Effects of oral care on prolonged viral shedding in coronavirus disease 2019 (COVID‐19)

Warabi, Yoko; Tobisawa, Shinsuke; Kawazoe, Tomoya; Murayama, Aki; Norioka, Ryohei; Morishima, Ryo; Inoue, Tomoyuki; Shimizu, Toshio; Takahashi, Kazushi

AIM: To assess the effects of oral care on prolonged viral shedding in coronavirus disease 2019 (COVID‐19) patients. METHODS AND RESULTS: We evaluated the clinical course of eight COVID‐19 patients, including their duration of viral shedding, by PCR testing of nasopharyngeal swabs. The average time from the onset of symptoms until the virus was no longer detectable was 31.6 ± 11.8 days (mean ± SD; range 17‐53). Thus, it took 15.1 ± 14.7 (1‐40) days from the time of clinical recovery for the virus to become undetectable. In two patients who had mental retardation and psychiatric disorders, the viral shedding period continued for 44 days or 53 days. These two patients did not voluntarily brush their teeth. When they were instructed on the importance of oral care, including tooth brushing and gargling, their tests for the coronavirus became negative. CONCLUSION: Most of the patients with COVID‐19 had a viral shedding period of 30 days or less. In cases of prolonged viral shedding (≥44 days), noninfectious viral nucleic acid may have accumulated in uncleaned oral cavities and continued to be detected. We propose that tooth brushing and gargling remove such viral nucleic acid and improve the accuracy of PCR testing.