Overall decrease in SARS-CoV-2 viral load and reduction in clinical burden: the experience of a hospital in northern Italy. (January 2021)

• Record Type: Journal Article
• Authors: Piubelli, Chiara; Deiana, Michela; Pomari, Elena; Silva, Ronaldo; Bisoffi, Zeno; Formenti, Fabio; Perandin, Francesca; Gobbi, Federico; Buonfrate, Dora
• Is Part Of: Clinical microbiology and infection. Volume 27:Number 1(2021)
• Page Start: 131.e1
• Page End: 131.e3
• Publication Date: 2021-01
• Subjects: Coronavirus -- Coronavirus disease 2019 -- COVID-19 -- SARS-CoV-2 -- Viral load; Medical microbiology -- Periodicals; Diagnostic microbiology -- Periodicals; Communicable diseases -- Periodicals; Infection -- Periodicals; 616.01
• DOI: 10.1016/j.cmi.2020.10.006
• Languages: English
• ISSNs: 1198-743X

Abstract

Abstract: Objectives: In Italy the burden of patients with coronavirus disease 2019 (COVID-19) gradually decreased from March to the end of May. In this work we aimed to evaluate a possible association between the severity of clinical manifestations and viral load over time during the epidemiological transition from high-to low-transmission settings. Methods: We reviewed the cases of COVID-19 diagnosed at the emergency room of our hospital, retrieving the proportion of patients admitted to the intensive care unit. A raw estimation of the viral load was done evaluating the Ct (cycle threshold) trend obtained from our diagnostic reverse transcriptase real-time PCR test. Results: The proportion of patients requiring intensive care significantly decreased from 6.7% (19/281) in March to 1.1% (1/86) in April, and to none in May (Fisher's test p 0.0067). As for viral load, we observed a trend of Ct increasing from a median value of 24 (IQR 19–29) to 34 (IQR 29–37) between March and May, with a statistically significant difference between March and April (pairwise Wilcoxon test with stepdown Bonferroni adjustment for multiple testing, p 0.0003). Conclusions: We observed a reduction over time in the proportion of patients with COVID-19 requiring intensive care, along with decreasing median values of viral load. As the epidemiological context changes from high-to low-transmission settings, people are presumably exposed to a lower viral load which has been previously associated with less severe clinical manifestations.