Intussusception Rates Before and After the Introduction of Rotavirus Vaccine

Progress in research and development of preventive vaccines for children in China

The infant and child stage is an important stage for the continuation and development of human society. The initial years of life have a lasting impact on a child's future. Children under the age of 5 have an immature immune system, especially infants and young children under 6 months of age. At this stage, the population has a low immunity to pathogen infections, making them vulnerable to bacteria and viruses. Vaccination can enhance the immunity of infants and children to specific diseases, reduce the transmission rate of infectious diseases, and promote the development of global public health. This article summarizes the current application status of Rotavirus (RV) vaccine, Hand-foot -mouth disease (HFMD) vaccine, and Pneumococcal Conjugate Vaccine (PCV) in China, as well as the research progress of clinical trial vaccine, laying a foundation for subsequent vaccine development.

Two cases of small bowel necrosis due to intussusception secondary to abnormal proliferation of intestinal Peyer's patches in infants after MMR vaccination

BACKGROUND

Intussusception is one of the most common acute abdominal conditions in pediatric patients, and if left untreated, it may result in intestinal necrosis and even death. The etiology of the disease is unknown and may be related to a variety of factors, and there are only limited reports of small bowel necrosis secondary to abnormal Peyer's node hyperplasia after MMR vaccination.

CASE PRESENTATION

In this report, we present two infants who had an abnormal proliferation of Peyer's nodes secondary to intussusception eventually leading to small bowel necrosis after MMR vaccination.

CONCLUSIONS

Intestinal necrosis and infectious shock are the most common causes of infant mortality, and early detection and management are critical.

Self-controlled risk interval study of rotavirus vaccine safety: Findings and implications

BACKGROUND

The self-controlled case series (SCCS) is often used to monitor vaccine safety. The evaluation of intussusception after the rotavirus vaccine is complicated because the baseline rate varies with age. Time-varying baseline risk adjustments with data from unexposed cohorts are utilised. Self-controlled risk interval (SCRI), with a shorter observation period, can also mitigate the problem by studying a control period close to the risk period.

OBJECTIVE

An Indian rotavirus vaccine has previously been studied using SCCS. The risk of intussusception in the high-risk windows (21 days after vaccination) was comparable to the background risk. The aim was to re-analyse data of an existing SCCS study using alternate statistical methods to examine vaccine safety.

METHODS

We examined the mean age of intussusception in the vaccinated and the unvaccinated. We performed an SCRI analysis of the surveillance data from the SCCS study, limiting the observation period to 180 days. We analysed the time-to-intussusception from the last vaccination. Finally, we performed an SCCS analysis, excluding unvaccinated cases from the analysis.

RESULTS

We found that the mean age of intussusception was significantly lower in the vaccinated (205 days) compared to the unvaccinated (223 days) (p-value 0.0026). The Incident Risk Ratio (IRR) on SCRI analysis was 1.62 (95% CI 1.07-2.44). There were significantly more intussusceptions in the first 30 days after vaccination compared to the next 30-day window. (92 vs 63 p-value = 0.009). We found that excluding unvaccinated infants from the SCCS analysis demonstrated significantly increased risk for the risk period 1-21 days after the 3rd dose (IRR 2.47, 95% CI 1.70-3.59). The risks of intussusception were missed in traditional SCCS analysis using unvaccinated infants as controls.

CONCLUSION

Traditional risk adjustments using data from unexposed cohorts in SCCS may not be appropriate for investigating the risk of intussusception where vaccination lowers the mean age of intussusception.

Clinical characteristics of pediatric intussusception and predictors of bowel resection in affected patients

Background

Surgery is required for the treatment of intussusception when enema reduction is unsuccessful, or when the patient develops peritonitis, bowel perforation, or intestinal damage. We aimed to evaluate the clinical and laboratory parameters that may be used to predict the need for bowel resection in children with intussusception.

Methods

This observational retrospective study included children who were admitted to the pediatric emergency department with intussusception. Univariate and multivariate logistic regression models were used to evaluate factors associated with bowel resection.

Results

In total, 584 children with intussusception were admitted to the pediatric emergency department; 129 of these children underwent surgery. Multivariate analysis revealed the following independent predictors of bowel resection for intussusception: symptoms for at least 2 days before surgery (OR = 6.863; p = 0.009), long intussusception (OR = 5.088; p = 0.014), pathological lead point (OR = 6.926; p = 0.003), and intensive care unit admission (OR = 11.777; p = 0.001) were factors independently associated with bowel resection.

