The phrase "affecting almost all" is correct and usable in written English.
It can be used to describe a situation or phenomenon that has an impact on a large majority of a group or population.
Example: "The new policy is affecting almost all employees in the organization, leading to significant changes in workflow."
Alternatives: "impacting nearly everyone" or "influencing most individuals".
An era of amalgamation and expansion ensued, affecting almost all institutions.
While recalls of consumer electronics and other products are quite common, affecting almost all major manufacturers including Apple, this is the largest-scale product defect Samsung has had in recent memory.
He is to take over from the departing party secretary, Hu Jintao, part of a broad transition of power affecting almost all senior positions in the party and government.
Leptospirosis is globally important infectious disease affecting almost all mammals.
Previous studies have revealed complex genetic aberrations affecting almost all chromosomes with up- and down-regulation of several genes in this subtype of CTCL.
Soil texture (relative proportions of soil particles of varied sizes) is a fundamental soil physical property affecting almost all other soil physical properties and processes of agricultural, environmental and engineering importance.
Fire affects almost all of them however, at some scale!
This is not surprising, because they affect almost all of us occasionally.
Some mutualistic relationships are so pervasive that they affect almost all life-forms.
The foundation cites estimates that 1 to 2 percent of professional musicians are known to be affected, almost all of them classically trained and most of them male.
THE revised zoning adopted for Park Slope last April affects almost all the blocks from Warren Street south to 15th Street and from Third Avenue to Prospect Park, excluding only a manufacturing zone nearer the Gowanus Canal.
