The curious change in relationship between 999 COVID calls and COVID deaths

 

I have previously reported on the strange discrepancy between COVID 'cases' and COVID-related 999 calls/triages. 

With the massive January 2021 surge in COVID classified deaths I've been looking at the relationship between death counts (reported at https://coronavirus.data.gov.uk) and the 999 triages and calls (reported at https://digital.nhs.uk/dashboards/nhs-pathways

The problem with the 999 data is that for many regions (including London) it does not include all 999 ambulance service calls related to COVID. But, for certain areas such as the West Midlands, the 999 calls data does include the 999 ambulance service calls*. So using the filtering option to display only the plot of 999 calls for the West Midlands NHS authorities, it is possible to do a complete comparison to deaths in the same area as shown in the diagram above. 

I welcome any explanation for why the daily ratio between 999 COVID calls and deaths was consistently about 3 to 1 during 2020, but suddenly became 1:1 from the beginning of 2021.

*It is, however, important to note that the national pattern for both 999 calls and triages (including areas like London that do not include ambulance data) is actually almost identical in shape. The national deaths plot trend is also almost identical in shape as can be seen here:

As usual all the usual caveats discussed here apply.