ABSTRACT
Introduction: During the first pandemic wave, Tuscany reported the fifth Italian highest number of COVID-19 cases in Italy even if this prevalence was lower if compared to other high-prevalence regions in the North of Italy. From September 2020, Tuscany situation has deeply changed with a significant increase of SARS CoV-2 positive cases, currently standing almost 234,000. Objectives: The Pediatric Tuscany Network continued the COVASAKI survey with the aim to track children who received a Kawasaki Syndrome (KS) or Multisystem Infalmmatory syndrome (MIS-C) diagnosis during the second vawe of COVID-19 pandemic. Methods: We retrospectively collected demographics, clinical findings, treatment and outcome of KS and MIS-C children between November 1st, 2020 to April 30th,2021 and compared the number of KS cases during this period to the number of reported KS children in the first pandemic vawe and in the previous five years in the same region. Results: 14 MIS-C children were admitted to 5 Paediatric Units (incidence 2.3/month), 10 boys and 4 girls (mean age of 9.6 years [IQR] 8.8-12). 11/14 patients required intensive care unit admission: 10 needed amines and 3 underwent mechanical ventilation. Echocardiography revealed a reduced left ventricular ejection fraction in 8/14. A diffuse coronary artery ectasia was found in 1. All children completely recovered with a timely immunomodulatory treatment with intravenous immunoglobulins, steroids and, in case of severe cardiac involvement, anakinra. Nasopharyngeal swabs and serological test for SARS CoV-2 resulted positive in 5/13 and 14/14 respectively. The MIS-C incidence rate, adjusted for the 5,170 children hospitalized, resulted 0.27% and represented the 13.9 % of paediatric COVID 19- related hospital admissions in Tuscany. Conversely, the number of observed KS significantly reduced comparing to the first six months of COVASAKI survey: 3 cases, 0.5 incidence/month vs 11 cases, 1.8 incidence/ month (p <0.03, RR 0.27, 95% CI 0.06 to 0.92). Comparing the 2.7 incidence/month of the 165 diagnosed KS from 1st January 2015 to 31th January 2020, a statistically significant difference has been detected (p <0.0005, RR 0.24, 95% CI 0.07 to 0.59). The same result has been found limiting the analysis to the 92 children with KS diagnosed during the same corresponding 6 months of the last 5 years: 3.0 versus 0.7 incidence/month (p <0.0002, RR 0.21, 95% CI 0.06 to 0.53). Conclusion: Our results seem in accordance with the hypothesis of an infectious trigger in KS pathogenesis. The stay-home imposed by pandemic and the extensive adoption of barrier protection devices have concomitantly reduced the incidence of respiratory infections among general and paediatric population. At this regard, the massive drop in the number of influenza and Syncytial Virus infections during the winter months results emblematic. From this point of view, it could be hypothesized that, in contrast to what had been previously reported in the early stages of its outbreak, the SARS CoV-2 pandemic could lead to a reduction rather than a substantial increase in the number of KS cases. Although indirectly, the behavioural measures adopted to contain the contagion or maybe further mechanisms not yet identified might be the reason.