We find no evidence (for both risk of hospitalisation attendance and symptom status) of Omicron having different severity from Delta, though data on hospitalisations are still very limited. There are several limitations of this analysis. While case numbers are increasing quickly, there are still limits in our ability to examine interactions between the variables considered. The distribution of Omicron differed markedly from Delta across the English population at the time this analysis was conducted, likely due to the population groups in which it was initially seeded, which increases the risks of confounding in analyses. SGTF is an imperfect proxy for Omicron, though SGTF had over 60% specificity for Omicron over the date range analysed in the SGTF analysis (and close to 100% by 10th December). Intensified contact tracing around known Omicron cases may have increased case ascertainment over time, potentially introducing additional biases. Our analysis reinforces the still emerging but increasingly clear picture that Omicron poses an immediate and substantial threat to public health in England and more widely