What's the case rate per 100K at the population level there?
Edit: actually, didn't find exactly that table, but did find a section in the doc you link, https://assets.publishing.service.gov.uk/government/uploads/..., on page 14, that shows vaccine effectiveness remains against symptomatic disease as a result of a study against delta and omicron both. But I would love to see the overall case rate to know about asymptomatic disease too.
The % per 100k is available p40 of the same pdf. But I find that much harder to read given that the size of the vaxxed and unvaxxed populations vastly differ.
The table on page 40 is consistent with US data, where case rates at the population. It says to read in conjunction with pages 32 to 34, which basically says "stats won't be as accurate as formal assessment of vaccine effectiveness, please see the formal data." The formal data suggests effectiveness against transmission. The raw cases-per-100k numbers agree. Yet you latch onto a different number - another one that the report says isn't authoritative for those purposes either - to claim the data shows ineffectiveness! That seems backward.
You had the same outcome in November, i.e. pre-Omicron.