Preparing for safety monitoring after rotavirus vaccine introduction - Assessment of baseline epidemiology of intussusception among children <2 years of age in four Asian countries

Characterisation of a G2P[4] Rotavirus Outbreak in Western Australia, Predominantly Impacting Aboriginal Children

In May, 2017, an outbreak of rotavirus gastroenteritis was reported that predominantly impacted Aboriginal children ≤4 years of age in the Kimberley region of Western Australia. G2P[4] was identified as the dominant genotype circulating during this period and polyacrylamide gel electrophoresis revealed the majority of samples exhibited a conserved electropherotype. Full genome sequencing was performed on representative samples that exhibited the archetypal DS-1-like genome constellation: G2-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2 and phylogenetic analysis revealed all genes of the outbreak samples were closely related to contemporary Japanese G2P[4] samples. The outbreak samples consistently fell within conserved sub-clades comprised of Hungarian and Australian G2P[4] samples from 2010. The 2017 outbreak variant was not closely related to G2P[4] variants associated with prior outbreaks in Aboriginal communities in the Northern Territory. When compared to the G2 component of the RotaTeq vaccine, the outbreak variant exhibited mutations in known antigenic regions; however, these mutations are frequently observed in contemporary G2P[4] strains. Despite the level of vaccine coverage achieved in Australia, outbreaks continue to occur in vaccinated populations, which pose challenges to regional areas and remote communities. Continued surveillance and characterisation of emerging variants are imperative to ensure the ongoing success of the rotavirus vaccination program in Australia.

Epidemiology of Hospitalized Intussusception Cases from Northern States in India

OBJECTIVE

To describe epidemiology of intussusception post-introduction of the rotavirus vaccine.

METHODS

Hospital-based active surveillance system was set up in three tertiary care hospitals in Chandigarh and Haryana, India, to enroll children <2 y of age admitted with intussusception as per Brighton Collaboration Level-I criteria. The clinical characteristics, treatment modalities, seasonal trends, and outcome of the illness episodes were described.

RESULTS

A total of 224 cases were reported. Majority were males (71%) and infants (69.5%). Number of intussusception was more in summer season. Location of intussusception was ileo-colic in 85% of the cases. Nearly 54% cases were treated conservatively and 46% needed surgical intervention.

CONCLUSION

Surveillance data provided the epidemiological description of intussusception cases post-introduction of the rotavirus vaccine in northern India. This data could be used to assess the impact of vaccine and safety with a special focus on intussusception.

Epidemiology of intussusception among children less than 2 years of age; findings from baseline surveillance before rotavirus vaccine introduction in Myanmar

BACKGROUND

Rotavirus vaccine was planned to be introduced in the National Immunization Program of Myanmar in 2020. Reported potential association of a small increased risk of intussusception after rotavirus vaccination in some countries is a major safety concern and it is mandatory to collect baseline information before vaccine introduction.

METHODS

Retrospective study reviewed medical records of intussusception cases for past 3 years (2015-2018) and prospective, active study was conducted from August 2018 to January 2020 at three tertiary children hospitals where pediatric surgical facility is present. Brighton Level 1 Criteria was used for confirmation of intussusception among children <2 years of age admitted to surgical wards. Demographic, clinical, diagnostic and treatment practices data were collected and descriptive data analysis was performed.

RESULTS

A total of 697 (421 in retrospective and 276 in prospective) confirmed intussusception cases were identified. Majority of intussusception cases (550/697, 78.9%) were observed in the first year of life and most frequent between 5-7 months of age (292/697, 41.9%) with a peak at 6 months (114/697, 16.4%). The most common clinical presentations were vomiting and bloody diarrhea accounting 82.1% and 77.5% respectively. Regarding diagnosis and treatment, 458/697 (65.7%) required surgical intervention either manual reduction or intestinal resection and 34.4% by either air or barium enema. Overall mortality was 0.7% (5/697) and four out of five children died needed intestinal resection. Late arrival to hospital (>3days after onset) is significantly associated with requirement of surgery (61/85, 71.8%), which in turn is significantly associated with longer hospital stay (296/452, 65.5%) (p < 0.05).

