Table 1. Propensity score matching results, all factors were significantly different between the 2 cohorts prior to matching (p<0.0001).

				Before Matching					After Matching
Codes	Demographics	Mean +/-SD	Patients	% of Cohorts	p-Value	Std Dev	Mean +/- SD	Patients	% of Cohorts	p-Value	Std Dev
AI	Age at Index	43.3 +/- 22.4 $52.6+/-24.6$	2,814,377 $37,377$	100% $100\%$	<0.0001	0.3959	52.5 +/- 24.6 52.6 +/- 24.6	37,377 $37,377$	100% $100\%$	0.7967	0.0019
2186–5	Not Hispanic or Latino		1,768,612 $32,018$	62.842% $85.662\%$	<0.0001	0.5406		32,085 $32,018$	85.842% $85.662\%$	0.4833	0.0051
2106–3	White		1,787,611 $28,969$	63.517% $77.505\%$	<0.0001	0.3104		29,037 $28,969$	77.687% $77.505\%$	0.5508	0.0044
F	Female		1,552,735 $21,694$	55.172% $58.041\%$	<0.0001	0.0579		21,696 $21,694$	58.046% $58.041\%$	0.9882	0.0001
M	Male		1,235,524 $15,672$	43.9% $41.93\%$	<0.0001	0.0398		15,666 $15,672$	41.913% $41.93\%$	0.9645	0.0003
2054–5	Black or African American		379,423 $4,214$	13.42% $11.274\%$	<0.0001	0.0671		4,204 $4,214$	11.248% $11.274\%$	0.9079	0.0008
UN	Unknown Ethnicity		776,781 $3,127$	27.6% $8.366\%$	<0.0001	0.5173		3,114 $3,127$	3.331% $8.366\%$	0.8635	0.0013
2131–1	Unknown Race		579,997 $3,040$	20.608% $8.133\%$	<0.0001	0.3614		3,054 $3,040$	8.171% $8.133\%$	0.8516	0.0014
2135–2	Hispanic or Latino		268,984 $2,232$	9.557% $5.972\%$	<0.0001	0.1343		2,178 $2,232$	5.827% $5.972\%$	0.4019	0.0061
2028–9	Asian		49,119 $769$	1.745% $2.057\%$	<0.0001	0.0229		736 $769$	1.969% $2.057\%$	0.3902	0.0063
1002–5	American Indian or Alaska Native		12,626 $226$	0.449% $0.605\%$	<0.0001	0.0216		209 $226$	0.559% $0.605\%$	0.4137	0.006
2076–8	Native Hawaiian or Other Pacific Islander		5,601 $159$	0.199% $0.425\%$	<0.0001	0.0406		137 $159$	0.367% $0.425\%$	0.2001	0.0094
Codes	Diagnoses	Mean +/-SD	Patients	Percent of Cohorts	p-Value	Std Dev	Mean +/- SD	Patients	% of Cohorts	p-Value	Std Dev
Z00-Z99	Factors Influencing Health Status & Contact with Health Services		1,231,075 $37,146$	43.742% $99.382\%$	<0.0001	1.5668		37,146 $37,146$	99.382% $99.382\%$	1.0000	<0.0001
M00-M99	Musculoskeletal Disease		691,394 $22,362$	24.567% $59.828\%$	<0.0001	0.7643		22,382 $22,362$	59.882% $59.828\%$	0.8814	0.0011
I10-I16	Hypertension		467,590 $17,654$	16.614% $47.232\%$	<0.0001	0.6953		17,679 $17,654$	47.299% $47.232\%$	0.8547	0.0013
E08-E13	Diabetes Mellitus		206,563 $8,352$	7.34% $22.345\%$	<0.0001	0.4318		8,348 $8,352$	22.335% $22.345\%$	0.972	0.0003
E65-E68	Overweight/Obesity		185,395 $6,695$	6.587% $17.912\%$	<0.0001	0.3507		6,619 $6,695$	17.709% $17.912\%$	0.4675	0.0053
I25	Heart Disease		122,995 $5,409$	4.37% $14.471\%$	<0.0001	0.3511		5,350 $5,409$	14.314% $14.471\%$	0.5387	0.0045
I50	Heart Failure		81,330 $3,894$	2.89% $10.418\%$	<0.0001	0.3056		3,849 $3,894$	10.298% $10.418\%$	0.5891	0.0040
J44	COPD		72,204 $3,582$	2.566% $9.583\%$	<0.0001	0.2970		3,539 $3,582$	9.468% $9.583\%$	0.5922	0.0039

Following matching, there were no significant differences between factors (p>0.05). (Black font = No Influenza Vaccine Cohort, Blue Font = Influenza Vaccine Cohort).