| News

Lower risk of multi-system inflammatory syndrome in Aussie kids with Omicron COVID-19 variant

New research from the Paediatric Active Enhanced Disease Surveillance (PAEDS) network shows rates of multi-system inflammatory syndrome in children (MIS-C) – also known as paediatric multisystem inflammatory syndrome (PIMS-TS) – were significantly lower during the Omicron COVID-19 variant period than during  pre-Delta and Delta COVID-19 variant periods.

PAEDS hospital network sentinel surveillance, which covers more than 80% of tertiary paediatric beds across Australia, identified 107 cases of MIS-C/PIMS-TS in children aged 0–19 years from 1 May 2020 to 30 April 2022. Cases were classified as occurring during three defined periods determined by the dominant COVID-19 variant circulating at the time of COVID-19 infection.

Of the 107 identified MIS-C/PIMS-TS cases, 5 (5%) occurred during the pre-Delta/ancestral strain period from March 2020 to May 2021, 30 (28%) during the Delta period from June 2021 to November 2021 and 72 (67%) during the Omicron period from December 2021 to April 2022.

The rate of MIS-C/PIMS-TS in Australian children reduced over time with the identification of each new dominant COVID-19 variant, with 13 cases per 10,000 notified COVID-19 infections during the pre-Delta period, reducing to 5 cases per 10,000 notified COVID-19 infections during the Delta period and decreasing further to 0.8 cases per 10,000 notified COVID-19 infections during the Omicron period.

These data are similar to literature published from the United Kingdom, Israel and Denmark, where significantly lower rates of MIS-C/PIMS-TS relative to COVID-19 infection were observed during the Omicron period, with the study findings supporting a contention that changes in viral antigens likely contributed to reduction in MIS-C/PIMS-TS incidence.

MIS-C/PIMS-TS is a rare condition that occurs predominantly in children following COVID-19 infection and can cause inflammation of the heart, lungs, kidneys, brain, skin and eyes. It can be serious and require hospitalisation, with 22% of identified cases in the study requiring ICU admission.

PAEDS is undertaking surveillance of MIS-C/PIMS-TS in Australia on an ongoing basis, with case data published on the PAEDS website monthly.

Read the full study here