Active safety surveillance of COVID-19 mRNA vaccines in children aged 5-15 years in Australia (preprint)

AusVaxSafety (the Australian active safety surveillance system) used SMS/email delivered surveys to actively solicit the short-term (within first 3 days after vaccination) adverse event profile of mRNA COVID-19 vaccines in children (aged 5-15 years) by age, dose, brand and pre-existing comorbidity. 392,268 survey responses for children aged 5-15 who received a COVID-19 vaccine between July 2021 and May 2022 (211,994 following BNT162b2 10mcg in children aged 5-11 years, 173,329 following BNT162b2 30mcg and 6,945 following mRNA-1273 100mcg in adolescents aged 12-15 years) were analysed. Adverse event rates were higher following dose 2 and 3 compared to dose 1 after all vaccines and highest following dose 2 of mRNA-1273 in 12-15 years. Fever was low in the youngest children (5 years old, any dose; 1,090/26,181 (4%)). Medical review rates remained low (0.3% overall) and impact on daily activities was also low (7% overall). No self-reported cases of myocarditis or pericarditis were identified. Ongoing active safety surveillance of lower dose mRNA vaccines in children under 5 years old is required to better understand safety as the vaccines roll out into this population age-group.

COVID-19 in children in NSW, Australia, during the 2021 Delta outbreak: Severity and Disease spectrum (preprint)

Objective(s): To describe the severity and clinical spectrum of SARS-CoV-2 infection in Australian children during the 2021 Delta outbreak. Design, Setting & Participants: A prospective cohort study of children <16 years with a positive SARS-CoV-2 nucleic acid test cared for by the Sydney Children's Hospital Network (SCHN) virtual and inpatient medical teams between 1 June-31 October 2021. Main outcome measures: Demographic and clinical data from all admitted patients and a random sample of outpatients managed under the SCHN virtual care team were analysed to identify risk factors for admission to hospital. Results: There were 17,474 SARS-CoV-2 infections in children <16 years in NSW during the study period, of whom 11,985 (68.6%) received care coordinated by SCHN. Twenty one percent of children infected with SARS-CoV-2 were asymptomatic. For every 100 SARS-CoV-2 infections in children <16 years, 1.26 (95% CI 1.06 to 1.46) required hospital admission for medical care; while 2.46 (95% CI 2.18 to 2.73) required admission for social reasons only. Risk factors for hospitalisation for medical care included age <6 months, a history of prematurity, age 12 to <16 years, and a history of medical comorbidities (aOR 7.23 [95% CI 2.92 to 19.4]). Of 17,474 infections, 15 children (median age 12.8years) required ICU admission; and 294 children required hospital admission due to social or welfare reasons. Conclusion: The majority of children with SARS-CoV-2 infection (Delta variant) had asymptomatic or mild disease. Hospitalisation was uncommon and occurred most frequently in young infants and adolescents with comorbidities. More children were hospitalised for social reasons than for medical care.