Backgrounds:

Australia has utilized two mRNA vaccines as part of its COVID-19 vaccine strategy in 12-17 year-olds, namely Comirnaty BNT162b2 COVID-19 (Pfizer-BioNTech) and Spikevax mRNA-1273 (Moderna).

Of particular interest in the young adult population is post-vaccination myocarditis causally associated with COVID-19 mRNA vaccines. Post-licensure observational and report-based case studies confirmed the highest risk group is young males (<24 years old) following the 2^nd vaccine dose.

Due to this AESI signal, the risk, clinical manifestations and follow-up of myocarditis has been of particular interest. This study describes clinical presentation and evaluation of myocarditis AESI following mRNA COVID-19 vaccination in 12–17-year-old adolescents in Victoria, Australia.

Methods

Identified reports of myocarditis in 12–17-year-old vaccinees submitted to SAEFVIC, the state-wide vaccine safety service, between 22 February and 30 November 2021 were assessed. Diagnostic test results were obtained to confirm the diagnoses. Each case was categorized by two independent experts utilizing the Brighton Collaboration definition with graded levels of certainty.

Results:

Rigorous clinical review demonstrated definite (Brighton level 1) or probable (level 2) diagnoses in 53 cases, with one case possible (level 3). As of 30th November 2021, the 54 reports of confirmed myocarditis, equated to a rate of 7.0 per 100,000 doses in this age group.

Cases were predominantly male (n=48, 88.9%) and post dose 2 (n=44, 81.5%). Rates peaked in the 16–17-year-old age group and were higher in males than females (12.2 v 1.6 per 100,000, p=<0.001).

Troponin levels differed between sexes, with males recording substantially higher levels.

Conclusions/Learning Points:

Accurate evaluation and confirmation of episodes of COVID-19 mRNA vaccine associated myocarditis enabled understanding of clinical phenotypes in the pediatric and adolescent age group. Any potential vaccination and safety surveillance policies needs to consider age and gender differences.

Backgrounds:

Febrile seizures are the most common cause of seizure in childhood.They occur in the presence of a fever (>38 degrees Celsius) in children aged between 6 months and 5 years. Viruses are well-described as the predominant causative agents and specific viruses have previously been implicated, including Human Herpesvirus-6 (HHV-6),Influenza A and B, Respiratory syncytial virus (RSV), Parainfluenza, Adenovirus, Rhinovirus and Enterovirus.

Recent innovations in viral respiratory molecular diagnostics allow multiple viruses to be tested simultaneously using multiplex polymerase chain reaction (PCR). SNOTWATCH is a de-identified ecologic analysis platform capturing population level molecular diagnostic results together with hospital and primary care encounters. This project aims to utilise PCR data to understand the relationship between respiratory virus circulation and febrile seizures at a population level. We have created a novel statistical model for assessing these relationships in both time and space.

Methods

Our ecological study assessed relationships between presentations of febrile seizures and nine respiratory viruses detected at the largest hospital network in Melbourne, Australia, from 2010-2019. Associations were studied temporally and spatiotemporally through mixed-effects Poisson regression analysis, using monthly incidence of febrile seizures and positive PCR tests.

Results:

Febrile seizure incidence peaked in June-September each year. Temporal analysis showed febrile seizures were significantly associated with Human metapneumovirus (1.19 RR), Influenza A (1.49 RR), Influenza B (1.33 RR) and RSV (1.52 RR) (Figure 1). Spatiotemporal analysis supported the association between febrile seizures and Influenza A, Influenza B and RSV (1.25, 1.12 and 1.20 RR respectively, p<0.0

Conclusions/Learning Points:

With over 90,000 PCR results and almost 5,000 febrile seizure presentations, our findings confirm the importance of understanding viral circulation patterns and their implications for paediatric health outcomes. Our statistical method may be used in predictive modelling to inform public health policy.

Backgrounds:

Myocarditis has been identified as an adverse event associated with COVID-19 mRNA vaccination, with some countries implementing age-related preferential recommendations using Comirnaty (Pfizer) over Spikevax (Moderna). Australia is one of few countries administering both mRNA vaccines in young adolescents aged 12-17 year-olds, with 87% two-dose coverage of this population achieved by end of 2021.

Methods

Reports of myocarditis following immunisation submitted to Victoria’s vaccine safety surveillance system, SAEFVIC, from 22 February to 31 December 2021 were compared as counts and rates by age-group, dose and mRNA vaccine brand administered. Cases were confirmed using Brighton Collaboration criteria, with those meeting level 1 and level 2 clinical confidence included in analyses. Rates per 100,000 doses administered were estimated according to the Australian Immunisation Registry (AIR), and 90% Poisson confidence intervals calculated.

