Last night Microsoft released KB 4056894, the 2018-01 Security Monthly Quality Rollup for Windows 7. Spurred by early disclosure of the Meltdown and Spectre vulnerabilities, Microsoft has done yeoman work getting the software part of the patches pushed out the Automatic Update chute.
That said, Windows patches are only part of a very formidable picture.
Where we stand with Windows patches
As of this morning, all of the supported versions of Windows have Meltdown-related patches, except for Windows 8.1. In particular: