Table 1 ICD-10 Codes considered as “upper respiratory tract infections” for the purpose of this study

We considered an upper respiratory tract infection diagnosis as any diagnosis registered according to the ICD-10 classification, as any the following:

ᅟ• JOO Acute nasopharyngitis [common cold]

ᅟ• JO1 Acute sinusitis (includes J01.0, J01.1, J01.2, J01.3, J01.4, J01.8, J01.9)

ᅟ• JO2 Acute pharyngitis (includes J02.0, J02.8, J02.9)

ᅟ• JO3 Acute tonsillitis (includes J03.0, J03.8, J03.9)

ᅟ• JO4 Acute laryngitis and tracheitis (includes J04.0, J04.1, J04.2)

ᅟ• JO5 Acute obstructive laryngitis [croup] and epiglottitis

ᅟ• JO6 Acute upper respiratory infections of multiple and unspecified sites (includes J06.0, J06.8, J06.9)

ᅟ• J10 Influenza due to other identified influenza virus (includes J10.1)

ᅟ• J11 Influenza due to unidentified influenza virus (includes J11.1)

We will consider as part of the upper respiratory tract infections, diseases of the middle ear categorized according to ICD-10 as:

ᅟ• H65 Nonsuppurative otitis media

ᅟ• H66 Suppurative and nonspecified otitis media