SARS-CoV-2 detection, viral load and infectivity over the course of an infection

Abstract

Objectives: To summarise the evidence on the detection pattern and viral load of SARS-CoV-2 over the course of an infection (including any asymptomatic or pre-symptomatic phase), and the duration of infectivity. Methods: A systematic literature search was undertaken in PubMed, Europe PubMed Central and EMBASE from 30 December 2019 to 12 May 2020. Results: We identified 113 studies conducted in 17 countries. The evidence from upper respiratory tract samples suggests that the viral load of SARS-CoV-2 peaks around symptom onset or a few days thereafter, and becomes undetectable about two weeks after symptom onset; however, viral loads from sputum samples may be higher, peak later and persist for longer. There is evidence of prolonged virus detection in stool samples, with unclear clinical significance. No study was found that definitively measured the duration of infectivity; however, patients may not be infectious for the entire duration of virus detection, as the presence of viral ribonucleic acid may not represent transmissible live virus. Conclusion: There is a relatively consistent trajectory of SARS-CoV-2 viral load over the course of COVID-19 from respiratory tract samples, however the duration of infectivity remains uncertain.

SARS-CoV-2 Viral Load, IFNλ Polymorphisms and the Course of COVID-19: An Observational Study

“…Data on the relationship between viral load and clinical outcome are still scarce, including viral load profiles at different times after diagnosis. A recently published review reports that the highest viral loads are detected at the time of symptom onset and generally decrease within one to three weeks after [ 16 ]. However, no clear evidence is available relating the infectivity to the presence of viral RNA detected with the rRT-PCR, as this does not indicate the presence of a live virus.…”

A needle in the haystack? Assessing the significance of envelope (E) gene-negative, nucleocapsid (N2) gene-positive SARS-CoV-2 detection by the Cepheid Xpert Xpress SARS-COV-2 assay

“…The duration of viral RNA detection among pre-symptomatic and asymptomatic patients varies widely among the literature published to date [ 8 , 9 ], however positivity can persist for several weeks [ 10 ]. Importantly, 34.1 % of patients with E-,N2+ results had a previous diagnosis of COVID-19 and we observed an E-,N2+ result in a patient with an initial positive result obtained 71 days prior (e = 26.7; N2 = 29.0).…”

Risikostratifizierung von Notfällen während der COVID-19-Pandemie in der Zentralen Notaufnahme

“…Die aktuelle Entwicklung von Point-of-Care und automatisierten Testverfahren [ 16 , 17 ] hat hier zu einer erheblichen Beschleunigung der diagnostischen Prozessabläufe geführt. Dennoch gelingt der Nachweis der SARS-CoV-2-Infektion nur in der replikativen Phase der viralen Infektion, da die Kopienzahl im Verlauf der SARS-CoV-2-Infektion sinkt [ 18 ]. Auch können durch die RT-PCR nicht alle Erkrankten identifiziert werden [ 12 ], wie die klinische Studie bei 138 hospitalisierten COVID-19-Patienten in Wuhan gezeigt hat.…”