Results:

185 reports of myocarditis (162 following Comirnaty, 23 post Spikevax) were reported following almost 7 million doses of mRNA vaccines administered (6,572,861 Comirnaty, 376,151 Spikevax), a rate of 2.7 per 100,000 doses. The myocarditis reporting rate following Spikevax was more than double that of Comirnaty (6.1 vs 2.5 per 100,000, p<0.001) and for each dose (Table 1). For both vaccines, the highest reporting rates were observed for 16-17 year-old males following dose 2 (29.0 per 100,000 mRNA second doses), with a reduction in the incidence of cases for the 12-15 and 18-24 age groups.

Conclusions/Learning Points:

Even in adolescents, the risk-benefit equation remains in favour of vaccination, especially given the risk of myocarditis following COVID-19 disease. Australia has the luxury of two available efficacious and safe mRNA vaccines. Mitigating the risk of this rare adverse event via preferential age recommendations in the highest risk adolescent age-group is an option. 

Backgrounds:

Australia has utilized two mRNA vaccines as part of its COVID-19 vaccine strategy in 12-17 year-olds, namely Comirnaty BNT162b2 COVID-19 (Pfizer-BioNTech) and Spikevax mRNA-1273 (Moderna).

Of particular interest in the young adult population is post-vaccination myocarditis causally associated with COVID-19 mRNA vaccines. Post-licensure observational and report-based case studies confirmed the highest risk group is young males (<24 years old) following the 2^nd vaccine dose.

Due to this AESI signal, the risk, clinical manifestations and follow-up of myocarditis has been of particular interest. This study describes clinical presentation and evaluation of myocarditis AESI following mRNA COVID-19 vaccination in 12–17-year-old adolescents in Victoria, Australia.

Methods

Identified reports of myocarditis in 12–17-year-old vaccinees submitted to SAEFVIC, the state-wide vaccine safety service, between 22 February and 30 November 2021 were assessed. Diagnostic test results were obtained to confirm the diagnoses. Each case was categorized by two independent experts utilizing the Brighton Collaboration definition with graded levels of certainty.

Results:

Rigorous clinical review demonstrated definite (Brighton level 1) or probable (level 2) diagnoses in 53 cases, with one case possible (level 3). As of 30th November 2021, the 54 reports of confirmed myocarditis, equated to a rate of 7.0 per 100,000 doses in this age group.

Cases were predominantly male (n=48, 88.9%) and post dose 2 (n=44, 81.5%). Rates peaked in the 16–17-year-old age group and were higher in males than females (12.2 v 1.6 per 100,000, p=<0.001).

Troponin levels differed between sexes, with males recording substantially higher levels.

Conclusions/Learning Points:

Accurate evaluation and confirmation of episodes of COVID-19 mRNA vaccine associated myocarditis enabled understanding of clinical phenotypes in the pediatric and adolescent age group. Any potential vaccination and safety surveillance policies needs to consider age and gender differences.

Backgrounds:

Myocarditis has been identified as an adverse event associated with COVID-19 mRNA vaccination, with some countries implementing age-related preferential recommendations using Comirnaty (Pfizer) over Spikevax (Moderna). Australia is one of few countries administering both mRNA vaccines in young adolescents aged 12-17 year-olds, with 87% two-dose coverage of this population achieved by end of 2021.

Methods

Reports of myocarditis following immunisation submitted to Victoria’s vaccine safety surveillance system, SAEFVIC, from 22 February to 31 December 2021 were compared as counts and rates by age-group, dose and mRNA vaccine brand administered. Cases were confirmed using Brighton Collaboration criteria, with those meeting level 1 and level 2 clinical confidence included in analyses. Rates per 100,000 doses administered were estimated according to the Australian Immunisation Registry (AIR), and 90% Poisson confidence intervals calculated.

Results:

185 reports of myocarditis (162 following Comirnaty, 23 post Spikevax) were reported following almost 7 million doses of mRNA vaccines administered (6,572,861 Comirnaty, 376,151 Spikevax), a rate of 2.7 per 100,000 doses. The myocarditis reporting rate following Spikevax was more than double that of Comirnaty (6.1 vs 2.5 per 100,000, p<0.001) and for each dose (Table 1). For both vaccines, the highest reporting rates were observed for 16-17 year-old males following dose 2 (29.0 per 100,000 mRNA second doses), with a reduction in the incidence of cases for the 12-15 and 18-24 age groups.

Conclusions/Learning Points:

Even in adolescents, the risk-benefit equation remains in favour of vaccination, especially given the risk of myocarditis following COVID-19 disease. Australia has the luxury of two available efficacious and safe mRNA vaccines. Mitigating the risk of this rare adverse event via preferential age recommendations in the highest risk adolescent age-group is an option.