Warm weather will stop this thing before a vaccine is ready, most likely—so in Texas it should die on its own fairly quickly—but the next month will not be pretty....
Anybody below 32N lat can make D3. The best kind. 20-30m of sun at midday (around noon) will do the trick.
Don’t burn.
Don’t stay longer than 30m, you don’t make more after that.
If you can, flip like bacon to get max skin exposure. Be sure NOT to offend the neighbors though :)
That assertion is not proving out in locations that are already warm.