A Potential Novel Treatment for Chronic Cough in Long COVID Patients: Clearance of Epipharyngeal Residual SARS-CoV-2 Spike RNA by Epipharyngeal Abrasive Therapy

A major target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the epipharyngeal mucosa. Epipharyngeal abrasive therapy (EAT) is a Japanese treatment for chronic epipharyngitis. EAT is a treatment for chronic epipharyngitis in Japan that involves applying zinc chloride as an anti-inflammatory agent to the epipharyngeal mucosa. Here, we present a case of a 21-year-old man with chronic coughing that persisted for four months after a diagnosis of mild coronavirus disease 2019 (COVID-19), who was treated by EAT. We diagnosed chronic epipharyngitis as the cause of the chronic cough after the SARS-CoV-2 infection. SARS-CoV-2 spike RNA had persisted in the epipharyngeal mucosa of this Long COVID patient. EAT was performed once a week for three months, which eliminated residual SARS-CoV-2 RNA and reduced epipharyngeal inflammation. Moreover, a reduction in the expression of proinflammatory cytokines was found by histopathological examination. We speculate that the virus was excreted with the drainage induced by EAT, which stopped the secretion of proinflammatory cytokines. This case study suggests that EAT is a useful treatment for chronic epipharyngitis involving long COVID.