine for all doses, and 3 using mixed schedules). The group receiving only the monovalent rotavirus vaccine received 2 doses of vaccine and the other 4 groups received 3 doses of vaccine. Serum for immunogenicity testing was obtained 1 month after the last vaccine dose and the proportion of seropositive children (rotavirus immunoglobulin A ≥20 U/mL) were compared in all the vaccine groups.

RESULTS

Between March 2011 and September 2013, 1393 children were enrolled and randomized. Immune responses to all the sequential mixed vaccine schedules were shown to be noninferior when compared with the 2 single vaccine reference groups. The proportion of children seropositive to at least 1 vaccine antigen at 1 month after vaccination ranged from 77% to 96%, and was not significantly different among all the study groups. All schedules were well tolerated.

CONCLUSIONS

Mixed schedules are safe and induced comparable immune responses when compared with the licensed rotavirus vaccines given alone.

Cost-effectiveness analysis of the introduction of rotavirus vaccine in Iran

BACKGROUND

Although the mortality from diarrheal diseases has been decreasing dramatically in Iran, it still represents an important proportion of disease burden in children <5 years old. Rotavirus vaccines are among the most effective strategies against diarrheal diseases in specific epidemiological conditions. This study aimed to evaluate the cost-effectiveness of the introduction of rotavirus vaccine (3 doses of pentavalent RotaTeq (RV5)) in Iran, from the viewpoints of Iran's health system and society.

METHODS

The TRIVAC decision support model was used to calculate total incremental costs, life years (LYs) gained, and disability-adjusted life years (DALYs) averted due to the vaccination program. Necessary input data were collected from the most valid accessible sources as well as a systematic review and meta-analysis on epidemiological studies. We used WHO guidelines to estimate vaccination cost. An annual discount rate of 3% was considered for both health gain and costs. A deterministic sensitivity analysis was performed for testing the robustness of the models results.

RESULTS

Our results indicated that total DALYs potentially lost due to rotavirus diarrhea within 10 years would be 138,161, of which 76,591 could be prevented by rotavirus vaccine. The total vaccination cost for 10 cohorts was estimated to be US$ 499.91 million. Also, US$ 470.61 million would be saved because of preventing outpatient visits and inpatient admissions (cost-saving from the society perspective). We estimated a cost per DALY averted of US$ 2868 for RV5 vaccination, which corresponds to a highly cost-effective strategy from the government perspective. In the sensitivity analysis, all scenarios tested were still cost-saving or highly cost-effective from the society perspective, except in the least favorable scenario and low vaccine efficacy and disease incidence scenario.

CONCLUSION

Based on the findings, introduction of rotavirus vaccine is a highly cost-effective strategy from the government perspective. Introducing the vaccine to the national immunization program is an efficient use of available funds to reduce child mortality and morbidity in Iran.

Medium- to Long-Term Impact of Rotavirus Vaccination on Hospital Care in Belgium: A 7-Year Follow-Up of the Rotavirus Belgium Impact Study (RotaBIS)

Introduction

Rotavirus (RV) vaccination was introduced in Belgium in 2006. With the high uptake it had (>85%), a sharp decline in hospitalizations was observed during the first years after vaccine introduction. The objective of this study was to investigate whether this decline was maintained and to simulate projections.

Methods

The Rotavirus Belgium Impact Study allowed an analysis of the RV vaccine impact amongst children in 11 hospitals in Belgium over a 9-year period (2005–2013) with 2 years pre- and 7 years post-vaccine introduction. Results were compared by year and by subsequent birth cohort aging up to 5 years. The two different analysis methods helped dismantling the different (direct and indirect) effects of vaccine protection to simulate future hospitalization trends.

Results

During the whole observation period, 40,552 RV detection tests were performed of which 5832 were positive (14.4%). After RV vaccine introduction, a significant reduction in number of tests performed (−38%) was combined with a dramatic drop in numbers of positive tests (−76.6%). The decreases were spectacular during the first two years of vaccine introduction; after that period, the decrease flattened. Cross-sectional comparison with cohort data showed that the initial drop was heavily influenced by the herd effect of the vaccine. Cohort analysis demonstrated a low rate of residual disease over time, suggesting another infection source other than the child population.

Conclusion

The residual disease will be maintained in the community when a same vaccination strategy is continued over time, starting vaccination of children only at 6 weeks’ time.

Funding

GlaxoSmithKline Biologicals SA.

