Background Olfactory dysfunction associated with SARS-CoV-2 infection in
children has not been verified by a validated olfactory test. We aimed to
determine whether these complaints are objectifiable (test-based hyposmia), how
often they occur during acute SARS-CoV-2 infection compared to other upper
respiratory tract infections (URTI), as well as in children recovered from
COVID-19 compared to children with long COVID.
Methods Olfactory testing (U-sniff test; hyposmia<8 points) and
survey-based symptom assessments were performed in 434 children (5–17
years; 04/2021–06/2022). 186 symptom-free children
served as controls. Of the children with symptoms of acute respiratory tract
infection, SARS-CoV-2 PCR test results were positive in 45 and negative in 107
children (URTI group). Additionally, 96 children were recruited at least 4 weeks
(17.6±15.2 weeks) after COVID-19, of whom 66 had recovered and 30 had
developed long COVID.
Results Compared to controls (2.7%), hyposmia frequency was
increased in all other groups (11–17%, p<0.05), but no
between-group differences were observed. Only 3/41 children with
hyposmia reported complaints, whereas 13/16 children with complaints
were normosmic, with the largest proportion being in the long-COVID group
(23%, p<0.05).
Conclusion Questionnaires are unsuitable for assessing hyposmia frequency
in children. Olfactory complaints and hyposmia are not specific for SARS-CoV-2
infection. The number of complaints in the long-COVID group could result from
aversive olfactory perception, which is undetectable with the U-sniff test.