Conclusion

Symptoms for at least 2 days before surgery, long intussusception, pathological lead, and intensive care unit admission were predictors of bowel resection in children with intussusception. These findings can be used to identify patients at high risk of needing surgery and bowel resection.

COVID-19-Related Intussusception: A Case Series and Review of the Literature

Background: Ileocolic intussusception is a common gastrointestinal emergency that occurs in infancy. Many cases are caused by anatomic lead points, such as hypertrophied Peyer's patches. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, which causes coronavirus disease 2019 (COVID-19), commonly presents with respiratory symptoms, however, its relation to intussusception remains unknown. Methods: Two cases are reported as well as a review of pertinent English-language literature on the topic. Results: We present two cases of intussusception in COVID-19-positive patients, including the first known case of a lead point with tissue polymerase chain reaction (PCR) confirming COVID-19 positivity, and compare these findings to a review of the recent literature. Intussusception in COVID-19-positive patients is becoming more prevalent and more often requires operative treatment. Discussion: We offer evidence that intussusception can be the presenting symptom in the absence of COVID-19-related respiratory symptoms. There also seems to be a trend toward the need for operative intervention compared with COVID-19-negative intussusception. The presence of SARS-CoV-2 can be confirmed via PCR in specific lead points (lymph nodes), directly causing the intussusception. Conclusions: Providers should have a low threshold to suspect and diagnose intussusception as operative treatment is more readily used in COVID-19-positive pediatric patients with gastrointestinal symptoms.

Review of Over 15 Years Postmarketing Safety Surveillance Spontaneous Data for the Human Rotavirus Vaccine (Rotarix) on Intussusception

Introduction

Rotavirus (RV) is the most common cause of acute gastroenteritis in children <5 years of age worldwide, and vaccination reduces the disease burden. Evidence from postmarketing surveillance studies suggested an increased risk of intussusception (IS) in infants post-RV vaccination. An overall positive benefit–risk balance for the human RV vaccine (HRV) Rotarix (GlaxoSmithKline [GSK], Belgium) has been established and recent findings indicate an indirect effect of reduced IS over the long term.

Objective

The aim of this study was to discuss spontaneous data from the GSK worldwide safety database on IS post-Rotarix administration.

Methods

The database was reviewed for all spontaneous IS cases from 2004 to 2020. Additionally, an observed versus expected (O/E) analysis was done for adverse events attributed to IS. Data were reviewed as overall worldwide and stratified by region (Europe/USA/Japan) and dose.

Results

A male predominance of IS patients was observed, consistent with earlier reports. The most frequently reported events in confirmed IS cases (Brighton Collaboration Working Group [BCWG] level 1) with time to onset ≤ 30 days post-vaccination were vomiting (55.8%), haematochezia (47.2%), and crying (21.1%). The observations from the IS spontaneous cases review and results of the O/E analysis are consistent with the known IS safety profile of RV vaccines: a transient increased incidence of IS post-vaccination (primarily in Europe/Japan/worldwide), mostly within 7 days postdose 1.

Conclusion

Since the outcomes of early IS management are favourable over delayed management, healthcare professionals should inform parents about the importance of seeking immediate medical advice in case of unusual behaviour of the vaccinated infant. GSK continues to monitor the IS risk post-Rotarix administration through routine pharmacovigilance activities.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40264-021-01141-4.

Rotavirus (RV) is the most common cause of acute gastroenteritis and a major cause of death in young children worldwide. Vaccination has been instrumental in reducing the impact of RV disease. Real-world evidence suggests an increased risk of intussusception (an infrequent type of bowel obstruction) in infants following RV vaccination. We reviewed IS cases reported spontaneously worldwide in children following a two-dose vaccination with the human RV vaccine (Rotarix, GlaxoSmithKline [GSK]) since its launch in 2004. We observed that (1) IS occurred more frequently 7 days after the first dose and, to a lesser extent, after the second dose; (2) boys were more frequently affected than girls (56.3%); (3) of 862 confirmed reported cases, 557 required hospitalisation; and (4) surgical intervention was required for 294 of 557 hospitalised cases. We used statistical analysis to assess whether the number of cases observed would be higher or lower than the natural occurrence of IS (irrespective of vaccination). These results were in line with the known RV vaccine safety profile. It is important to constantly monitor the real-world safety profile of RV vaccines in the postmarketing setting. Since the outcomes of early management of IS are favourable compared with delayed management, healthcare professionals should inform parents to seek immediate medical advice if they observe unusual behaviour in their vaccinated child. In conclusion, our analyses on data of a large patient pool for this rare event reinforce the favourable safety profile of human RV vaccine and the benefits of vaccination in young children.

