Analysis of the Factors That Affect the Detection Duration of SARS-CoV-2 in Loop Mediated Isothermal Amplification among COVID-19 Inpatients.

In COVID-19 patients who are immunocompromised or have severe COVID-19, the duration of infectious viral shedding may be longer, and a longer isolation duration is recommended. At the National Sagamihara Hospital, a decline in the viral load to end the isolation of hospitalized patients with COVID-19 was confirmed using loop-mediated isothermal amplification (LAMP). However, a subset of patients displayed LAMP positivity for more than 20 days after symptom onset. Therefore, we conducted a retrospective observational study to investigate the factors that affect the persistence of LAMP positivity. This study included a total of 102 participants. The severity of COVID-19 was mild (25.5%), moderate (67.6%), or severe (6.9%). The median number (interquartile range) of days until negative LAMP results from symptom onset were 16 (14-19) days. Multivariate logistic regression analysis showed that patients ≥55 years and/or those with the delta variant were correlated with persistent LAMP positivity for more than 20 days after symptom onset. This study identified age, the delta variant, and oxygen requirement as factors that contribute to persistently positive LAMP results. Therefore, it is posited that in these patients, the implementation of LAMP for deisolation would result in a prolonged isolation duration.