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Addendum - Corman Drosten Review Report by an International Consortium of Scientists in Life Sciences (ICSLS)

Borger, Pieter; Malhotra, Rajesh Kumar; Yeadon, Michael; Clare, Craig; McKernan, Kevin; Steger, Klaus; McSheehy, Paul; Angelova, Lidiya; Franchi, Fabio; Binder, Thomas; Ullrich, Henrik; Ohashi, Makoto; Scoglio, Stefano; Doesburg-van Kleffens, Marjolein; Gilbert, Dorothea; Klement, Rainer J.; Schruefer, Ruth; Pieksma, Berber W.; Bonte, Jan; Dalle Carbonare, Bruno H.; Corbett, Kevin P.; Kämmerer, Ulrike

Background:: After submitting our review report on Corman et al. (referred hereinafter as CD-report) and republishing it on a scientific preprint server ( and we offered the report for public discussion at on 27th November 2020. The scientific community provided additional literature, references, and analyses concerning the CD-report and the Corman et al. manuscript. Several “advocatus diaboli” confronted us with correct or assumed problems in our report. The most common critique of the CD-report was the lack of “wet lab” experiments to support our concerns over the technical flaws in the PCR protocol.

Aim: This vibrant debate on our CD report has provided additional information worthy of further
public documentation to address these critiques. We summarize the current published
knowledge of “wet lab testing”, routine diagnostic use and validation of the original
PCR-Protocol described by Corman et al. Further, this addendum highlights that independent
research groups (some of them with Corman and/or Drosten as author) also pointed out
important concerns with the original manuscript and Corman PCR protocol distributed by
the WHO. Many of these references were already provided by the authors of the original
CD-report but it is worth underscoring their relevance to the formation of our critiques of
the CD manuscript.

Methods: We searched the literature for ‘SARS-CoV-2 qPCR’ and ‘Corman’ or ‘Charité’. Then we
combined these references with those provided by other scientists working in relevant Life
Sciences/data analysis fields.
In the first section of the addendum, the publications will be discussed point by point,
highlighting their findings in relation to the CD-report. In a second section, additional aspects
about the Corman et al . publication are discussed. This spans a meta-analysis of the unusual
peer-review process, timeframes, and further technical vulnerabilities of the Corman et al .
An additional concern was raised about the CD-report regarding the discussion of
appropriate controls. We cite several studies that underscore the importance of internal
controls in assessing viral load and the lack of such internal controls in the Corman qPCR
method. These internal controls are required for normalizing swab sampling variance and they are critical for interpreting viral load. They are notably absent from the Corman PCR protocol. Several people also expressed confusion regarding the NCBI submissions provided
by Corman et al . The sequences provided lack two of the target gene sequences Corman et
al. claim to target. The only sequences referenced in the manuscript are listed ( KC633203,
KC633204, KC633201, GU190221, GU190222, GU190223) and none of these have sequences
that match their N and E gene primers. This not only brings their validation into question but
also prevents others from reproducing the work presented in Corman et al.

Results: We present 20 scientific publications providing ‘wet lab’ evidence of the performance of the
Corman et al. PCR protocol. Of those, 17 found problems with incorrect primer design
(mismatches, dimer formation, melting temperature) in the SARS-CoV-2 specific
“confirmatory” test named RdRp-PCR for “RNA-dependent RNA-polymerase” or the E-gene
These documented problems include:
● Documented primer dimers and False Positives in non-template controls (NTCs)
● Documented poor sensitivity and False Negatives compared to other assays
● No internal control to normalize the sample preparation variability and its impact on viral
load estimation
● No defined Ct for calling samples “Positive cases”
● Poorly documented positive controls and sequences used in their study

Conclusions: We believe the references provided in this addendum itemize the scientific consensus
evident in the literature regarding the flaws in the original PCR detection method for
SARs-CoV-2 published by Corman et al. . Further, since several important flaws were
published in peer-reviewed journals, the lack of correction of the original PCR protocol by
either Eurosurveillance or as an update in the Charité-WHO protocol brings into question the
scientific integrity of the authors of Corman et al. These references settle any remaining
debate that the Corman et al. manuscript should be retracted on technical grounds alone.
The rapidity of the peer-review and conflicts of interest are even more troubling.

This is an addendum to our report also published on Zenodo: 10.5281/zenodo.4298004
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