Epidemiology of intussusception among infants in Togo, 2015-2018

Introduction

intussusception is the leading cause of bowel obstruction in infants and young children. We describe the epidemiology and diagnostic and treatment characteristics of intussusception among Togolese infants over a 4-year period.

Methods

we implemented active surveillance among infants younger than 1 year of age admitted with intussusception from 2015 to 2018 at Sylvanus Olympio Teaching Hospital and in 2018 at Campus Teaching Hospital. Brighton Collaboration Level 1 case definition criteria were used to confirm the diagnosis of intussusception.

Results

during four years, 41 cases of intussusception, with an annual range of 8 to 14 cases (median: 10) were reported; and the highest number of cases (89%) was enrolled at Sylvanus Olympio teaching hospital. Intussusception was uncommon in the first 2 months of life, peaked from 5 to 7 months old (63%), with male predominance (63%), and showed no significant seasonality. One third of cases (34%) were transferred to the sentinel surveillance site from another health facility; and the median delay in seeking care was 4 days (range: 0-11) with ≥ 48-hour delay in 59% of cases. Clinical symptoms, ultrasound and surgery were combined to diagnose intussusception in all the cases (100%). The treatment was exclusively surgical, and intestinal resection was common (28/41, 68%). A high case fatality rate (23%) was observed and the average length of hospital stay was 10 days (range: 1-23).

Conclusion

active surveillance for intussusception in Togo has highlighted exclusive use of surgical therapy; often associated to an intestinal resection with a very high case fatality rate.

Rotavirus vaccination impact, Ireland, implications for vaccine confidence and screening

BACKGROUND

Rotavirus vaccine efficacy is well established. However, it is important to consistently demonstrate the positive impact of vaccination programmes in order to optimize uptake rates and combat vaccine hesitancy.

METHODS

Routine data were used to examine rotavirus vaccine effectiveness in Ireland, including changes in age-specific crude incidence rates (CIRs), hospitalizations and hospital length of stay. National intussusception incidence was interrogated. Vaccination status of vaccine-eligible cases of rotavirus infection was determined.

RESULTS

Nationally, a reduction in the CIR of rotavirus infection of 77.2% [95% confidence interval (CI) 57.8-88.5%, P<0.001] was observed post-inclusion of the rotavirus vaccine in the primary immunization schedule. A decrease in hospitalizations of 85.5% (95% CI 79.3-90.2%, P<0.001), 86.5% (95% CI 82.9-89.4%, P<0.001) and 78.5% (95% CI 74.7-81.9%, P<0.001) was observed in children aged <1, <2 and <5 years, respectively. Most hospitalizations occurred in infants too young to have been vaccinated. There was no significant difference in median length of stay for children hospitalized with rotavirus infection. Decreased CIRs and hospitalization rates in unvaccinated children aged between 2 and 5 years suggest community immunity. Vaccine non-protection was 0.13%. No increase in the national CIR of intussusception was observed.

CONCLUSIONS

Inclusion of the rotavirus vaccine in the Irish primary immunization schedule has resulted in a significant reduction in the burden of rotavirus infection. However, vaccine hesitancy remains a concern. With new vaccination programmes, risk of vaccine harms should be considered and mitigated in order to protect individuals and the integrity of the programme.

Safety of vaccines used for routine immunization in the United States: An updated systematic review and meta-analysis

BACKGROUND

Understanding the safety of vaccines is critical to inform decisions about vaccination. Our objective was to conduct a systematic review of the safety of vaccines recommended for children, adults, and pregnant women in the United States.

METHODS

We searched the literature in November 2020 to update a 2014 Agency for Healthcare Research and Quality review by integrating newly available data. Studies of vaccines that used a comparator and reported the presence or absence of key adverse events were eligible. Adhering to Evidence-based Practice Center methodology, we assessed the strength of evidence (SoE) for all evidence statements. The systematic review is registered in PROSPERO (CRD42020180089).

RESULTS

Of 56,603 reviewed citations, 338 studies reported in 518 publications met inclusion criteria. For children, SoE was high for no increased risk of autism following measles, mumps, and rubella (MMR) vaccine. SoE was high for increased risk of febrile seizures with MMR. There was no evidence of increased risk of  intussusception with rotavirus vaccine at the latest follow-up (moderate SoE), nor of diabetes (high SoE). There was no evidence of increased risk or insufficient evidence for key adverse events for newer vaccines such as 9-valent human papillomavirus and meningococcal B vaccines. For adults, there was no evidence of increased risk (varied SoE) or insufficient evidence for key adverse events for the new adjuvanted inactivated influenza vaccine and recombinant adjuvanted zoster vaccine. We found no evidence of increased risk (varied SoE) for key adverse events among pregnant women following tetanus, diphtheria, and acellular pertussis vaccine, including stillbirth (moderate SoE).

