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Viral load dynamics and disease severity in patients infected with SARS-CoV-2 in Zhejiang province, China, January-March 2020: retrospective cohort study

BMJ 2020; 369 doi: https://doi.org/10.1136/bmj.m1443 (Published 21 April 2020) Cite this as: BMJ 2020;369:m1443

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Re: Concrete objectives on discrete data are a prerequisite for a scientific publication

Dear Editor,

Zheng et al have given an explanation for the confusing points we raised (https://www.bmj.com/content/369/bmj.m1443/rr-1) in their published article [1]. But the authors of the study say that there is no problem with the data they published.

Their work relies on disease progression and virus isolation/detection in various samples with respect to ‘days’. Therefore, a single day difference will ultimately have to change the whole scenario. Therefore, we raised this issue but the authors still stand by what they have published instead of noting the downside of the article.

In the first place, in their response, the authors say that data was based on the admitted patients from ‘19 January 2020 to 15 February 2020’ and ‘followed before discharge from the baseline date to 20 March 2020’; the later piece, is mentioned nowhere in the article, and thus the article is lacking clarity. This should have been mentioned in the method section and that’s what materials and methods section is meant for.

Responding to contradiction in number of days in supplementary figure 2 from the body of the article, the authors say “Days after Symptom Onset” but not “Days since Admission”, though in the article, it is mentioned that ‘supplementary figure S2 shows the daily collection of different sample types’. This is what exactly we understand that S2 figure is about days of collection of samples from admitted patients, irrespective of the admission and/or symptoms onset dates. Here, the word ‘day’ is important because the figure is about days of collection of samples from patients, starting from day 1, to 66. It means that, in total 66 days make the duration of the study, contrary to what is mentioned in abstract; January 19 to March 20 (62 days in total). This is a clear difference in total number of days and that affects the overall conclusion of the study.

Last, according to their response, ‘as for the four months mentioned in the summary, we refer to the period from December 2019 when the outbreak started’. Well, first, as for the record, the infection in Zhejiang province started in January [2], not in December, so this claim stands null and void, as clearly it is mentioned in the abstract that, ‘to evaluate viral loads at different stages of disease progression in patients infected with the 2019 severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) during the first four months of the epidemic in Zhejiang province, China’. Second, in case the authors are pointing to the coronavirus infection in China as a whole, then either the title or the abstract of the article should have been changed accordingly in order to disseminate information in a clear way to its readers because accuracy and precision in both numerical and linguistic sense brings quality to a scientific publication.

References:
1. Zheng S, Fan J. Yu F, et al., Viral load dynamics and disease severity in patients infected with SARS-CoV-2 in Zhejiang province, China, January-March 2020: retrospective cohort study. BMJ. 2020;369:m1443. doi: 10.1136/bmj.m1443
2. http://news.sina.com.cn/c/2020-01-21/doc-iihnzhha3956248.shtml

Competing interests: No competing interests

29 April 2020
Zulqarnain Baloch
Associate Professor
Amjad Ali, Assistant Professor, Biomedical Research Center, Northwest Minzu University, Lanzhou China
Biomedical Research Center, Northwest Minzu University, Lanzhou China
Biomedical Research Center, Northwest Minzu University, Lanzhou China