Trial registration

ClinicalTrials.gov identifier, NCT01563146.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-015-0099-1) contains supplementary material, which is available to authorized users.

Molecular characterisation of wild-type G1P[8] and G3P[8] rotaviruses isolated in Vietnam 2008 during a vaccine trial

Rotavirus vaccines work better in developed countries than in developing countries, leading to the question of whether the circulating strains are different in these two settings. In 2008, a clinical trial of the pentavalent rotavirus vaccine was performed in Nha Trang, Vietnam, in which the efficacy was reported to be 64 %. Although samples were collected independently from the clinical trial, we examined faecal specimens from children hospitalised for rotavirus diarrhoea and found that G3P[8] and G1P[8] were co-dominant at the time of the clinical trial. The aim of this study was to explore whether they were divergent from the strains circulating in the developed countries where the vaccine efficacy is high. Two G3P[8] and two G1P[8] strains that were regarded as representatives based on their electropherotypes were selected for full-genome sequencing. The genotype constellation was G1/G3-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1. All but the VP4 genes, one of which belonged to the emerging P[8]b genotype (OP354-like VP4), clustered into one or more lineages/alleles with the strains circulating in developed countries, with ≥97.5 % nucleotide sequence identity. Additionally, 10 G1 and 12 G3 VP7 sequences as well as 31 VP4 sequences were determined. No amino acid differences were observed between the Vietnamese strains and strains in the developed countries that were likely to have affected the neutralisation specificity of their VP7 and VP4. In conclusion, apart from prevalent P[8]b VP4, virtually no differences were observed between the predominant strains circulating in Vietnam at the time of the clinical trial and the strains in the developed countries; hence, the lower vaccine efficacy was more likely to be due to factors other than strain divergence.

Vaccines for viral and bacterial pathogens causing acute gastroenteritis: Part I: Overview, vaccines for enteric viruses and Vibrio cholerae

Efforts to develop vaccines for prevention of acute diarrhea have been going on for more than 40 y with partial success. The myriad of pathogens, more than 20, that have been identified as a cause of acute diarrhea throughout the years pose a significant challenge for selecting and further developing the most relevant vaccine candidates. Based on pathogen distribution as identified in epidemiological studies performed mostly in low-resource countries, rotavirus, Cryptosporidium, Shigella, diarrheogenic E. coli and V. cholerae are predominant, and thus the main targets for vaccine development and implementation. Vaccination against norovirus is most relevant in middle/high-income countries and possibly in resource-deprived countries, pending a more precise characterization of disease impact. Only a few licensed vaccines are currently available, of which rotavirus vaccines have been the most outstanding in demonstrating a significant impact in a short time period. This is a comprehensive review, divided into 2 articles, of nearly 50 vaccine candidates against the most relevant viral and bacterial pathogens that cause acute gastroenteritis. In order to facilitate reading, sections for each pathogen are organized as follows: i) a discussion of the main epidemiological and pathogenic features; and ii) a discussion of vaccines based on their stage of development, moving from current licensed vaccines to vaccines in advanced stage of development (in phase IIb or III trials) to vaccines in early stages of clinical development (in phase I/II) or preclinical development in animal models. In this first article we discuss rotavirus, norovirus and Vibrio cholerae. In the following article we will discuss Shigella, Salmonella (non-typhoidal), diarrheogenic E. coli (enterotoxigenic and enterohemorragic), and Campylobacter jejuni.

Emergence of Rotavirus G12P[8] in St. Louis During the 2012-2013 Rotavirus Season

BACKGROUND

We observed an increase in the number of rotavirus cases in the St. Louis area during the 2012-2013 rotavirus season compared with recent seasons. We aimed to determine whether the rotavirus cases during the 2012-2013 rotavirus season were of types not included in licensed vaccines.

METHODS

Microbiology laboratories of 3 children's hospitals in St. Louis provided samples that were positive using rapid antigen tests from 2010 to 2013. The majority of samples were from St. Louis Children's Hospital. We determined rotavirus genotypes by polymerase chain reaction tests and further characterized a subset of viruses by genome sequencing and comparative sequence analysis.

RESULTS

Eighty-six percent (24 of 28) of typed viruses analyzed from the 2012-2013 rotavirus season were G12. We performed whole genome sequencing on 8 G12 viruses, all of which were VP4 type P[8]. The sequenced viruses showed differences from vaccine strains in major antigenic epitopes on the VP7 protein, but most epitopes on VP4 were conserved. Rotavirus vaccine histories were available for 11 G12 cases, of whom 10 had not been vaccinated.