CONCLUSIONS

Across a large body of research we found few associations of vaccines and serious key adverse events; however, rare events are challenging to study. Any adverse events should be weighed against the protective benefits that vaccines provide.

Novel vaccine safety issues and areas that would benefit from further research

Vaccine licensure requires a very high safety standard and vaccines routinely used are very safe. Vaccine safety monitoring prelicensure and postlicensure enables continual assessment to ensure the benefits outweigh the risks and, when safety problems arise, they are quickly identified, characterised and further problems prevented when possible. We review five vaccine safety case studies: (1) dengue vaccine and enhanced dengue disease, (2) pandemic influenza vaccine and narcolepsy, (3) rotavirus vaccine and intussusception, (4) human papillomavirus vaccine and postural orthostatic tachycardia syndrome and complex regional pain syndrome, and (5) RTS,S/adjuvant system 01 malaria vaccine and meningitis, cerebral malaria, female mortality and rebound severe malaria. These case studies were selected because they are recent and varied in the vaccine safety challenges they elucidate. Bringing these case studies together, we develop lessons learned that can be useful for addressing some of the potential safety issues that will inevitably arise with new vaccines.

Childhood Intussusception after Introduction of Indigenous Rotavirus Vaccine: Hospital-Based Surveillance Study from Odisha, India

OBJECTIVE

To study the epidemiology of intussusception in children < 2 y of age, postintroduction of Rotavac® (an indigenous oral rotavirus vaccine).

METHODS

A multicenter hospital-based surveillance was conducted in Odisha from February 2016 to June 2019. The cases were diagnosed according to Brighton level-1 criteria. Data were collected regarding the time of onset, signs and symptoms, radiological diagnosis, management, complications, and outcome (discharged/died).

RESULTS

One hundred and twenty children < 2 y of age were enrolled. The median age was 7 mo (M:F ratio = 2:1). The most common clinical feature was abdominal distention and blood in stool. The most common method for treatment was hydrostatic/pneumatic reduction. Median time (days) between symptom onset and admission was 2. Median (IQR) duration (days) of hospitalization was 5. Most common location of intussusceptions was ileo-colic.

CONCLUSIONS

Hydrostatic/pneumatic reduction was possible in the majority presenting ≤ 48 h of symptom onset, and those presenting > 48 h mostly required surgical reduction. Intestinal resection was required in some cases presenting on day 5 of symptom onset. Majority of cases were managed by surgical reduction in Government facility.

Surgery and Resource Utilization Trends for Pediatric Intussusception From 2005 Through 2014

BACKGROUND

Air or barium enema reduction is becoming increasingly common and safer for pediatric intussusception. However, little is known about trends of pediatric intussusception requiring surgical intervention in the United States.  Methods: National Inpatient Sample database was analyzed from 2005-2014 to identify pediatric (≤18 years) intussusceptions along with procedures such as enema and/or surgical intervention. Trends in the rates of surgical intervention were examined according to encounter-level (age, gender, race, comorbidities) and hospital-level (hospital census region, teaching status) characteristics. Outcomes of pediatric intussusception requiring surgical intervention were analyzed in terms of length of stay and cost of hospitalization. Factors associated with surgical intervention were also analyzed. P value of < 0.05 was considered significant.  Results: Out of 21,835 intussusception hospitalizations requiring enema or surgical intervention, 14,415 (66%) had surgical intervention; 90% of which (12,978) had no preceding enema. Surgical intervention rates among intussusception hospitalizations varied by age (highest < 1 year), gender (male > females) and race (Hispanics > Whites and Blacks). During the study period, overall surgical intervention rate remained stable (2.2 to 1.7, P=0.07) although it declined in those under 1 year of age. Children with severe disease, gastrointestinal comorbidities over the age of 4 years had increased odds of surgical intervention, whereas hospitalization in large and urban teaching hospitals had decreased odds of surgical intervention. Length of stay and hospital cost remained stable from 2005-2014.

CONCLUSION

The rates of surgical intervention and resource utilization for pediatric intussusception remained stable from 2005-2014, however they declined significantly in infants. The proportion of intussusception hospitalization requiring surgery remains high and further studies are needed to explore the possible factors.

Association between rotavirus vaccination and intussusception in Australian children: A record linkage study

BACKGROUND

Post-licensure surveillance studies have shown a small but increased risk of intussusception among infants in the days following rotavirus vaccination (RV).

