Table 1. Open in new tab Descriptive...

Characteristic	Preseason	After 2010–2011 TIV	End-of-Season
Descriptive characteristics
Demographics
Age, y	42 (12)	43 (12)	42 (12)
Age group
18–34 y	523 (37%)	279 (32%)	442 (35%)
35–49 y	508 (36%)	300 (35%)	449 (36%)
50–65 y	386 (27%)	286 (33%)	363 (29%)
Female	1132 (80%)	712 (82%)	1011 (81%)
White	1117 (79%)	696 (80%)	988 (79%)
Hispanic	165 (12%)	99 (11%)	144 (11%)
Health
Body mass index, kg/m²	28 (7)	29 (7)	28 (7)
Subjective health status (1–5)	4.1 (0.7)	4.1 (0.7)	4.1 (0.7)
HCP with high-risk condition(s) in 2009–2010	477 (34%)	316 (37%)	431 (34%)
Proxies for exposure to infection
HCP with ≥1 MAARI during A(H1N1)pdm09	176 (12%)	106 (12%)	164 (13%)
HCP with ≥1 MAARI during 2010–2011 influenza season	141 (10%)	89 (10%)	126 (10%)
Household size	2.1 (1.6)	2.1 (1.5)	2.1 (1.5)
Hours of direct patient care per week	32.6 (11.2)	31.8 (11.0)	32.4 (11.1)
Emergency department HCP	375 (26%)	202 (23%)	328 (26%)
Site
Kaiser Permanente Northwest, Oregon	418 (29%)	286 (33%)	395 (32%)
Scott & White Healthcare, Texas	999 (71%)	579 (67%)	859 (69%)
Timing of sera collection
No. of days from preseason serum to 2010–2011 TIV		15 (13)
No. of days from 2010–2011 TIV to post-TIV serum		31 (8)
No. of days from preseason to end-of-season serum			212 (15)
Influenza vaccination history
2009–2010 seasonal influenza (TIV or LAIV) vaccination	1007 (71%)	736 (85%)	894 (71%)
MIIV vaccination	598 (42%)	489 (57%)	545 (43%)
2010–2011 seasonal TIV vaccination	936 (66%)	865 (100%)	894 (71%)
Vaccination interactions for 2009–2010 and 2010–2011
No MIIV and No 2010–2011 TIV	398 (28%)	0 (0%)	304 (24%)
No MIIV and Yes 2010–2011 TIV	421 (30%)	376 (43%)	405 (32%)
Yes MIIV and No 2010–2011 TIV	83 (6%)	0 (0%)	56 (4%)
Yes MIIV and Yes 2010–2011 TIV	515 (36%)	489 (57%)	489 (39%)
Preseason serum HI antibody titer
GMT of A(H1N1)pdm09 HI titers	11.9 (3.1)	12.4 (3.1)	11.9 (3.1)
Ordinal^a A(H1N1)pdm09 HI level	1.3 (1.6)	1.3 (1.6)	1.2 (1.6)

Characteristic

Preseason

After 2010–2011 TIV

End-of-Season

Serum (n = 1417)

Serum (n = 865)

Serum (n = 1254)

Descriptive characteristics

Demographics

Age, y

42 (12)

43 (12)

42 (12)

Age group

18–34 y

523 (37%)

279 (32%)

442 (35%)

35–49 y

508 (36%)

300 (35%)

449 (36%)

50–65 y

386 (27%)

286 (33%)

363 (29%)

Female

1132 (80%)

712 (82%)

1011 (81%)

White

1117 (79%)

696 (80%)

988 (79%)

Hispanic

165 (12%)

99 (11%)

144 (11%)

Health

Body mass index, kg/m²

28 (7)

29 (7)

28 (7)

Subjective health status (1–5)

4.1 (0.7)

HCP with high-risk condition(s) in 2009–2010

477 (34%)

316 (37%)

431 (34%)