CONCLUSIONS

Intussusception occurrence is most frequent between 5-7 months age group which is old enough to be vaccinated under the schedule that has now been introduced in Myanmar. More than half of the cases were treated by surgery and late arrival to hospital enhances requirement of surgery and poor outcome. Findings of this baseline surveillance provide important facts for public health officials in balancing risks and benefits of rotavirus vaccine introduction, defining targeted age and dosage scheduling and facilitate monitoring system in post-vaccination.

Evaluation of the safety profile of rotavirus vaccines: a pharmacovigilance analysis on American and European data

Rotaviruses (RVs) are the most common cause of severe diarrheal disease. To date two rotavirus oral vaccines are licensed: Rotarix and Rotateq. Our aim was to contribute to the post-marketing evaluation of these vaccines safety profile. We collected all RV vaccines-related reports of Adverse Events Following Immunization (AEFI) in US Vaccine Adverse Events Reporting System (VAERS) and VigiBase between January 2007 and December 2017. A disproportionality analysis using Reporting Odds Ratio (ROR) was performed. A total of 17,750 reports in VAERS and 6,358 in VigiBase were retrieved. In VAERS, 86.2% of the reports concerned RotaTeq, whereas in VigiBase 67.7% of them involved Rotarix. Across the databases, diarrhea (1,672 events in VAERS, 1,961 in VigiBase) and vomiting (1,746 in VAERS, 1,508 in VigiBase) were the most reported AEFIs. Noteworthy, the RV vaccines-intussusception pair showed a ROR greater than 20 in both databases. Some new potential safety signals emerged such as fontanelle bulging, hypotonic-hyporesponsive episode, livedo reticularis, and opisthotonus. Overall, our data show that most of the reported AEFIs are listed in the Summary of Product Characteristics (SPCs). However, there remains the need to investigate the potential safety signals arose from this analysis, in order to complete the description of the AEFIs.

Current and new rotavirus vaccines

As of 2019, four rotavirus vaccines have been prequalified by the WHO for use worldwide. This review highlights current knowledge regarding rotavirus vaccines available, and provides a brief summary of the rotavirus vaccine pipeline.

Infectious Etiologies of Intussusception Among Children <2 Years Old in 4 Asian Countries

BACKGROUND

The etiology of intussusception, the leading cause of bowel obstruction in infants, is unknown in most cases. Adenovirus has been associated with intussusception and slightly increased risk of intussusception with rotavirus vaccination has been found. We conducted a case-control study among children <2 years old in Bangladesh, Nepal, Pakistan, and Vietnam to evaluate infectious etiologies of intussusception before rotavirus vaccine introduction.

METHODS

From 2015 to 2017, we enrolled 1-to-1 matched intussusception cases and hospital controls; 249 pairs were included. Stool specimens were tested for 37 infectious agents using TaqMan Array technology. We used conditional logistic regression to estimate odds ratio (OR) and 95% confidence interval (CI) of each pathogen associated with intussusception in a pooled analysis and quantitative subanalyses.

RESULTS

Adenovirus (OR, 2.67; 95% CI, 1.75-4.36) and human herpes virus 6 (OR, 3.50; 95% CI, 1.15-10.63) were detected more frequently in cases than controls. Adenovirus C detection <20 quantification cycles was associated with intussusception (OR, 18.59; 95% CI, 2.45-140.89). Wild-type rotavirus was not associated with intussusception (OR, 1.07; 95% CI, 0.52-2.22).

CONCLUSIONS

In this comprehensive evaluation, adenovirus and HHV-6 were associated with intussusception. Future research is needed to better understand mechanisms leading to intussusception, particularly after rotavirus vaccination.