June 4, 2020

expert reaction to updated German preprint looking at the amount of virus from those with COVID-19 in different age groups

A previously posted preprint reporting on the amount of virus from those with COVID-19 in different age groups has been updated.

Prof Russell Viner, Professor of Adolescent Health at UCL Great Ormond Street Institute of Child Health, said:

“This work remains un-peer reviewed, however the authors appear to have provided more detail and attempted to respond to criticisms that their data in fact showed that viral load increases with age.

“The role that children and young people play in transmission of SARS-CoV-2 by is dependent upon multiple factors, including their risk of exposure to potential infection, their probability of being infected upon exposure (susceptibility), the extent to which they develop symptoms upon infection or remain asymptomatic, the extent to which they develop a viral load sufficiently high to transmit and their propensity for making potentially infectious contact with others, dependent upon numbers of social contacts across age-groups and behaviour during those contacts. Viral load per se is only a part of the story.

“The findings from this re-analysis tell us that some symptomatic children may have a viral load nearly as high as adults but it remains very unclear whether on average children and young people have lower or similar viral load to adults.  This new version shows findings from two samples tested using different methods, which produced differing results, leaving us rather little the wiser.

“We know that individual children can and do transmit SARS-CoV-2 and it is highly likely that some children with high viral loads are as infective as adults.  Whether children and young people as a population group transmit as much as adults remains very unclear.  Factors upstream from viral load such as susceptibility are important.  Lower susceptibility to SARS-CoV-2 infection in children, now shown in meta-analysis, likely means that fewer children have the opportunity to transmit their viral load.  However factors downstream, particularly social contacts and behaviour, may increase transmission at lower viral loads.  In the face of uncertainty we must continue to be cautious and assume the plausible pessimistic scenario i.e. that transmission amongst children is similar to that in adults, whilst gathering more evidence.”

Prof Kevin McConway, Professor Emeritus of Applied Statistics, The Open University, and Prof Sir David Spiegelhalter, Chair of the Winton Centre for Risk and Evidence Communication, University of Cambridge, said:

“We are pleased to see the new version of the preprint on viral load by Jones et al.  This revision is in our view considerably improved, and the authors have dealt with the three main statistical problems that we raised in our article on the first version.  They have also:

• made it clearer that there are unavoidable issues with the data due to it coming from tests carried out in clinical practice rather than being collected for research purposes;
• explained why it is still important and useful to present the data and analyses, because better data are not available;
• made it clearer that this is a preprint, that the research has not yet been evaluated by other scientists or clinicians, and that it should not yet be used to guide clinical practice.

“We welcome this much-improved revision, and although we may make further comments to the authors through the usual channels for commenting on preprints, we intend to make no other statement about the revised version.

“Originally, our statement included some concerns about the final sentence in the Abstract, which was not in accord with other statements in this version of the preprint.  After the authors had read that version of our statement, they agreed that the sentence did not express what they had intended to express, and have already made a small change to the sentence to make it match their intended meaning and to remove the apparent contradiction.  (The uploaded version has already been modified, ed.)  This is, we feel, a good example of how science, and communication and collaboration between scientists, should work.”

Blog by David Spiegelhalter and Kevin McConway published on 25 May 2020 about the original version of the preprint: https://medium.com/@d_spiegel/is-sars-cov-2-viral-load-lower-in-young-children-than-adults-8b4116d28353

https://virologie-ccm.charite.de/fileadmin/user_upload/microsites/m_cc05/virologie-ccm/dateien_upload/Weitere_Dateien/Charite_SARS-CoV-2_viral_load_2020-06-02.pdf

All our previous output on this subject can be seen at this weblink:

www.sciencemediacentre.org/tag/covid-19

Declared interests

None received.