Multisystem inflammatory syndrome in adults: Comparison with other inflammatory conditions during the Covid-19 pandemic

COVID-19 vaccine effectiveness against severe omicron-related outcomes in children aged 5 to 11 years in Ontario: A Canadian immunization research network (CIRN) study

BACKGROUND

Understanding how the efficacy of COVID-19 vaccines translates from clinical trials to real-world settings is critical to inform evolving vaccination policies. The objective of this study was to assess COVID-19 vaccine effectiveness (VE) against severe COVID-19-related outcomes in children aged 5-11 years, including COVID-19-related hospital admissions and multisystem inflammatory syndrome in children (MIS-C).

METHODS

We conducted a retrospective, population-based cohort study using linked health administrative data in the first year following the emergence of the Omicron variant (January 2 to December 31, 2022) in Ontario, Canada. Baseline differences between subgroups of interest were compared using standardized differences. We used multivariable Cox proportional hazard regression models to estimate VE by time since last vaccine dose by treating vaccination as a time-varying exposure, compared to unvaccinated children.

RESULTS

We included a total of 1,058,740 children, of which 583,867 (55.1 %) had received at least one vaccine dose by the end of the study period. In total, there were 185 COVID-19-related hospital admissions and 39 cases of MIS-C. The rate of COVID-19-related admission was substantially higher in children with an underlying comorbid condition compared to children who were previously healthy (adjusted hazard ratio [aHR] = 4.77, 95 %CI, 3.56-6.38). VE against COVID-19-related admission ranged from 93 % (95 %CI, 52-99 %) 7-29 days after a second dose to 63 % (95 %CI; 41-77 %) ≥120 days after a second dose. There was no statistically significant difference in the rate of MIS-C in children who received at least one dose of the vaccine compared to unvaccinated children (aHR = 0.71; 95 %CI, 0.38-1.34).

CONCLUSIONS

We found that, for children aged 5-11 years, VE against COVID-19-related hospitalization was high in the first four months after a second dose. Children with comorbid conditions were found to be at much higher risk of COVID-19-related severe outcomes and thus may benefit most from COVID-19 vaccination.

Multisystem inflammatory syndrome in 1.2 million children: longitudinal cohort study of risk factors

BACKGROUND

We identified patient characteristics associated with an increased risk of developing MIS-C.

METHODS

We conducted a longitudinal cohort study of 1,195,327 patients aged 0-19 years between 2006 and 2021, including the first two waves of the pandemic (February 25-August 22, 2020 and August 23, 2020-March 31, 2021). Exposures included prepandemic morbidity, birth outcomes, and family history of maternal disorders. Outcomes included MIS-C, Kawasaki disease, and other Covid-19 complications during the pandemic. We calculated risk ratios (RRs) and 95% confidence intervals (CIs) for the association between patient exposures and these outcomes using log-binomial regression models adjusted for potential confounders.

RESULTS

Among 1,195,327 children, 84 developed MIS-C, 107 Kawasaki disease, and 330 other Covid-19 complications during the first year of the pandemic. Prepandemic hospitalizations for metabolic disorders (RR 11.3, 95% CI 5.61-22.6), atopic conditions (RR 3.34, 95% CI 1.60-6.97), and cancer (RR 8.11, 95% CI 1.13-58.3) were strongly associated with the risk of MIS-C, compared with no exposure. These same exposures were also associated with Kawasaki disease and other Covid-19 complications. However, birth characteristics and history of maternal morbidity were not associated with MIS-C development.

CONCLUSIONS

Children with pre-existing morbidity have a considerably elevated risk of MIS-C.

IMPACT

Morbidities that predispose children to multisystem inflammatory syndrome (MIS-C) are unclear. In this study, prepandemic hospitalizations for metabolic disorders, atopic conditions, and cancer were associated with an elevated risk of MIS-C. Birth characteristics and family history of maternal morbidity were not, however, associated with MIS-C. Pediatric morbidities may play a greater role in MIS-C onset than maternal or perinatal characteristics, and may help clinicians better recognize children at risk for this complication.

Biventricular Takotsubo Cardiomyopathy as an Unusual Presentation of SARS-CoV-2 mRNA Vaccine-Associated Multisystemic Inflammatory Syndrome

Biventricular takotsubo cardiomyopathy (BiTCM) is a rare entity, seldom reported. We describe a case of a female presenting with multisystemic inflammatory syndrome associated with the administration of a vaccine against coronavirus disease 2019 (COVID-19). In this particular case, the patient experienced the onset of symptoms shortly after receiving a COVID-19 vaccine. Early recognition of biventricular takotsubo cardiomyopathy and timely initiation of appropriate treatment are crucial. Prompt management includes stabilizing the patient's hemodynamic status, alleviating symptoms, and addressing any underlying causes, such as inflammation or immune-related responses. Close clinical surveillance is necessary to monitor the patient's cardiac function, assess response to treatment, and prevent potential complications.