Hyposmia and hypogeusia are not unique to children with acute SARS-CoV-2 infection in the omicron era, but long COVID can cause continuing taste and smell impairments that are not detected by validated questionnaires, according to a study.
“It is therefore essentially necessary to apply objective and subjective methods at the same time to improve the detection of hyposmia and hypogeusia in children,” said the investigators, who examined objective and subjective impairment in paediatric patients with acute SARS-CoV-2 infection (n=30) and other upper respiratory tract infection (n=34) from July 2021 to October 2022.
Children with (PI+; n=28) and without (PI−; n=13) remaining symptoms ≥12 weeks after SARS-CoV-2 infection and noninfected individuals (n=18; control) were also included in the analysis. Those with acute infections were examined blinded regarding the results of their polymerase chain reaction test.
Nearly a fifth of children had abnormal test results, with severe hyposmia seen in 17 percent of those with upper respiratory tract infection and 21 percent in the PI+ group. Severe hypogeusia was also detected in 18 percent of children with acute SARS-CoV-2 infection and in 12 percent and 10 percent of those in the PI+ and PI‒ groups, respectively. [Pediatr Infec Dis J 2026;45:510-515]
More children in the PI+ group experienced subjective smell impairment (32 percent vs ≤7 percent in all other groups) and taste impairment (PI+ vs those with acute SARS-CoV-2 infection and other groups: 29 percent vs 14 percent and ≤10 percent, respectively).
Furthermore, children in the postinfection groups experienced significantly more negative sensory affects (ie, “tastes or smells disgusting,” 14 percent each), with no association with abnormal test results.
“The greatest burden of children with long COVID and persisting symptoms is long-lasting changes (eg, disgust) in the taste perception of individual foods, which are underestimated by objective test methods,” the investigators said. “Therefore, it is crucial to differentiate between objectifiable and subjective disturbances.”
Aetiology
Although the nerve transmission differs, smell and taste disorders were usually considered as symptom complexes, according to the investigators. [Chem Senses 2023;48:bjad043; OTO Open 2020;4:2473974X20957975]
Approaches to understanding the pathophysiology of olfactory disorders caused by COVID-19 differ, but no consensus exists regarding the exact cause of hypogeusia. Possible aetiologies are as follows: tissue hypoxia, neurologic damage, and immune or inflammatory reactions. [Bosn J Basic Med Sci 2022;23:344-350; Am J Rhinol Allergy 2014;28:50-53]
“It is reasonable to speculate that infection with the virus causes damage to the second and third neurons of taste processing, and disrupts the connection with centres of emotional processing, such as the amygdala,” the investigators said. [EClinicalMedicine 2023;58:101883]
Previous studies have also noted considerable discrepancies between the prevalence of objectively and subjectively determined odor disorders. However, these subjective methods are often neither standardized nor validated, only a few studies have explored the altered taste phenomena. [Chem Senses 2020;45:865-874; Otolaryngol Head Neck Surg 2006;134:488-490; JMIR Form Res 2021;5:e29086]
“Based on our study design, we were able to rule out hypogeusia as the cause of aversive disorders,” the investigators said. “But regardless of underlying conditions, objective and subjective smell and taste disturbances can impact safety, mental health and food intake and are daily-life relevant problems for all those affected.” [Chem Senses 2021;46:1-10]