OBJECTIVES

We assessed the temporal trends of intussusception-coded hospitalisations before and after the commencement of a universal rotavirus vaccination programme in Western Australia (WA) in 2007. We also assessed the perinatal factors and pathogens associated with these hospitalisations.

METHODS

Intussusception-coded hospitalisations occurring in a cohort of 367 476 WA-born children (2000-2012) aged <5 years were probabilistically linked to perinatal and pathology records. Age-specific incidence rates for overall and pathogen-specific intussusception-coded hospitalisations were calculated before (2000-2006) and after (2008-2012) RV introduction. Adjusted Cox proportional hazards models were used to assess perinatal risk factors for intussusception.

RESULTS

The overall rate of intussusception-coded hospitalisation was 26.4 per 100 000 child-years (95% confidence interval [CI] 24.0, 29.0) among children aged <5 years, with rates being 70% higher (95% CI 39, 107) in the RV period than in the pre-RV period. Compared with the pre-RV period, rates were higher among those aged 12-23 months (by 55%, 95% CI 5, 127) and 2-4 years (by 84%, 95% CI 20, 182) in the RV period. However, the risk of intussusception-coded hospitalisations associated with intussusception management-related procedure code(s) was similar among all age groups in both birth periods. Among infants aged <12 months, male sex, non-Aboriginal status, birth to multiparous mothers, and birth in RV era were independent risk factors associated with intussusception-coded hospitalisations. Adenovirus was strongly associated with intussusception (6.7 per 100 000 child-years, 95% CI 5.3, 9.3).

CONCLUSIONS

The risk of intussusception-coded hospitalisations was higher post-RV introduction, but not for intussusception-coded hospitalisations associated with procedure code(s). The increase was no higher in the vaccine-eligible age group than in older age groups, suggesting that the apparent increase is likely to be attributable to causes other than vaccination.

Incidence of intussusception before and after the introduction of rotavirus vaccine in Korea

Background

Recent studies have reported that after the introduction of rotavirus vaccine the incidence of intussusception did not change among infants, or slightly increased at the age immediately after the first dose. The rotavirus vaccines were introduced in Korea for private market use in 2007–2008. We investigated the incidence of intussusception before (2002–2006) and after (2009–2015) the vaccine introduction in Korea.

Methods

We conducted an interrupted time series study that used data from the Korean National Health Insurance database to identify infants (<12 months of age) who were diagnosed with intussusception and underwent non-invasive or invasive reduction from 2002 to 2015. According to the recommended ages for immunization, the annual intussusception incidence and the incidence rate ratios were calculated among three age groups, 6–14, 15–24, and 25–34 weeks.

Results

The annual incidences in infants have decreased over time from 241.7 per 100,000 infants (pre-vaccine period) to 160.1–205.2 per 100,000 infants (post-vaccine period). The incidence rate ratio during the post-vaccine period ranged from 0.66 to 0.85. The incidences of intussusception in all three infant age groups have decreased in post-vaccine period compared to pre-vaccine period (incidence rate ratio range: 0.31–0.65, 0.47–0.75, and 0.68–0.94 in 6–14, 15–24, and 25–34 weeks, respectively).

Conclusions

The incidence of intussusception in infants did not increase after the rotavirus vaccine introduction in Korea, but rather decreased over the past decades. Since the incidence of intussusception varies according to country or region, continuous monitoring the incidence of intussusception in infants is necessary in each county or region.

Association between rotavirus gastroenteritis and intussusception: suggested evidence from a retrospective study in claims databases in the United States

The etiology of intussusception (IS), a serious gastrointestinal obstruction, remains unclear. Limited evidence suggests a role for viral infection. We investigated the risk of IS after rotavirus gastroenteritis (RV GE) in the first year of life. In this retrospective, self-controlled case series (SCCS), we assessed the risk of IS after RV GE using data from United States administrative claims databases. Incidence rate ratios (IRR) of IS were calculated for the 7- and 21-day risk periods after RV GE (main analysis) or after fracture (sensitivity analysis). A total of 290,912,068 subjects were screened; 42 presented claims for RV GE and IS, and 66 for fracture and IS. The IRRs of IS after RV GE were 79.6 (95% confidence interval, CI: 38.6-164.4) and 25.5 (95% CI: 13.2-49.2) in the 7- and 21-day risk periods. The sensitivity analysis showed an association between IS and fracture for both periods, suggesting potential confounding. Post-hoc analyses did not confirm the association between fracture and IS but suggested a potential association between RV GE and IS. A temporal association between RV GE and IS was detected using claims databases. Due to some limitations of the data sources, this association should be further investigated.

