Perinatal Risk Factors Associated With Gastroenteritis Hospitalizations in Aboriginal and Non-Aboriginal Children in Western Australia (2000-2012): A Record Linkage Cohort Study

Review of the health impact of the oral rotavirus vaccine program in children under 5 years in Australia: 2006 - 2021

Oral rotavirus vaccines were incorporated into the National Immunisation Program (NIP) for all Australian infants in July 2007. Initially each of the eight jurisdictions implemented Rotarix or RotaTeq rotavirus vaccine, however from July 2017 all states and territories have administered Rotarix only. This review evaluates the health impact of the oral rotavirus vaccine program for Australian children less than 5 years old over the first 15 years of the rotavirus vaccine program, observing long-term changes in rotavirus-related health care attendances, public health notifications, and vaccine effectiveness and safety data for both Rotarix and RotaTeq rotavirus vaccines. We searched Medline for studies published between January 2006 and May 2022 using the search terms 'rotavirus', 'rotavirus vaccine' and 'Australia'. Of 491 items identified, 76 items - 36 peer-reviewed articles and 40 reports - were included in the review. We found evidence that the introduction of the oral rotavirus vaccine program in Australia was associated with a prompt reduction in rotavirus-coded and all-cause gastroenteritis hospitalisations of vaccine-eligible children. In the context of less complete coverage, reduced vaccine timeliness and lower vaccine effectiveness, a less substantial and inconsistent reduction in severe rotavirus disease was observed among Aboriginal and Torres Strait Islander children, particularly those living in rural and remote northern Australia. Additional studies report no evidence for the emergence of non-vaccine serotypes and/ or replacement serotypes in Australia during the vaccine era. While the health impact for young children and consequent cost-savings of the oral rotavirus vaccine program have been high, it is important to find strategies to improve rotavirus vaccine impact for Aboriginal and Torres Strait Islander populations to ensure health benefits for all Australian children.

Impact of Rotavirus Vaccines on Gastroenteritis Hospitalizations in Western Australia: A Time-series Analysis

Background

Rotavirus vaccination was introduced into the Australian National Immunisation Program in mid-2007. We aimed to assess the impact of the rotavirus vaccination program on the burden of hospitalizations associated with all-cause acute gastroenteritis (including rotavirus gastroenteritis and non-rotavirus gastroenteritis) in the Aboriginal and non-Aboriginal population in Western Australia.

Methods

We identified all hospital records, between July 2004 and June 2012, with a discharge diagnosis code for all-cause gastroenteritis. Age-specific hospitalization rates for rotavirus and non-rotavirus acute gastroenteritis before and after the introduction of the rotavirus vaccination program were compared. Interrupted time-series models were used to examine differences in the annual trends of all-cause gastroenteritis hospitalization between the two periods.

Results

Between July 2004 and June 2012, there were a total of 106,974 all-cause gastroenteritis-coded hospitalizations (1,381 rotavirus-coded [15% among Aboriginal] and 105,593 non-rotavirus gastroenteritis-coded [7% among Aboriginal]). Following rotavirus vaccination introduction, significant reductions in rotavirus-coded hospitalization rates were observed in all children aged <5 years (up to 79% among non-Aboriginal and up to 66% among Aboriginal). Among adults aged ≥65 years, rotavirus-coded hospitalizations were 89% (95% confidence interval, 16–187%) higher in the rotavirus vaccination program period. The time-series analysis suggested reductions in all-cause gastroenteritis hospitalizations in the post-vaccination period among both vaccinated and unvaccinated (age-ineligible) children, with increases observed in adults aged ≥45 years.

Conclusions

Rotavirus vaccination has been associated with a significant decline in gastroenteritis hospitalizations among children. The increase in the elderly requires further evaluation, including assessment of the cost-benefits of rotavirus vaccination in this population.

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.

Perinatal risk factors associated with skin infection hospitalisation in Western Australian Aboriginal and Non-Aboriginal children

BACKGROUND

Hospitalisation with skin infection in Western Australian (WA) Aboriginal children is common, with the highest rates in infants and children from remote WA.

OBJECTIVE

We aimed to quantify infant, maternal, and sociodemographic risk factors for skin infection hospitalisation in WA children, focussing on Aboriginal children aged <17 years.

METHODS

We conducted a retrospective population-based cohort study with linked perinatal and hospitalisation data on WA-born children (1996-2012), of whom 31 348 (6.7%) were Aboriginal. We used Cox regression to calculate adjusted hazard ratios and associated population attributable fractions (PAFs) for perinatal factors attributed to first hospitalisation with skin infection. To identify specific risk factors for early-onset infection, we further restricted the cohort to infants aged <1 year.

RESULTS

Overall, 5439 (17.4%) Aboriginal and 6750 (1.5%) non-Aboriginal children were hospitalised at least once with a skin infection. Aboriginal infants aged <1 year had the highest skin infection hospitalisation rate (63.2 per 1000 child-years). The strongest risk factors in Aboriginal children aged <17 years were socio-economic disadvantage, very remote location at birth, and multi-parity (≥3 previous pregnancies) accounting for 24%, 23%, and 15% of skin infection hospitalisations, respectively. Other risk factors included maternal age <20 years, maternal smoking during pregnancy, and low birthweight.

CONCLUSIONS

We have quantified the relative influence of perinatal risk factors associated with skin infection hospitalisations in WA children, providing measures indicating which factors have the potential to reduce the most hospitalisations. Our evidence not only supports existing calls for substantial government investment in addressing underlying social and environmental barriers to healthy skin in WA Aboriginal children but also identifies potential areas to target health promotion messaging at individuals/families on maternal smoking during pregnancy and skin hygiene for families.