URL
https://elifesciences.org/articles/60122
Type d’article
Article peer-reviewed
Thème
Immunité
Que retenir de cet article, en 1-2 phrases ?
This article gathers data (from 21 articles available in May 2020) on RNA shedding and antibody dynamics, and uses reasonable assumptions and procedures to combine these datasets to estimate overall dynamics. The authors give typical timescales of RNA shedding, seroconversion, and estimate the person-to-person variability.
Objectifs de l’étude / Questions abordées
The objective of this article is to gather data in the literature on time courses of RNA shedding and antibody detection, and to fit reasonable models to obtain their typical time course and estimate the person-to-person variation.
Méthode
The authors first look in the literature (up to May 1st 2020) for patient data on RNA shedding and antibody detection, when days since symptom onset are documented. They use data from 21 studies. To estimate the distribution of the time to seroconversion, the authors use a procedure where they use grouped data from cohorts as distributions from which they randomly sample. For the probability of RNA, IgM and IgG detection at a given day post onset, the authors have to interpolate some data, as there are gaps in sampling. For antibody level kinetics, they fit the level of antibody by a Gompertz fonction a exp(-b exp(-ct)), and use the resulting fit values to infer a population distribution of the parameters, using Bayesian Markov Chain Monte Carlo inference.
Résultats principaux
Seroconversion of both IgG and IgM occurs around 12 days post-symptom onset , but with high person-to-person variability (standard deviation of the order of 6 days). The authors compare different antigen targets, and patients with different levels of disease severity, and they show no clear association between antigen targets and disease severity. IgG and IgM detection probabilities increase from roughly 10% at symptom onset to close to 100% by day 22, after which IgMs wane while IgGs remain reliably detectable up to 2 months (beyond which the authors do not have enough data points to conclude). RNA detection probability decreases from roughly 90% to zero by day 30, and is highest in the lower respiratory tract, lowest in the upper respiratory tract , intermediate in feces.
Commentaire/brève évaluation
This article is useful in combining data in the literature to get a clearer picture of RNA shedding and antibody dynamics. The data and the code used are available as supplementary material. In elife, it is possible to read the main comments that were raised by the reviewers and resolved for eventual acceptance : the article has been improved by better detailing how literature was selected, and fixing some issues with the fitting procedure. It may have been interesting to comment further on the few data points about neutralizing antibodies, or the differences between the datasets and possible issues, but this is clearly not the focus of this article.