Ranks US Census tracts based on 15 social factors that are categorized into four themes. These four themes and the indices that comprised them were:

(1) socioeconomic status: below 150% poverty, unemployment, housing cost burden, no high school diploma, no health insurance;

(2) household characteristics: aged 65 and older, aged 17 or younger, those with disabilities, single-parent household;

(3), minority status and language: racial and ethnic residential categorizations, aged 5 or older who speaks English less than well; and

(4) housing and transportation: multi-unit structure, mobile homes, crowding, group quarters, and no vehicle.

SVI scores are percentiles. These are created by first adding all the SVI component scores for a census tract. That total is then ranked against all other tract totals and assigned a percentile ranking.

The total SVI score ranged from 0.00 (least vulnerable) to 1.00 (most vulnerable) with a higher score reflecting a more vulnerable Census tract for a given participant’s address.

Participants' study visit year is used to determine the year of SVI data linked to their geocoded address. The first year that a valid address is available to be geocoded for a participant once enrolled in the parent study is referred to as the participant's "geocoded baseline (GBL)". GBL is the same as parent study baseline for all participants except for some AACore participants for which address was not collected at the time of parent study enrollment.