COVID-19：嗅覚障害 軽症患者ほど嗅覚障害目立つ可能性？

18のヨーロッパの病院での 検討

嗅覚障害は軽症だと85.9％、中等度/重度では 4.6-6.9%程度

発症後60日めの主観的嗅覚回復しなかった症例は 24.1%

平均主観的有症状期間は 21.6±17.6日間

客観的嗅覚確認による低嗅覚/無嗅覚は 54.7% と 36.6%

60日後は各々 15.3%、4.7%

ベースラインで客観的嗅覚確認重症度ほど持続性嗅覚障害を生じやすい

Prevalence and 6‐month recovery of olfactory dysfunction: a multicentre study of 1363 COVID‐19 patients

JIM ,First published: 05 January 2021

https://doi.org/10.1111/joim.13209

https://onlinelibrary.wiley.com/doi/10.1111/joim.13209

The main hypothesis underlying the higher prevalence of anosmia in mild COVID‐19 would consist of differences in the immune response to the infection in mild and moderate‐to‐critical patients [21]. In this hypothesis, patients with mild COVID‐19 could have a better local immunological response through a higher production of IgA, which could limit the virus spread into the organism. The limited virus spread in the host body could therefore be associated with a mild clinical form of the disease. Due to the local inflammatory reaction and the well‐demonstrated olfactory cell expression of angiotensin‐converting enzyme‐2 (ACE2) and TMPRSS2 [22, 23], the patients with mild disease could have stronger impairment of olfactory cells. In addition, we observed that severe and critical patients had a significantly higher level of IgG than mild patients, which may corroborate some findings of the literature [24]. However, this hypothesis requires additional studies involving immunological sera, saliva and nasal secretion analyses. 

局所炎症反応とACE2とTMPRSS2の嗅覚細胞発現により、軽症疾患において嗅覚細胞の障害が生じやすくなる可能性・・・だそうです