Long term follow up and outcomes of Covid-19 vaccine associated myocarditis in Victoria, Australia: A clinical surveillance study.

BACKGROUND: Myocarditis and myopericarditis are well described adverse events of special interest (AESI) following COVID-19 vaccinations. Although reports are reassuring regarding initial clinical outcomes, information about longer term outcomes remains limited. We aimed to further this knowledge and report outcomes to 6 months post diagnosis from a single population cohort. METHODS: Reports of myocarditis following COVID-19 vaccination were followed up by SAEFVIC (Surveillance of Adverse Events Following Vaccination in the Community), the state-wide vaccine safety service for Victoria, Australia. Confirmed myocarditis cases (Brighton Collaboration Criteria levels 1-3) were followed up via surveys at 1, 3 and 6 months post symptom onset. Responses received between 22 February 2021 and 30 September 2022 were analysed. RESULTS: 87.5 % (N = 182) of eligible participants completed at least 1 survey report. 377 reports were analysed. 76.9 % of completed reports were from male patients. The median age of patients was 21 years [IQR: 16 to 32]. 54.8 % (n = 74) of survey reports at 6 months, reported ongoing symptoms. At all follow-up time points, females were significantly more likely to have ongoing symptoms. At 6 months, 51.9 % of male respondents reported symptom resolution compared to 22.6 % of female patients (p = 0.002). Females were also more likely to continue medication and have ongoing exercise restrictions. However, males were significantly more likely to have higher initial peak troponin results and abnormal initial cardiac imaging investigations. CONCLUSIONS: There appears to be a significant proportion of patients who experience ongoing symptoms to 6 months post onset amongst patients that experience these AESI. Male patients were more likely to report earlier and more complete symptom recovery, despite significantly higher average initial peak troponin. This difference in phenotypic presentation in females compared to males warrants further investigation and there is a need for longer term follow up data.

Myocarditis and myopericarditis cases following COVID-19 mRNA vaccines administered to 12-17-year olds in Victoria, Australia.

IMPORTANCE: COVID-19 mRNA vaccine-associated myocarditis has previously been described; however specific features in the adolescent population are currently not well understood. OBJECTIVE: To describe myocarditis adverse events following immunisation reported following any COVID-19 mRNA vaccines in the adolescent population in Victoria, Australia. DESIGN: Statewide, population-based study. SETTING: Surveillance of Adverse Events Following Vaccination in the Community (SAEFVIC) is the vaccine-safety service for Victoria, Australia. PARTICIPANTS: All SAEFVIC reports of myocarditis and myopericarditis in 12-17-year-old COVID-19 mRNA vaccinees submitted between 22 February 2021 and 22 February 2022, as well as accompanying diagnostic investigation results where available, were assessed using Brighton Collaboration criteria for diagnostic certainty. EXPOSURES: Any mRNA COVID-19 vaccine. MAIN OUTCOMES/MMEASURE: Confirmed myocarditis as per Brighton Collaboration criteria (levels 1-3). RESULTS: Clinical review demonstrated definitive (Brighton level 1) or probable (level 2) diagnoses in 75 cases. Confirmed myocarditis reporting rates were 8.3 per 100 000 doses in this age group. Cases were predominantly male (n=62, 82.7%) and post dose 2 (n=61, 81.3%). Rates peaked in the 16-17-year-old age group and were higher in males than females (17.7 vs 3.9 per 100 000, p=<0.001).The most common presenting symptoms were chest pain, dyspnoea and palpitations. A large majority of cases who had a cardiac MRI had abnormalities (n=33, 91.7%). Females were more likely to have ongoing clinical symptoms at 1-month follow-up (p=0.02). CONCLUSION: Accurate evaluation and confirmation of episodes of COVID-19 mRNA vaccine-associated myocarditis enabled understanding of clinical phenotypes in the adolescent age group. Any potential vaccination and safety surveillance policies needs to consider age and gender differences.

What is the easier and more reliable dose calculation for iv phenytoin in children at risk of developing convulsive status epilepticus, 18 mg/kg or 20 mg/kg?

BACKGROUND: With the Convulsive Status Guidelines due for renewal, we wondered if a phenytoin dose of '20 mg/kg' would be easier to calculate correctly and therefore safer than the current '18 mg/kg'. An educational exercise in dose calculation was therefore undertaken to assess ease of calculation. METHOD: A standard question paper was prepared, comprising five clinical scenarios with children of varying ages and estimated body weights. Medical students, trainee doctors at registrar and senior house officer level, and consultant paediatricians were asked to complete the exercise, in private, by one of two medical students (SD, PS). Calculations were done with and without a calculator, for 18 mg/kg and for 20 mg/kg in randomised order. Speed and errors (greater than 10%) were determined. The data analysis was performed using SPSS version 18. RESULTS: All answered all 20 scenarios, giving a total of 300 answers per doctor/student group, and 300 answers per type of calculation. When comparing the 2 doses, the numbers of errors more than 10% were significantly less in 20 mg/kg dose (0.33%) as compared to the 18 mg/kg dose (9.3%) (p<0.0001). Speed off calculation was significantly decreased in 20 mg/kg dose when compared with 18 mg/kg dose, with (p<0.001) or without (p<0.0001) the calculator. Speed was more than halved and errors were much less frequent by using a calculator, for the 18 mg/kg dose but no difference with or without the calculator for 20 mg/kg dose. CONCLUSION: We recommend that the future guidelines should suggest iv Phenytoin at 20 mg/kg rather than 18 mg/kg. This will make the calculation easier and reduce the risk of significant errors.