RESUMEN
INTRODUCTION: Intussusception is the primary cause of acute bowel obstruction in infants. The majority of cases under 2 years of age are classed as idiopathic with viral infection implicated as one of the causes. COVID-19 public health measures led to significant decreases in communicable disease prevalence. During these times, reductions in intussusception frequency were reported - reductions greater than would be expected with our previous understanding of its infectious aetiology. METHODS: We conducted a retrospective, multi-state, ecological study over a twelve-year period. Monthly case numbers of ICD-10-AM K56.1 'Intussusception' coded admissions were acquired from state-wide admissions datasets from New South Wales (NSW), Victoria and Queensland, representing 77.62% of the eligible Australian population. These counts within differing jurisdictional lockdowns were compared to non-lockdown periods in order to investigate a correlation between intussusception frequency and lockdown periods. RESULTS: We found a negative association between intussusception frequency and lockdown periods in both eligible states. The largest reductions were seen in the under 2 year age groups with Victoria experiencing a 62.7% reduction (Rate ratio (RR) = 0.37, p < 0.0001) and NSW a 40.1% reduction (RR = 0.599, p = 0.006) during lockdown times. Controls for variations in lockdown restrictions between both regional and metropolitan areas also showed expected decreases. CONCLUSION: Our ecological study demonstrates significant decreases in the frequency of paediatric intussusception admissions during the COVID-19 lockdown periods. The unexpected magnitude of the reductions suggests that the true proportion of infectious disease-caused idiopathic intussusception is greatly underestimated.
RESUMEN
Acute Disseminated Encephalomyelitis (ADEM) and Transverse Myelitis (TM) are within the group of immune mediated disorders of acquired demyelinating syndromes. Both have been described in temporal association following various vaccinations in case reports and case series and have been evaluated in observational studies. A recent analysis conducted by The Global Vaccine Data Network (GVDN) observed an excess of ADEM and TM cases following the adenoviral vectored ChAdOx1 nCoV-19 (AZD1222) and mRNA-1273 vaccines, compared with historically expected background rates from prior to the pandemic. Further epidemiologic studies were recommended to explore these potential associations. We utilized an Australian vaccine datalink, Vaccine Safety Health-Link (VSHL), to perform a self-controlled case series analysis for this purpose. VSHL was selected for this analysis as while VSHL data are utilised for GVDN association studies, they were not included in the GVDN observed expected analyses. The VSHL dataset contains vaccination records sourced from the Australian Immunisation Register, and hospital admission records from the Victorian Admitted Episodes Dataset for 6.7 million people. These datasets were used to determine the relative incidence (RI) of G040 (ADEM) and G373 (TM) ICD-10-AM coded admissions in the 42-day risk window following COVID-19 vaccinations as compared to control periods either side of the risk window. We observed associations between ChAdOx1 adenovirus vector COVID-19 vaccination and ADEM (all dose RI: 3.74 [95 %CI 1.02,13.70]) and TM (dose 1 RI: 2.49 [95 %CI: 1.07,5.79]) incident admissions. No associations were observed between mRNA COVID-19 vaccines and ADEM or TM. These findings translate to an extremely small absolute risk of ADEM (0.78 per million doses) and TM (1.82 per million doses) following vaccination; any potential risk of ADEM or TM should be weighed against the well-established protective benefits of vaccination against COVID-19 disease and its complications. This study demonstrates the value of the GVDN collaboration leveraging large population sizes to examine important vaccine safety questions regarding rare outcomes, as well as the value of linked population level datasets, such as VSHL, to rapidly explore associations that are identified.