CONCLUSIONS

G12 was a dominant community-wide genotype in 2013. Most of the G12 cases for whom vaccine histories were available had not received rotavirus vaccine. The experience demonstrates the potential for rapid shifts in rotavirus genotype distribution and underscores the need for vigilant surveillance to detect unusual genotypes that might escape from vaccine protection.

Current status of rotavirus vaccines

BACKGROUND

Rotaviruses remain the major cause of childhood diarrheal disease worldwide and of diarrheal deaths of infants and children in developing countries. The huge burden of childhood rotavirus-related diarrhea in the world continues to drive the remarkable pace of vaccine development.

DATA SOURCES

Research articles were searched using terms "rotavirus" and "rotavirus vaccine" in MEDLINE and PubMed. Articles not published in the English language, articles without abstracts, and opinion articles were excluded from the review. After preliminary screening, all articles were reviewed and synthesized to provide an overview of current vaccines and vaccination programs.

RESULTS

In this review of the global rotavirus vaccines and vaccination programs, the principles of rotavirus vaccine development and the efficacy of the currently licensed vaccines from both developed and developing countries were summarized.

CONCLUSIONS

Rotavirus is a common cause of diarrhea in children in both developed and developing countries. Rotavirus vaccination is a cost-effective measure to prevent rotavirus diarrhea.

Correlates of protection for rotavirus vaccines: Possible alternative trial endpoints, opportunities, and challenges

Rotavirus (RV) is a major vaccine-preventable killer of young children worldwide. Two RV vaccines are globally commercially available and other vaccines are in different stages of development. Due to the absence of a suitable correlate of protection (CoP), all RV vaccine efficacy trials have had clinical endpoints. These trials represent an important challenge since RV vaccines have to be introduced in many different settings, placebo-controlled studies are unethical due to the availability of licensed vaccines, and comparator assessments for new vaccines with clinical endpoints are very large, complex, and expensive to conduct. A CoP as a surrogate endpoint would allow predictions of vaccine efficacy for new RV vaccines and enable a regulatory pathway, contributing to the more rapid development of new RV vaccines. The goal of this review is to summarize experiences from RV natural infection and vaccine studies to evaluate potential CoP for use as surrogate endpoints for assessment of new RV vaccines, and to explore challenges and opportunities in the field.

Knowledge, attitudes, beliefs, and behaviors of parents and healthcare providers before and after implementation of a universal rotavirus vaccination program

OBJECTIVE

In Canada, rotavirus vaccine is recommended for all infants, but not all provinces/territories have publicly funded programs. We compared public and healthcare provider (HCP) knowledge, attitudes, beliefs, and behaviors in a province with a public health nurse-delivered, publicly funded rotavirus vaccination program to a province with a publicly funded, physician-delivered program. A third province with no vaccination program acted as a control.

DESIGN

Information about knowledge, attitudes, beliefs, and behaviors of parents whose children were eligible for the universal program and healthcare providers responsible for administering the vaccine were collected through the use of two validated surveys distributed in public health clinics, physicians' offices, and via e-mail. Early and postvaccine-program survey results were compared.

RESULTS

A total of 722 early implementation and 709 postimplementation parent surveys and 180 early and 141 postimplementation HCP surveys were analyzed. HCP and public attitudes toward rotavirus vaccination were generally positive and didn't change over time. More parents postprogram were aware of the NACI recommendation and the vaccination program and reported that their healthcare provider discussed rotavirus infection and vaccine with them. Prior to the program across all sites, more physicians than nurses were aware of the national recommendation regarding rotavirus vaccine. In the postprogram survey, however, more nurses were aware of the national recommendation and their provincial universal rotavirus vaccination program. Nurses had higher knowledge scores than physicians in the postprogram survey (p<0.001). Parents of young infants were also more knowledgeable about rotavirus and rotavirus vaccine in the two areas where universal programs were in place (p<0.001).

CONCLUSIONS

Implementation of a universal rotavirus vaccination program was associated with an increase in knowledge and more positive attitudes toward rotavirus vaccine amongst parents of eligible infants. Nurses involved in a public health-delivered vaccination program were more knowledgeable and had more positive attitudes toward the vaccine than physicians in a jurisdiction where vaccine was physician-delivered.