Spatial and temporal dynamics of SARS-CoV-2 in COVID-19 patients: A systematic review and meta-analysis

Abstract

Background The spatial and temporal dynamics of SARS-CoV-2 have been described in case series and retrospective studies. In this study, we provide a coherent overview of the duration of viral detection and viral RNA load in COVID-19 patients, stratified by specimen type, clinical severity, and age. Method We systematically searched PubMed/MEDLINE and Cochrane review database for studies published between 1.11.2019 and 23.04.2020. We pooled the data of selected studies (22/7226 (650 patients) for meta-analysis) to estimate duration of viral detection and visualized viral load over time. Findings Our analysis showed consistent viral detection from specimen from the upper respiratory tract (URT), the lower respiratory tract (LRT), and faeces, irrespective of the clinical severity of COVID-19. Our analysis suggests that SARS-CoV-2 persists for a longer duration in the LRT compared to the URT in adult patients (5•7 days in mild; 5•9 days in moderate-severe patients). The differences in the duration of viral detection between mild and moderate-severe patients is limited in the LRT, but an indication of longer duration of viral detection for moderate-severe patients was observed in feces (15 days in mild vs. 21 days in moderate-severe patients) and the URT (12 days in mild vs. 16 days in moderate-severe patients). Further, viral load was demonstrated to peak in earlier stages of infection in the URT compared to LRT. Interpretation This review may aid mathematical modelling and help in defining appropriate endpoints for clinical trails with antivirals in COVID-19. Funding The project has received funding support from Innovation Fund Denmark.

Performance of at-home self-collected saliva and nasal-oropharyngeal swabs in the surveillance of COVID-19

“…These results stress the importance of early diagnosis of COVID-19, in which a sample should be collected within the first days of symptoms, thus minimizing the loss of sensitivity of the molecular diagnosis [ 26 ]. Different studies have analyzed the SARS-CoV-2 shedding in different biologic specimens, reporting that viral loads from upper respiratory tract samples peak within a week of symptom onset and follow a relatively consistent downward trajectory [ 27 ]. The viral load in other biologic specimens, including saliva, follows the same trajectory [ 28 ].…”

Prospects for a safe COVID-19 vaccine

“…The reason for higher anti-spike protein antibody responses in severe COVID-19 disease is not clear, but may be due to higher viral loads in severe disease (88). Indeed, studies have demonstrated that the nasopharyngeal SARS-CoV-2 viral load was higher in elderly patients and in severe disease compared to mild disease (89,90). However, in other studies, no association was found between nasopharyngeal viral load and disease severity (91).…”

Role of favipiravir in the treatment of COVID-19

“…Viral load in the upper respiratory tract (URT) peaks early in mild patients (4 days) as compared to in moderate-severe patients (8 days). Similarly, viral load in lower respiratory tract (LRT) peaks early in mild patients (6 days) than in moderate-severe patients (11 days); however, variability in data can occur because of inconsistency in cycle threshold (Ct) value of gene, the use of different RT-PCR or RNA extraction kits, and combining samples to URT and LRT specimen ( Figure 1 ) ( Weiss et al, 2020 ).

Figure 1 Average viral load and disease severity ( Weiss et al, 2020 ).

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