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

  • Chiara Piubelli
    Affiliations
    Department of Infectious and Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar di Valpolicella, 37024 Verona, Italy
    Search for articles by this author
  • Michela Deiana
    Affiliations
    Department of Infectious and Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar di Valpolicella, 37024 Verona, Italy
    Search for articles by this author
  • Elena Pomari
    Affiliations
    Department of Infectious and Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar di Valpolicella, 37024 Verona, Italy
    Search for articles by this author
  • Ronaldo Silva
    Affiliations
    Department of Infectious and Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar di Valpolicella, 37024 Verona, Italy
    Search for articles by this author
  • Zeno Bisoffi
    Affiliations
    Department of Infectious and Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar di Valpolicella, 37024 Verona, Italy

    Department of Diagnostics and Public Health, University of Verona, 37134 Verona, Italy
    Search for articles by this author
  • Fabio Formenti
    Affiliations
    Department of Infectious and Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar di Valpolicella, 37024 Verona, Italy
    Search for articles by this author
  • Francesca Perandin
    Affiliations
    Department of Infectious and Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar di Valpolicella, 37024 Verona, Italy
    Search for articles by this author
  • Federico Gobbi
    Affiliations
    Department of Infectious and Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar di Valpolicella, 37024 Verona, Italy
    Search for articles by this author
  • Dora Buonfrate
    Correspondence
    Corresponding author: Dora Buonfrate, IRCCS Sacro Cuore Don Calabria hospital, Via Sempreboni 5, 37024 Negrar, Verona, Italy.
    Affiliations
    Department of Infectious and Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar di Valpolicella, 37024 Verona, Italy
    Search for articles by this author
Open AccessPublished:October 11, 2020DOI:https://doi.org/10.1016/j.cmi.2020.10.006

      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.

      Keywords

      References

        • Romagnani P.
        • Gnone G.
        • Guzzi F.
        • Negrini S.
        • Guastalla A.
        • Annunziato F.
        • et al.
        The covid-19 infection: lessons from the Italian experience.
        J Public Health Policy. 2020; : 1-7
        • Dong E.
        • Du H.
        • Gardner L.
        An interactive web-based dashboard to track covid-19 in real time.
        Lancet Infect Dis. 2020; 20: 533-534
      1. Covid-19 dashboard by the center for systems science and engineering (csse) at Johns Hopkins University (JHU).
        • Italian Prime Ministry
        Decreto del presidente del consiglio dei ministri.
        • World Health Organization
        Laboratory testing for coronavirus disease (covid-19) in suspected human cases, interim guidance.
        2020
        • Corman V.M.
        • Landt O.
        • Kaiser M.
        • Molenkamp R.
        • Meijer A.
        • Chu D.
        • et al.
        Detection of 2019 novel coronavirus (2019-ncov) by real-time rt-pcr.
        Euro Surveill. 2020; 252000045https://doi.org/10.2807/1560-7917.ES.2020.25.3.2000045
        • Livak K.J.
        • Schmittgen T.D.
        Analysis of relative gene expression data using real-time quantitative pcr and the 2(-delta delta c(t)) method.
        Methods (San Diego, Calif). 2001; 25: 402-408
        • Chen D.
        • Hu C.
        • Su F.
        • Song Q.
        • Wang Z.
        Exposure to SARS-CoV-2 in a high transmission setting increases the risk of severe covid-19 compared to exposure to a low transmission setting?.
        J Trav Med. 2020; 27taaa094
        • Liu Y.
        • Yan L.M.
        • Wan L.
        • Xiang T.-X.
        • Le A.
        • Liu J.-M.
        • et al.
        Viral dynamics in mild and severe cases of covid-19.
        Lancet Infect Dis. 2020; 20: 656-657
        • Poletti P.
        • Tirani M.
        • Cereda D.
        • Trentini F.
        • Guzzetta G.
        • Marziano V.
        • et al.
        Age-specific sars-cov-2 infection fatality ratio and associated risk factors, Italy, february to april 2020.
        Euro Surveill. 2020; 25: 2001383https://doi.org/10.2807/1560-7917.ES.2020.25.31.2001383