Spread of the Delta variant, vaccine effectiveness against PCR-detected infections and within-host viral load dynamics in the community in France

François Blanquart (1) , Clémence Abad , Joevin Ambroise (2) , Mathieu Bernard (3) , Gina Cosentino (4) , Jean-Marc Giannoli (5) , Florence Débarre (1)

1 iEES Paris - Institut d'écologie et des sciences de l'environnement de Paris
2 BPO-BIOEPINE- Biogroup - Plateau technique Chocolaterie, Levallois-Perret, France
3 BIOLITTORAL-Biogroup - Plateau technique la Bastide, Sanary sur Mer, France
4 2I - Infection et inflammation
5 DYOMEDEA-NEOLAB-Biogroup-Plateau technique de la Sauvegarde, Lyon 9 France

We use a large number of SARS-CoV-2 PCR tests in the community in France from 15th May 2021 to 7th July 2021 and infer 76% vaccine effectiveness against PCR detected infection, similar effectiveness against Delta and previous variants, a +67% to +217% transmission advantage for Delta depending on the region, and a larger viral load at symptom onset (-2.4 Ct) for Delta variant infections.

Mots clés: covid-19; SARS-CoV-2; Delta; viral load; transmissibility

Domaines: Sciences du Vivant [q-bio]; Génétique des populations [q-bio.PE]; Santé publique et épidémiologie

François Blanquart, Clémence Abad, Joevin Ambroise, Mathieu Bernard, Gina Cosentino, et al.. Spread of the Delta variant, vaccine effectiveness against PCR-detected infections and within-host viral load dynamics in the community in France. 2021. ⟨hal-03289443⟩