“This recombinant (XD) exhibits immune escape properties similar to Omicron, while its behavior in mice expressing the human ACE2 receptor is more similar to Delta.”
For XD cases: “The median age was 32.5 years (IQR 19.75-44.75), which was similar to Omicron cases (35 years), however, significantly more XD cases were below 20 years of age (25.7%) compared to Omicron cases (11.3%, p= 0.026, Extended Data Fig. 2b).
Only two XD cases reported a previous SARS-CoV-2 infection (5.6%, Table 1), fewer than for Omicron (14%). No XD case was over 70 years old, and no risk factor was reported. Only 6% of recombinant cases were unvaccinated (vs 27% for Omicron cases), and 30% had received three doses (vs 8%), but the overall vaccination coverage of the population was different between the XD and Omicron study periods.
All XD cases reported here from France were symptomatic and most reported symptoms were headache (61.1%), asthenia/fatigue (58.3%), cough (44.4%), fever (38.9%) and myalgia (33.3%, Extended Data Fig. 2b). The main differences compared to Omicron cases were the higher rates of ageusia (odds ratio OR 2.71 [1.064-6.514], p=0.024) and anosmia (OR 1.98 [0.66-5.251], p = 0.18). Two XD cases were hospitalized, one for unrelated causes, but for less than 24h and without intensive care admission.”
“With the XD virus, we did not observe weight loss (in mice) during the first 5 dpi, but all mice deteriorated rapidly between day 5 and 8 and died or had to be euthanized by day 9. Clinical scores followed the same progression and delayed onset in XD- compared with AY.4-infected mice”
** Can we avoid downplaying this variant as “mild” until we have more evidence? The 100% symptomatic infection rate could mean it is very far from mild despite the lack of hospitalizations and deaths reported in this preprint **