key: cord-0746253-jq974wow
authors: El-Saed, Aiman; Alshamrani, Majid M.
title: RE: COVID-19 and healthcare workers: A systematic review and meta-analysis
date: 2021-03-17
journal: Int J Infect Dis
DOI: 10.1016/j.ijid.2021.03.029
sha: ab8139e07d28de72c5cd596a3291fdef1e79103d
doc_id: 746253
cord_uid: jq974wow

nan

a number of systematic reviews about the risk of COVID-19 among HCWs at global level.

Nevertheless, we believe that the percentage of positive COVID-19 testing calculated by the study and has been referred to as "prevalence" is extremely inaccurate and misleading. As per authors, the percentage of positive COVID-19 testing was estimated at 51.7% after combining data from 28 studies including 119,883 HCWs. However, using the data presented in Table 1 , the percentage of positive COVID-19 testing should be 11.7% (14,047 out of 119842 HCWs) not 51.7%. Additionally, the denominators of the two reports that contributed 78% of the positive HCWs included in the study were inaccurately recorded (Zheng et al., 2020; CDC COVID-19 Response Team, 2020). For example, the denominator of the Zheng and colleague study that has been recorded as 2457 HCWs in Table 1 was estimated at 117,100 HCWs in the original study, with an overall prevalence 2.1% (Zheng et al., 2020) . Similarly, the denominator of the study done by the US Centers for Disease Control and Prevention (CDC) that has been recorded as 8495 HCWs in Table 1 was not actually defined in the original report (CDC COVID-19

Response Team, 2020). The report estimated the percentage of positive HCWs out of all positive COVID-19 results (19%) and not the HCWs force in the US, which is estimated to be over 18 million workers. Therefore, the CDC report is not probably suitable for the inclusion in prevalence calculation. If the prevalence is recalculated after fixing the denominator of Zheng and colleague study (Zheng et al., 2020) and removing the CDC report (CDC COVID-19

Response Team, 2020), the true prevalence will be further reduced to 2.5% (5,552 out of 223,083 HCWs).

The overestimation of COVID-19 positivity has been repeated to some extent in the rates of hospitalization and mortality reported by Gholami and colleagues (Gholami et al., 2021) .

Using the data presented in Table 6 , the rates of hospitalization and mortality should be 8.2% and 0.6% and not 15.1% and 1.5%, respectively. Additionally, 18% of the hospitalization data and 33% of mortality data presented in Table 6 were derived from early Chinese studies that include only hospitalized or dead HCWs, respectively. Therefore not suitable for inclusion in the prevalence calculation. Additionally, the denominator was wrongly recorded in some studies (Zhan et al., 2020; . For example, the denominator for the 23 deaths in Zhan and colleague study was 3387. Therefore, the mortality was actually 0.7% and not 100% as mentioned in Table 6 (Zhan et al., 2020) . Removing studies that did not report denominator and fixing the wrong denominator will result in further reduction of the true rates of hospitalization and mortality to 6.8% and 0.4%, respectively.

Finally, future systematic reviews and meta-analysis on COVID-19 morbidity and mortality among HCWs should clearly differentiate between studies using reverse-transcription polymerase chain reaction (RT-PCR) and antibody testing (IgM and IgG) in confirming cases.

Furthermore, the data should be presented for symptomatic, asymptomatic, and exposed HCWs separately. 

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