Broad spectrum SARS-CoV-2-specific immunity in hospitalized First Nations peoples recovering from COVID-19.

Indigenous peoples globally are at increased risk of COVID-19-associated morbidity and mortality. However, data that describe immune responses to SARS-CoV-2 infection in Indigenous populations are lacking. We evaluated immune responses in Australian First Nations peoples hospitalized with COVID-19. Our work comprehensively mapped out inflammatory, humoral and adaptive immune responses following SARS-CoV-2 infection. Patients were recruited early following the lifting of strict public health measures in the Northern Territory, Australia, between November 2021 and May 2022. Australian First Nations peoples recovering from COVID-19 showed increased levels of MCP-1 and IL-8 cytokines, IgG-antibodies against Delta-RBD and memory SARS-CoV-2-specific T cell responses prior to hospital discharge in comparison with hospital admission, with resolution of hyperactivated HLA-DR+ CD38+ T cells. SARS-CoV-2 infection elicited coordinated ASC, Tfh and CD8+ T cell responses in concert with CD4+ T cell responses. Delta and Omicron RBD-IgG, as well as Ancestral N-IgG antibodies, strongly correlated with Ancestral RBD-IgG antibodies and Spike-specific memory B cells. We provide evidence of broad and robust immune responses following SARS-CoV-2 infection in Indigenous peoples, resembling those of non-Indigenous COVID-19 hospitalized patients.

Sydenham chorea in the top end of Australia's Northern Territory: A 20-year retrospective case series.

AIM: Sydenham chorea is an immune-mediated neuropsychiatric condition, and a major criterion for diagnosis of acute rheumatic fever (ARF). Children in remote Northern Australia experience disproportionately high rates of ARF, yet studies looking at the epidemiology, clinical presentation and management of Sydenham chorea are limited in this population. METHODS: We conducted a retrospective case series from January 2002 to April 2022 of all paediatric patients aged ≤18 years admitted to Royal Darwin Hospital with Sydenham chorea. Cases were identified using the hospital's clinical coding system (ICD10). Medical records were reviewed and data on demographics, clinical presentation, investigation results, treatment and outcome were extracted, deidentified and analysed. RESULTS: One hundred ten presentations of Sydenham chorea occurred between 2002 and 2022, 109 (99%) of these were in First Nations children, with 85% residing in very remote locations. Most commonly, chorea presented as a generalised movement disorder affecting all four limbs (49%). Neuropsychiatric symptoms were reported in 33 (30%), and there was evidence of rheumatic heart disease on echocardiogram in 86 (78%) at presentation. All patients received benzathine penicillin, but there was significant variation in management of chorea, ranging from supportive management, to symptomatic management with anticonvulsants, to immunomodulatory medications including corticosteroids. CONCLUSION: This case series highlights the significant burden of Sydenham chorea among First Nations children living in Northern Australia and demonstrates wide variation in treatment approaches. High-quality clinical trials are required to determine the best treatment for this disabling condition.

Histo-blood group antigen profile of Australian Aboriginal children and seropositivity following oral rotavirus vaccination.

BACKGROUND: Histo-blood group antigens (HBGAs) may influence immune responses to rotavirus vaccination. METHODS: HBGA phenotyping was determined by detection of antigens A, B, H and Lewis a and b in saliva using enzyme-linked immunosorbent assay. Secretor status was confirmed by lectin antigen assay if A, B and H antigens were negative or borderline (OD ± 0.1 of threshold of detection). PCR-RFLP analysis was used to identify the FUT2 'G428A' mutation in a subset. Rotavirus seropositivity was defined as serum anti-rotavirus IgA ≥ 20 AU/mL. RESULTS: Of 156 children, 119 (76 %) were secretors, 129 (83 %) were Lewis antigen positive, and 105 (67 %) were rotavirus IgA seropositive. Eighty-seven of 119 (73 %) secretors were rotavirus seropositive, versus 4/9 (44 %) weak secretors and 13/27 (48 %) non-secretors. CONCLUSIONS: Most Australian Aboriginal children were secretor and Lewis antigen positive. Non-secretor children were less likely to be seropositive to rotavirus antibodies following vaccination, but this phenotype was less common. HBGA status is unlikely to fully explain underperformance of rotavirus vaccines among Australian Aboriginal children.

Robust and prototypical immune responses toward COVID-19 vaccine in First Nations peoples are impacted by comorbidities.

High-risk groups, including Indigenous people, are at risk of severe COVID-19. Here we found that Australian First Nations peoples elicit effective immune responses to COVID-19 BNT162b2 vaccination, including neutralizing antibodies, receptor-binding domain (RBD) antibodies, SARS-CoV-2 spike-specific B cells, and CD4+ and CD8+ T cells. In First Nations participants, RBD IgG antibody titers were correlated with body mass index and negatively correlated with age. Reduced RBD antibodies, spike-specific B cells and follicular helper T cells were found in vaccinated participants with chronic conditions (diabetes, renal disease) and were strongly associated with altered glycosylation of IgG and increased interleukin-18 levels in the plasma. These immune perturbations were also found in non-Indigenous people with comorbidities, indicating that they were related to comorbidities rather than ethnicity. However, our study is of a great importance to First Nations peoples who have disproportionate rates of chronic comorbidities and provides evidence of robust immune responses after COVID-19 vaccination in Indigenous people.

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.

