Analysis from our political correspondent Harry Horton.
Yorkshire and the Humber has the highest proportion of people with Covid-19 antibodies in England, according to the Office for National Statistics.
An estimated 16.8% of people would have tested positive for SARS-CoV-2 in December - more than one in six.
In England, the figure is 12.1%, or one in eight people.
The data is only available at a regional level at this stage, so it's hard to pick out towns and cities with particularly high levels. But we do know that whilst infection levels dropped significantly in the South of England over the summer and autumn of 2020, they remained relatively high in the North. So the data isn't surprising.
West Yorkshire and South Yorkshire were hotspots for the virus for many months, and everywhere from York to Harrogate to Boston has seen huge spikes in recent weeks.The high level of antibodies should mean there's more Covid-19 immunity in the region - although there's no data to suggest immunity lasts longer than six months, and scientists don't know for sure whether immune people can still transmit the virus.
The data is from December - so won't take into account the surge in infections seen nationally over Christmas and New Year.
Meanwhile more than half of over-80s in Yorkshire & the North East have received at least one coronavirus vaccine dose. Along with health and care workers, it means around eight per cent of the region has been vaccinated.
The antibody data - along with the fast-paced vaccination programme - is encouraging news. But it could still take weeks - perhaps months - for the growing numbers of antibodies to have an impact on reducing deaths.