The need for universal health care in the United States is more urgent than ever.

Universal health care would be an improvement over the current US health care system in terms of economics, access to care, and quality of care.

The second sentence makes an assertion about health care that is focused on three main subject areas (economics, access, and quality). The other statement makes a broad claim that is too vague for an effective thesis.

For more help, see section MLA-1a.