Systematic review of the effect of additional doses of oral rotavirus vaccine on immunogenicity and reduction in diarrhoeal disease among young children.

Background: Oral rotavirus vaccines have lower effectiveness in high child mortality settings. We evaluated the impact of additional dose(s) schedules of rotavirus vaccine on vaccine immunogenicity and reduction in episodes of gastroenteritis. Methods: We searched Medline (via PubMed), Cochrane databases and ClinicalTrials.gov for randomised controlled trials from 1973 to February 2022, evaluating the immunological and clinical impact of additional dose vs standard dose oral rotavirus vaccine schedules. We extracted immunogenicity - proportion of children with evidence of anti-rotavirus IgA seroresponse, and clinical - proportion of children with at least one episode of severe rotavirus gastroenteritis, outcome data and used random effects meta-analysis where appropriate. We assessed the methodological quality of the studies using the Cochrane risk of bias tool. The study protocol was registered in PROSPERO (CRD42021261058). Findings: We screened 536 items and included 7 clinical trials. Our results suggest moderate to high level evidence that an additional dose rotavirus vaccine schedule improves IgA vaccine immune response, including additional doses administered as a booster dose schedule >6 months old; IgA vaccine seroresponse 74·3% additional dose schedule vs 56·1% standard dose schedule RR 1·3 (95%CI, 1·15 - 1·48), and when administered to children who were seronegative at baseline; IgA vaccine seroresponse 48.2% additional dose schedule vs 29.6% standard dose schedule RR 1.86 (95%CI 1.27 to 2.72). Only one study evaluated reduction in gastroenteritis episodes and found little benefit in first year of life, 1·8% vs 2·0% RR 0·88 (95% CI, 0·52 to 1·48), or second year of life, 1·7% vs 2·9% RR 0·62 (95%CI, 0·31 - 1·23). Interpretation: Administering an additional dose of oral rotavirus vaccines is likely to result in an improved vaccine immune response, including when administered as a booster dose to older children. Evidence of an impact on diarrhoeal disease is needed before additional dose rotavirus vaccine schedules can be recommended as vaccine policy. Funding: BM was funded by the National Health and Medical Research Council, the Royal Australasian College of Physicians Paediatrics and Child Health Division, and the Australian Academy of Science.

Immunogenicity of a Third Scheduled Dose of Rotarix in Australian Indigenous Infants: A Phase IV, Double-blind, Randomized, Placebo-Controlled Clinical Trial.

BACKGROUND: Rotarix (GlaxoSmithKline) oral rotavirus vaccine is licensed as 2 doses in the first 6 months of life. In settings with high child mortality rates, clinical protection conferred by 2 doses of Rotarix is reduced. We assessed vaccine immune response when an additional dose of Rotarix was given to Australian Aboriginal children 6 to <12 months old. METHODS: ORVAC is a 2-stage, double-blind, randomized, placebo-controlled trial. Australian Aboriginal children 6 to <12 months old who had received 1 or 2 prior doses of Rotarix rotavirus vaccine were randomized 1:1 to receive an additional dose of Rotarix or matched placebo. The primary immunological end point was seroresponse defined as an anti-rotavirus immunoglobulin A level ≥20 AU/mL, 28-56 days after the additional dose of Rotarix or placebo. RESULTS: Between March 2018 and August 2020, a total of 253 infants were enrolled. Of these, 178 infants (70%) had analyzable serological results after follow-up; 89 were randomized to receive Rotarix, and 89 to receive placebo. The proportion with seroresponse was 85% after Rotarix compared with 72% after placebo. There were no occurrences of intussusception or any serious adverse events. CONCLUSIONS: An additional dose of Rotarix administered to Australian Aboriginal infants 6 to <12 months old increased the proportion with a vaccine seroresponse. CLINICAL TRIALS REGISTRATION: NCT02941107.

Retrospective Case-Control Study of 2017 G2P[4] Rotavirus Epidemic in Rural and Remote Australia.

BACKGROUND: A widespread G2P[4] rotavirus epidemic in rural and remote Australia provided an opportunity to evaluate the performance of Rotarix and RotaTeq rotavirus vaccines, ten years after their incorporation into Australia's National Immunisation Program. METHODS: We conducted a retrospective case-control analysis. Vaccine-eligible children with laboratory-confirmed rotavirus infection were identified from jurisdictional notifiable infectious disease databases and individually matched to controls from the national immunisation register, based on date of birth, Aboriginal status and location of residence. RESULTS: 171 cases met the inclusion criteria; most were Aboriginal and/or Torres Strait Islander (80%) and the median age was 19 months. Of these cases, 65% and 25% were fully or partially vaccinated, compared to 71% and 21% of controls. Evidence that cases were less likely than controls to have received a rotavirus vaccine dose was weak, OR 0.79 (95% CI, 0.46-1.34). On pre-specified subgroup analysis, there was some evidence of protection among children <12 months (OR 0.48 [95% CI, 0.22-1.02]), and among fully vs. partially vaccinated children (OR 0.65 [95% CI, 0.42-1.01]). CONCLUSION: Despite the known effectiveness of rotavirus vaccination, a protective effect of either rotavirus vaccine during a G2P[4] outbreak in these settings among predominantly Aboriginal children was weak, highlighting the ongoing need for a more effective rotavirus vaccine and public health strategies to better protect Aboriginal children.