Phase 1B definitions for Texas are out. Phase 1B may start "in the coming weeks", but no specific date yet:
https://www.dshs.state.tx.us/coronavirus/immunize/vaccine/EVAP-Phase1B.pdf
Ages 65 and over, you're in...
Ages 16-64 can get a shot if you have one of these:
Cancer
Chronic kidney disease
COPD (chronic obstructive pulmonary disease)
Heart conditions, such as heart failure, coronary artery disease or cardiomyopathies
Solid organ transplantation
Obesity and severe obesity (body mass index of 30 kg/m2 or higher)
Pregnancy
Sickle cell disease
Type 2 diabetes mellitus
There is some vague language in the definition that could be interpreted several ways, but that's the basic idea.
About 70% of the deaths so far have been in the 65 and older group, so we may not see cases drop as fast from this allocation but we should see deaths significantly drop. I would think this will also lower the burden on hospitals faster, but younger groups will still be passing it around.