Received: 14 May 2022
Accepted: 21 June 2022
First Online: 6 July 2022
: This study was approved by the Sechenov University Local Ethics Committee on April 22, 2020 (protocol number 08–20, protocol amendment enabling serial follow-up of the cohort was approved on November 13, 2020), and Moscow City Independent Ethics Committee (abbreviate 1, protocol number 74). Parental consent was sought during hospital admission, and consent for the follow-up interview was sought via verbal confirmation during telephone interview. The consent process was approved by the ethics.
: Not applicable.
: JTS is supported by Welcome. CLHB declares a grant from The Netherlands Organisation for Health Research and Development. CA declares grant by Federal Ministry of Education and Research (BMBF) for EgePan Unimed project involving research activities on post-COVID-19 condition received by his institution. JG declares grants from the German Federal Ministry of Education and Research, German Federal Ministry of Health, and Danone Nutricia Research reception by his institution. He also reports Danone Nutricia Research patents in the area of breast milk composition pending. He acknowledges receiving an honorarium for serving as an Associate Editor for the Journal Pediatric Allergy and Immunology. MGS reports grants from the National Institute of Health Research UK, Medical Research Council UK, and Health Protection Research Unit in Emerging & Zoonotic Infections, University of Liverpool. He is also an independent external and non-remunerated member of Pfizer’s External Data Monitoring Committee for their mRNA vaccine program(s), a Chair of Infectious Disease Scientific Advisory Board of Integrum Scientific LLC, Greensboro, NC, USA, director of MedEx Solutions Ltd. He also declares being a minority owner at Integrum Scientific LLC, Greensboro, NC, USA, and majority owner at MedEx Solutions Ltd. He reports that a gift from Chiesi Farmaceutici S.p.A. was received by his Institution of Clinical Trial Investigational Medicinal Product without encumbrance and distribution of same to trial sites. He also serves as a non-remunerated independent member of HMG UK Scientific Advisory Group for Emergencies (SAGE), COVID-19 Response, and HMG UK New Emerging Respiratory Virus Threats Advisory Group (NERVTAG). LS declares project funding from the Welcome Trust. DB has participated to a peer-to-peer (PAACE) educational program on long COVID, sponsored by Pfizer. JOW reports funding from Danone/Nutricia, Friesland-Campina, and Airsonett. He also serves an Anaphylaxis Campaign clinical and scientific panel chairman and acknowledges travel expenses as a speaker covered by the World Allergy Organisation. DM reports receipt of grants from the British Embassy in Moscow, UK National Institute for Health Research (NIHR) and Russian Foundation for Basic Research. He also Co-Chair of International Severe Acute Respiratory and Emerging Infection Consortium (ISARIC) Global Paediatric Long COVID Working Group, member of ISARIC working group on long-term follow-up in adults, and co-lead of the PC-COS project. Other authors declare that they have no competing interests.