Rotavirus vaccination and intussusception: a paradigm shift?

Rotavirus (RV) is one of the leading causes of severe childhood gastroenteritis in children <5 years of age. Several countries have successfully implemented vaccination against RV disease; however, hesitancy to include RV vaccination in the national immunization program exists and relates, among other reasons, to the results of international post-licensure studies of RV vaccines that established an increased risk of intussusception (IS) in infants following immunization. IS is one of the major causes of bowel obstruction in infants between 4 and 10 months of age. Some studies have investigated the etiology of IS, including the role of natural RV infection and available evidence suggests that RV disease may be an independent risk factor for IS. In this regard, the benefit-risk profile of RV vaccination, which is recognized as positive, could potentially turn out to be even more favorable in preventing IS cases triggered by RV disease. However, further research is prompted to quantify the IS risk attributable to RV disease.

Does Rotavirus Vaccination Affect Longer-Term Intussusception Risk in US Infants?

Rotavirus vaccination has been associated with a short-term increased risk of intussusception. Our analysis of insurance claims for 1 858 827 US children with 544 recorded cases of intussusception found a nonsignificant decrease in intussusception (hazard ratio, 0.79 [95% confidence interval, 0.57-1.09]) in fully rotavirus-vaccinated children followed up to the age of 2 years.

Rotavirus vaccines in clinical development: Current pipeline and state-of-the-art

Rotavirus (RV) disease is a leading cause of mortality and morbidity, especially in children under 5 years of age. The introduction of the two oral rotavirus vaccines Rotarix^® and RotaTeq^® has shown significant reductions in RV-related mortality, severe RV disease, and hospitalizations. However, some barriers, including a reduced efficacy in low-income countries, safety issues regarding the intussusception risk, age restrictions on vaccine use, the live-attenuated nature itself, and the substantial vaccine costs, currently restrict the full potential of RV disease prevention. Therefore, research is now focusing on the implementation of new oral vaccines and the development of parenteral vaccines to overcome these limits. This review provides an overview of the new rotavirus vaccines in clinical development and the ongoing clinical trials on new RV vaccines in the pediatric age.

Genetic characterization of group-A rotaviruses among children in eastern India during 2014-2016: Phylodynamics of co-circulating genotypes

BACKGROUND

Group-A human rotaviruses (GARV) are among the major cause of childhood diarrhea worldwide. In lieu of monitoring the circulatory GARV strains and underscoring the burden of GARV related hospitalization, a systematic surveillance was conducted in three hospitals of eastern India. In this hospital-based diarrheal disease surveillance (2014-2016), GARV was the most common cause of acute infantile gastroenteritis. The strains were genotyped and characterized to understand their prevalence and phylodynamics prior to the introduction of vaccine in eastern India.

MATERIALS AND METHODS

A total of 3652 stool samples were screened from children (≤5 years) hospitalized with acute diarrhea during 2014-2016. Initial screening for VP6 antigen was done by ELISA. GARV positive samples were genotyped by multiplex semi-nested PCR and DNA sequencing and phylogenetic analyses were based on the capsid proteins VP4 and VP7.

RESULTS

Of 3652 samples, 1817 (49.8%) were GARV positive. G1, G2, G3 and G9 in conjunction with P[4], P[6]and P[8]genotypes were seen to co-circulate in the population. A sharp deflection from G1 to G3 occurred since 2016; upsurge of G9 strains was seen in alternate years, whereas G2 strains had a low frequency. All the circulating genotypes depicted a low phylogenetic relatedness to the vaccine strains. Differences in antigenic epitopes of VP4 and VP7 proteins in local strains were seen when compared to the vaccine strains. A significant difference in the degree of dehydration, duration of mean hospital stay and frequency of vomiting/24 h between GARV positive and negative children was evident.

CONCLUSION

The study provides a relevant set of base-line data on high burden of rotaviral gastroenteritis and the varied genotypic diversity among children prior to the introduction of GARV vaccine in this endemic region. Continuous monitoring during post-vaccination era will be required to assess the impact of vaccination in this region.

Missed Opportunities for Rotavirus Vaccination

BACKGROUND

Rotavirus remains an important cause of gastroenteritis and has been associated with the hospitalization of 34 to 53 per 10 000 children <5 years of age in the United States annually from 2008 to 2012. Rotavirus vaccines are underused compared with other routine vaccines. We describe rotavirus vaccine coverage and missed opportunities for rotavirus vaccination.