Proxies for exposure to infection

HCP with ≥1 MAARI during A(H1N1)pdm09

176 (12%)

106 (12%)

164 (13%)

HCP with ≥1 MAARI during 2010–2011 influenza season

141 (10%)

89 (10%)

126 (10%)

Household size

2.1 (1.6)

2.1 (1.5)

Hours of direct patient care per week

32.6 (11.2)

31.8 (11.0)

32.4 (11.1)

Emergency department HCP

375 (26%)

202 (23%)

328 (26%)

Site

Kaiser Permanente Northwest, Oregon

418 (29%)

286 (33%)

395 (32%)

Scott & White Healthcare, Texas

999 (71%)

579 (67%)

859 (69%)

Timing of sera collection

No. of days from preseason serum to 2010–2011 TIV

15 (13)

No. of days from 2010–2011 TIV to post-TIV serum

31 (8)

No. of days from preseason to end-of-season serum

212 (15)

Influenza vaccination history

2009–2010 seasonal influenza (TIV or LAIV) vaccination

1007 (71%)

736 (85%)

894 (71%)

MIIV vaccination

598 (42%)

489 (57%)

545 (43%)

2010–2011 seasonal TIV vaccination

936 (66%)

865 (100%)

894 (71%)

Vaccination interactions for 2009–2010 and 2010–2011

No MIIV and No 2010–2011 TIV

398 (28%)

0 (0%)

304 (24%)

No MIIV and Yes 2010–2011 TIV

421 (30%)

376 (43%)

405 (32%)

Yes MIIV and No 2010–2011 TIV

83 (6%)

0 (0%)

56 (4%)

Yes MIIV and Yes 2010–2011 TIV

515 (36%)

489 (57%)

489 (39%)

Preseason serum HI antibody titer

GMT of A(H1N1)pdm09 HI titers

11.9 (3.1)

12.4 (3.1)

11.9 (3.1)

Ordinal^a A(H1N1)pdm09 HI level

1.3 (1.6)

1.2 (1.6)

Characteristic	Preseason	After 2010–2011 TIV	End-of-Season
Descriptive characteristics
Demographics
Age, y	42 (12)	43 (12)	42 (12)
Age group
18–34 y	523 (37%)	279 (32%)	442 (35%)
35–49 y	508 (36%)	300 (35%)	449 (36%)
50–65 y	386 (27%)	286 (33%)	363 (29%)
Female	1132 (80%)	712 (82%)	1011 (81%)
White	1117 (79%)	696 (80%)	988 (79%)
Hispanic	165 (12%)	99 (11%)	144 (11%)
Health
Body mass index, kg/m²	28 (7)	29 (7)	28 (7)
Subjective health status (1–5)	4.1 (0.7)	4.1 (0.7)	4.1 (0.7)
HCP with high-risk condition(s) in 2009–2010	477 (34%)	316 (37%)	431 (34%)
Proxies for exposure to infection
HCP with ≥1 MAARI during A(H1N1)pdm09	176 (12%)	106 (12%)	164 (13%)
HCP with ≥1 MAARI during 2010–2011 influenza season	141 (10%)	89 (10%)	126 (10%)
Household size	2.1 (1.6)	2.1 (1.5)	2.1 (1.5)
Hours of direct patient care per week	32.6 (11.2)	31.8 (11.0)	32.4 (11.1)
Emergency department HCP	375 (26%)	202 (23%)	328 (26%)
Site
Kaiser Permanente Northwest, Oregon	418 (29%)	286 (33%)	395 (32%)
Scott & White Healthcare, Texas	999 (71%)	579 (67%)	859 (69%)
Timing of sera collection
No. of days from preseason serum to 2010–2011 TIV		15 (13)
No. of days from 2010–2011 TIV to post-TIV serum		31 (8)
No. of days from preseason to end-of-season serum			212 (15)
Influenza vaccination history
2009–2010 seasonal influenza (TIV or LAIV) vaccination	1007 (71%)	736 (85%)	894 (71%)
MIIV vaccination	598 (42%)	489 (57%)	545 (43%)
2010–2011 seasonal TIV vaccination	936 (66%)	865 (100%)	894 (71%)
Vaccination interactions for 2009–2010 and 2010–2011
No MIIV and No 2010–2011 TIV	398 (28%)	0 (0%)	304 (24%)
No MIIV and Yes 2010–2011 TIV	421 (30%)	376 (43%)	405 (32%)
Yes MIIV and No 2010–2011 TIV	83 (6%)	0 (0%)	56 (4%)
Yes MIIV and Yes 2010–2011 TIV	515 (36%)	489 (57%)	489 (39%)
Preseason serum HI antibody titer
GMT of A(H1N1)pdm09 HI titers	11.9 (3.1)	12.4 (3.1)	11.9 (3.1)
Ordinal^a A(H1N1)pdm09 HI level	1.3 (1.6)	1.3 (1.6)	1.2 (1.6)

