Table 2.

Long COVID definition in children

	Duration of symptoms	Previous history	Other criteria
Research definition of long COVID in children and youths aligned to WHO definition [6]	At least 12 weeks after initial testing	Confirmed SARS-CoV-2 infection (PCR, lateral flow antigen test, or antibody test)	- One or more persisting physical symptom - Cannot be explained by an alternative diagnosis - Impact on everyday functioning - Symptoms may continue or develop after the infection - May fluctuate or relapse over time