Incidence and Clinical Phenotype of Multisystem Inflammatory Syndrome in Children After Two SARS-CoV-2 Pandemic Waves: A Croatian Prospective Nationwide Study.

This prospective nationwide study in Croatia (March 1, 2020-December 31, 2021) embraced 121 children with multisystem inflammatory syndrome. Incidence rates, disease course and outcomes were similar to those reported from other European countries. The severe acute respiratory syndrome coronavirus 2 virus Alpha strain appeared associated with a higher propensity to result in multisystem inflammatory syndrome in children than the Delta strain but did not appear related to disease severity.

Comparison of children with kawasaki disease and MIS-C

The goal of this research was to compare clinical signs, symptoms and laboratory findings in children diagnosed with Kawasaki disease and those with multisystem inflammatory syndrome in children (MIS-C) associated with coronavirus disease 2019 (COVID-19).We reviewed medical records of children diagnosed with Kawasaki disease or MIS-C hospitalised in the University Hospital for Infectious Diseases ‘’Dr. Fran Mihaljević’’ in the period from February 25th 2020 to February 24th 2021. We defined MIS-C using World Health Organisation criteria.There were 13 children diagnosed with Kawasaki disease and 23 children diagnosed with MIS-C hospitalised in this period. The average duration of hospitalisation was similar in both groups, approximately 8 days. Boys were overall more affected (66%) than girls. Children with MIS-C were older and more often gastrointestinal symptoms were present. When comparing laboratory results, children in the MIS-C group had higher C-reactive protein levels and lower platelet count. Also, they required intensive care treatment more frequently. The first therapy of choice for all children with Kawasaki disease was monotherapy with intravenous immunoglobulins (IVIG). Monotherapy with IVIG was used in 15 patients with MIS-C, while 8 of them were initially treated with the combination of IVIG and corticosteroids. One death case occured in the MIS-C group, and none in the Kawasaki group.Multisystem inflammatory syndrome in children associated with COVID-19 is a new pediatric disease that is dangerous and potentially lethal. Although many clinical and laboratory findings overlap with Kawasaki disease, this disease requires intensive care treatment more often. It can also have a fatal outcome – therefore prompt recognition and early treatment are crucial.

Epidemiological and clinical features of Croatian children and adolescents with a PCR-confirmed coronavirus disease 2019: differences between the first and second epidemic wave.

AIM: To describe epidemiological and clinical features of Croatian children and adolescents with a polymerase chain reaction (PCR)-confirmed coronavirus disease 2019. METHODS: Data on patients aged ≤19 years with a positive SARS-CoV-2 PCR test recorded in the period March 12-May 12 (first wave) and June 19-July 19, 2020 (second wave) were retrospectively analyzed. The periods were separated by several weeks with no incident cases. RESULTS: We analyzed data on 289 children and adolescents (6.5% of all cases; incidence rate [IR]=3.54, 95% confidence interval [CI] 3.14-3.97/million person-days), 124 in the first wave (IR=2.27) and 165 in the second wave (IR=6.37): IRR second/first=2.71 (2.13-3.44). During the first wave, the incidence was highest in infants (IR=3.48), while during the second wave it progressively increased to IR = 7.37 in 15-19-year olds. Family members were the key epidemiological contacts (72.6% cases), particularly during the first wave (95.8% vs 56.3%). Overall, 41.3% patients were asymptomatic, 25.3% in the first and 52.6% in the second wave. Age 15-19 years (vs younger) was associated with a higher (RR = 1.26, 1.02-1.54) and infection in the second wave with a lower probability (RR=0.66, 0.53-0.81) of being symptomatic. The most common symptoms were fever, cough, and rhinorrhea. In children aged ≥7 years, headache, anosmia/ageusia, and sore throat were also recorded. Only one child suffered a severe disease. All but 18 (7.8%) children were treated only symptomatically, and all fully recovered. CONCLUSION: A large proportion of SARS-CoV-2 PCR-positive children/adolescents were asymptomatic. The associated disease was predominantly mild, comparably so in the first and second pandemic wave.