METHODS

The National Immunization Survey is a random-digit-dial, population-based survey including US children 19 to 35 months of age. Children fully vaccinated for rotavirus were those who received 3 doses of the pentavalent rotavirus vaccine, 2 doses of the monovalent rotavirus vaccine, or ≥3 doses of either vaccine type. Doses of the diphtheria-tetanus-acellular pertussis vaccine received from 6 weeks through 8 months and 0 days of age when the rotavirus vaccine was not received were considered missed opportunities for rotavirus vaccination according to Advisory Committee on Immunization Practices (ACIP) guidelines, and doses of the diphtheria-tetanus-acellular pertussis vaccine or measles-mumps-rubella vaccine from 6 weeks through 24 months and 0 days of age were considered missed opportunities according to World Health Organization recommendations.

RESULTS

Of the 14 571 children included in the 2014 National Immunization Survey, 71% were fully vaccinated for rotavirus. Lower socioeconomic status increased the likelihood of being unvaccinated for rotavirus. Among the 14% of children who received no doses of the rotavirus vaccine, 72% had ≥1 ACIP-defined missed opportunities, and 83% had ≥1 World Health Organization-defined missed opportunities. Higher socioeconomic status increased the likelihood of having missed opportunities. Complete rotavirus vaccine coverage could be improved to 81% if all missed opportunities within the ACIP-recommended schedule were addressed.

CONCLUSIONS

Addressing missed opportunities for rotavirus vaccination is essential to achieving the 80% rotavirus vaccine coverage target outlined by Healthy People 2020.

Intussusception Rate Among Under-Five-Children Before Introduction of Rotavirus Vaccine in North India

BACKGROUND

Baseline data on intussusception are needed to compare the intussusception rates following introduction of rotavirus vaccine.

METHODS

A hospital-based bidirectional surveillance (retrospective from 2009 to 2012; and prospective from 2013 to 2015) was set up in a tertiary care hospital in Chandigarh, India, to enrol children <5 years of age admitted with intussusception as per Brighton's classification, to estimate the hospital admission rate. Incidence of intussusception among infants and children <5 years of age was also estimated.

RESULTS

A total of 277 intussusception cases (96 retrospective; 181 prospective) were reported. Majority of cases were males (69.7%) and infants (72%). Median age at diagnosis was 10 months (interquartile range 6-12 months). Nearly 62% cases were treated surgically and 33% radiologically. Incidence was estimated to be 20/100 000 infants, and 5/100 000 children <5 years of age per year, in Chandigarh.

CONCLUSION

Intussusception surveillance system provided background hospital admission and incidence rate before rotavirus vaccine introduction in North India.

Epidemiology of intussusception before and after rotavirus vaccine introduction in Fiji

In 2012, Fiji introduced rotavirus vaccine (Rotarix, GSK) into the national immunisation schedule. We describe the intussusception epidemiology prior to rotavirus vaccine, temporal association of intussusception cases to administration of rotavirus vaccine, and estimate the additional number of intussusception cases that may be associated with rotavirus vaccine. A retrospective review of intussusception cases for children aged <24 months old was undertaken between January 2007 and October 2012 pre-vaccine. All admissions and deaths with a discharge diagnosis of intussusception, bowel obstruction, paralytic ileus, or intussusception ICD10-AM codes were extracted from national databases and hospital records. Nationwide active intussusception surveillance was established for three years post-vaccine (2013–2015). There were 24 definite intussusception cases in the pre-rotavirus vaccine period, 96% were confirmed by surgery. The median age was 6.5 months. The incidence rate was 22.2 (95% CI: 13.9–33.7) per 100,000 infants. There were no deaths. Active surveillance identified 25 definite intussusception cases, 96% of which were among children who were age-eligible for rotavirus vaccine. None were potentially vaccine related. We estimated one to five additional  cases of intussusception every five years. The incidence of intussusception pre-rotavirus vaccine in Fiji is low. Intussusception associated with rotavirus vaccine is likely a rare event in Fiji.

