COVID-19 and idiopathic nephrotic syndrome in children: systematic review of the literature and recommendations from a highly affected area

Background Coronavirus Disease 2019 has spread from China as a global pandemic, Italy being one of the earliest affected countries. The infection displays a more complicated and often fatal course in adults with a history of kidney disease, while it does not seem to affect children in the same way. Pediatric patients with idiopathic nephrotic syndrome (INS), with or without chronic immunosuppressive therapy, are at greater risk of infections which may also trigger relapses. Objectives We performed a systematic review of the literature to identify all articles on SARS-CoV-2 infections in children with INS in order to describe the severity of all SARS-CoV-2 infections reported in children with INS, to evaluate the risk of new onset and relapses associated with SARS-CoV-2 infection, and to draw recommendations on their management and vaccination. The search was conducted on the following databases: MEDLINE (via Pubmed), Google Scholar, and Web of Science. The search methodology used with the selected free text terms or MesH was (“nephrotic syndrome” OR “idiopathic nephrotic syndrome”) and (“covid 19” OR "severe acute respiratory syndrome coronavirus 2" OR "2019-nCoV" OR "SARS-CoV-2"). Results The literature search provided 36 records. After screening for their relevance to the topic, 11 studies were selected. Two additional publications were identified through the reference list of all included articles and 13 articles were included in the review. A total of 43 cases of children with INS and SARS-CoV-2 infection have been reported; the course of the disease was mild for most patients with low need of respiratory support and no death in high income countries. In 5 patients, the infection was complicated by relapse, which anyway showed a good response to steroids. Two children had a new onset of INS during a SARS-CoV-2 infection. Conclusions Children with INS, with or without immunosuppression, are not at higher risk of severe SARS-CoV-2 infection. Relapse is a possible complication, but steroid treatment is safe and effective. After summarizing the evidence, we have suggested recommendations for the management of children with INS during the pandemic and the vaccination campaign. Graphical abstract