Table 1.

Open in new tab

Descriptive Characteristics, Vaccination History, and 2009 A(H1N1) Pandemic Influenza Virus Hemagglutination Inhibition Antibody Seroresponse of Healthcare Personnel

Characteristic	Preseason	After 2010–2011 TIV	End-of-Season
Characteristic	Serum (n = 1417)	Serum (n = 865)	Serum (n = 1254)
Descriptive characteristics
Demographics
Age, y	42 (12)	43 (12)	42 (12)
Age group
18–34 y	523 (37%)	279 (32%)	442 (35%)
35–49 y	508 (36%)	300 (35%)	449 (36%)
50–65 y	386 (27%)	286 (33%)	363 (29%)
Female	1132 (80%)	712 (82%)	1011 (81%)
White	1117 (79%)	696 (80%)	988 (79%)
Hispanic	165 (12%)	99 (11%)	144 (11%)
Health
Body mass index, kg/m²	28 (7)	29 (7)	28 (7)
Subjective health status (1–5)	4.1 (0.7)	4.1 (0.7)	4.1 (0.7)
HCP with high-risk condition(s) in 2009–2010	477 (34%)	316 (37%)	431 (34%)
Proxies for exposure to infection
HCP with ≥1 MAARI during A(H1N1)pdm09	176 (12%)	106 (12%)	164 (13%)
HCP with ≥1 MAARI during 2010–2011 influenza season	141 (10%)	89 (10%)	126 (10%)
Household size	2.1 (1.6)	2.1 (1.5)	2.1 (1.5)
Hours of direct patient care per week	32.6 (11.2)	31.8 (11.0)	32.4 (11.1)
Emergency department HCP	375 (26%)	202 (23%)	328 (26%)
Site
Kaiser Permanente Northwest, Oregon	418 (29%)	286 (33%)	395 (32%)
Scott & White Healthcare, Texas	999 (71%)	579 (67%)	859 (69%)
Timing of sera collection
No. of days from preseason serum to 2010–2011 TIV		15 (13)
No. of days from 2010–2011 TIV to post-TIV serum		31 (8)
No. of days from preseason to end-of-season serum			212 (15)
Influenza vaccination history
2009–2010 seasonal influenza (TIV or LAIV) vaccination	1007 (71%)	736 (85%)	894 (71%)
MIIV vaccination	598 (42%)	489 (57%)	545 (43%)
2010–2011 seasonal TIV vaccination	936 (66%)	865 (100%)	894 (71%)
Vaccination interactions for 2009–2010 and 2010–2011
No MIIV and No 2010–2011 TIV	398 (28%)	0 (0%)	304 (24%)
No MIIV and Yes 2010–2011 TIV	421 (30%)	376 (43%)	405 (32%)
Yes MIIV and No 2010–2011 TIV	83 (6%)	0 (0%)	56 (4%)
Yes MIIV and Yes 2010–2011 TIV	515 (36%)	489 (57%)	489 (39%)
Preseason serum HI antibody titer
GMT of A(H1N1)pdm09 HI titers	11.9 (3.1)	12.4 (3.1)	11.9 (3.1)
Ordinal^a A(H1N1)pdm09 HI level	1.3 (1.6)	1.3 (1.6)	1.2 (1.6)