A benefit-risk analysis of rotavirus vaccination, France, 2015

Two vaccines available for protection against rotavirus gastroenteritis (RVGE), Rotarix and RotaTeq, have contributed to a large decrease in the incidence of paediatric diarrhoea in countries where they have been used. However, they have also led to a small increase in the risk of intussusception. Methods: We compare the number of prevented hospitalisations for RVGE to the number of vaccine-induced hospitalised intussusceptions in France. Results: With 9.5% coverage (French 2015 estimation), vaccination was estimated to prevent, annually, a median of 1,074 hospitalisations (2.5th and 97.5th percentiles (2.5th–97.5th): 810–1,378) and 1.4 deaths (2.5th–97.5th: 1.2–1.6) from RVGE. It was also estimated to cause, annually, 5.0 hospitalisations (2.5th–97.5th: 3.2–7.7) and 0.005 deaths (2.5th–97.5th: 0.001–0.015) from intussusception. The benefit–risk ratio is therefore 214 (2.5th–97.5th: 128–362) for hospitalisations and 273 (2.5th–97.5th: 89–1,228) for deaths. Under a hypothetical 92% coverage, rotavirus vaccination with Rotarix would avoid 10,459 (2.5th–97.5th: 7,702–13,498) hospitalisations for RVGE and induce 47.0 (2.5th–97.5th: 25.1–81.4) hospitalisations for intussusception annually, thereby preventing 13.7 (2.5th–97.5th: 11.1–15.2) deaths and inducing 0.05 (2.5th–97.5th: 0.01–0.15) deaths. Conclusion: The benefit–risk ratio in France is similar to that of other European countries.

Recurrent intussusception among infants less than 2 years of age in Vietnam

In some settings, rotavirus vaccines have been associated with a low-level risk of intussusception, the most common cause of bowel obstruction in infants. As Vietnam prepares to introduce rotavirus vaccine into the national immunization program, we sought to better characterize the epidemiology of recurrent intussusception. We enrolled children <2 years of age who were hospitalized for intussusception retrospectively from January 2013 through December 2014 and prospectively from January 2015 through December 2016 at 2 hospitals in Vietnam. We enrolled 2477 children. Nearly all children were successfully treated by enema with low surgery rate (1%). We found 10% of children (n = 254) experienced at least once recurrence (range: 1-6) and 57% of first recurrences happened within the first 12 weeks after treatment of the first episode. The median age at first intussusception was 13 months for children without a recurrent episode and 10 months for children with a recurrence. The symptoms of the recurrent cases were milder with less vomiting (67%), bloody stool (7%) and fever (10%) compared to the initial cases (p < 0.01). We found the rate of recurrences following enema reduction of intussusception to be similar to that reported from other countries. Due to the high rate of intussusception and recurrent episodes in Vietnam, a better understanding of the cause of recurrent intussusception will be critical in assessing intussusception cases after rotavirus introduction.

Report of the 5th European expert meeting on rotavirus vaccination (EEROVAC)

The Fifth European Expert Meeting on Rotavirus Vaccination was convened in Utrecht, The Netherlands, in March 2017. The 2-day meeting included invited lectures as well as original oral and poster presentations and brought together experts from 21 countries. Summary findings of the meeting include: Rotavirus vaccination programmes in Europe have resulted in reductions of 60–90% in rotavirus outpatient visits and hospitalizations. Long term trends indicate this impact is sustained over the years. Herd effects, protecting unvaccinated children and neonates too young to be vaccinated have been observed in many European countries. Early evidence now also suggests that rotavirus vaccination may be instrumental in the prevention of celiac disease. Special attention should be given to preterm infants, who may age out of the vaccination window before hospital discharge and to HIV infected children who are at increased risk of severe rotavirus AGE. There is a small but increased risk of IS following rotavirus vaccination and parents should therefore be informed about possible signs and symptoms of IS. New insights in rotavirus genetic susceptibility and interactions with microbiome may open opportunities for interventions to improve protection by vaccination, in particular in LMIC. The development of several novel rotavirus vaccines discussed at the meeting is also promising in this respect.

Rotavirus infection

Rotavirus infections are a leading cause of severe, dehydrating gastroenteritis in children <5 years of age. Despite the global introduction of vaccinations for rotavirus over a decade ago, rotavirus infections still result in >200,000 deaths annually, mostly in low-income countries. Rotavirus primarily infects enterocytes and induces diarrhoea through the destruction of absorptive enterocytes (leading to malabsorption), intestinal secretion stimulated by rotavirus non-structural protein 4 and activation of the enteric nervous system. In addition, rotavirus infections can lead to antigenaemia (which is associated with more severe manifestations of acute gastroenteritis) and viraemia, and rotavirus can replicate in systemic sites, although this is limited. Reinfections with rotavirus are common throughout life, although the disease severity is reduced with repeat infections. The immune correlates of protection against rotavirus reinfection and recovery from infection are poorly understood, although rotavirus-specific immunoglobulin A has a role in both aspects. The management of rotavirus infection focuses on the prevention and treatment of dehydration, although the use of antiviral and anti-emetic drugs can be indicated in some cases.