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Review 2: "Is Higher Viral Load in SARS-CoV-2 Associated With Death?"

This study is potentially informative but the results should be approached with caution. The claim that high viral load indicates higher mortality is not fully supported. Multiple confounding variables have not been taken into account.

Published onSep 03, 2020
Review 2: "Is Higher Viral Load in SARS-CoV-2 Associated With Death?"

RR:C19 Evidence Scale rating by reviewer:

  • Potentially informative. The main claims made are not strongly justified by the methods and data, but may yield some insight. The results and conclusions of the study may resemble those from the hypothetical ideal study, but there is substantial room for doubt. Decision-makers should consider this evidence only with a thorough understanding of its weaknesses, alongside other evidence and theory. Decision-makers should not consider this actionable, unless the weaknesses are clearly understood and there is other theory and evidence to further support it.



The authors tried to show the relationship between SARS-CoV-2 viral load and risk of the disease’s progression. They quantified the amount of SARS-CoV-2 viral load of patients for a diverse range of COVID-19 severity (including mild, moderate and severe). The result showed that the viral load is highest among both the severe and mild patients (initial Ct of 21.5 and 22, respectively). Lowest virus load appeared in patients with moderate disease manifestation.

Besides, they also claimed that hospitalized patients (mainly from the moderate and severe patients) with COVID-19 had a prevalence of higher detectable SARS-CoV-2 plasma viral load but highest among those decease patients.

Without a doubt, the manuscript had presented some good data. However, from the data presented, I would like to share some of my concerns related to the facts given.

1. The authors claimed that they did lymphocyte counts and tested on some inflammatory markers, such as C-reactive protein and IL-6, but no supporting data is included in any part of the manuscript.

2. According to the authors, high viral loads of SARS-CoV-2 had also been detected in mild patients (who were not admitted). It might not explain the correlation between the viral load and the increasingly risk of mortality among patients. However, they may have some good explanations for the high viral loads in mild patient from immunological and pathological points of views.

3. The authors made a serious statement by saying that Ct value of less than 25 were consistent with high viral load in patients who were more likely to die during hospitalization. However, the mild patients (with Ct value of 22) had proven differently.

Therefore, with the above concerns, I don’t totally agree with the conclusion made from the manuscript and viral load alone does not seem to be an accurate predictor of mortality rates.

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