Characteristic	Preseason	After 2010–2011 TIV	End-of-Season
Characteristic	Serum (n = 1417)	Serum (n = 865)	Serum (n = 1254)
Descriptive characteristics
Demographics
Age, y	42 (12)	43 (12)	42 (12)
Age group
18–34 y	523 (37%)	279 (32%)	442 (35%)
35–49 y	508 (36%)	300 (35%)	449 (36%)
50–65 y	386 (27%)	286 (33%)	363 (29%)
Female	1132 (80%)	712 (82%)	1011 (81%)
White	1117 (79%)	696 (80%)	988 (79%)
Hispanic	165 (12%)	99 (11%)	144 (11%)
Health
Body mass index, kg/m²	28 (7)	29 (7)	28 (7)
Subjective health status (1–5)	4.1 (0.7)	4.1 (0.7)	4.1 (0.7)
HCP with high-risk condition(s) in 2009–2010	477 (34%)	316 (37%)	431 (34%)
Proxies for exposure to infection
HCP with ≥1 MAARI during A(H1N1)pdm09	176 (12%)	106 (12%)	164 (13%)
HCP with ≥1 MAARI during 2010–2011 influenza season	141 (10%)	89 (10%)	126 (10%)
Household size	2.1 (1.6)	2.1 (1.5)	2.1 (1.5)
Hours of direct patient care per week	32.6 (11.2)	31.8 (11.0)	32.4 (11.1)
Emergency department HCP	375 (26%)	202 (23%)	328 (26%)
Site
Kaiser Permanente Northwest, Oregon	418 (29%)	286 (33%)	395 (32%)
Scott & White Healthcare, Texas	999 (71%)	579 (67%)	859 (69%)
Timing of sera collection
No. of days from preseason serum to 2010–2011 TIV		15 (13)
No. of days from 2010–2011 TIV to post-TIV serum		31 (8)
No. of days from preseason to end-of-season serum			212 (15)
Influenza vaccination history
2009–2010 seasonal influenza (TIV or LAIV) vaccination	1007 (71%)	736 (85%)	894 (71%)
MIIV vaccination	598 (42%)	489 (57%)	545 (43%)
2010–2011 seasonal TIV vaccination	936 (66%)	865 (100%)	894 (71%)
Vaccination interactions for 2009–2010 and 2010–2011
No MIIV and No 2010–2011 TIV	398 (28%)	0 (0%)	304 (24%)
No MIIV and Yes 2010–2011 TIV	421 (30%)	376 (43%)	405 (32%)
Yes MIIV and No 2010–2011 TIV	83 (6%)	0 (0%)	56 (4%)
Yes MIIV and Yes 2010–2011 TIV	515 (36%)	489 (57%)	489 (39%)
Preseason serum HI antibody titer
GMT of A(H1N1)pdm09 HI titers	11.9 (3.1)	12.4 (3.1)	11.9 (3.1)
Ordinal^a A(H1N1)pdm09 HI level	1.3 (1.6)	1.3 (1.6)	1.2 (1.6)

Data are presented as mean (SD) or No. (%).

Abbreviations: GMT, geometric mean titer; HCP, healthcare personnel; HI, hemagglutination inhibition antibody; LAIV, live attenuated influenza vaccine; MAARI, medically attended acute respiratory illness; MIIV, 2009–2010 A(H1N1) pandemic monovalent inactivated influenza vaccine; TIV, trivalent inactivated vaccine.

^a Ordinal HI levels are represented with 0–9 levels based on log transformation of HI titers: Log₂ (HI titer/5).

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