Baseline Characteristics of Trial Participants Overall and by Vaccine, Modified Intention-to-Treat Population, 2022–2023 Influenza Season (N = 3952)
| Characteristic . | All (n = 3952) . | SD IIV (n = 1976) . | RIV (n = 1976) . | |||
|---|---|---|---|---|---|---|
| No. . | (Column %) . | No. . | (Column %) . | No. . | (Column %) . | |
| Age, y | ||||||
| 18–49 | 3291 | (83.3) | 1646 | (83.3) | 1645 | (83.3) |
| 50–64 | 661 | (16.7) | 330 | (16.7) | 331 | (16.8) |
| Race | ||||||
| American Indian or Alaska Native | 29 | (0.7) | 15 | (0.8) | 14 | (0.7) |
| Asian | 782 | (19.8) | 392 | (19.8) | 390 | (19.7) |
| Black or African American | 460 | (11.6) | 228 | (11.5) | 232 | (11.7) |
| Native Hawaiian or Other Pacific Islander | 4 | (0.1) | 3 | (0.2) | 1 | (0.1) |
| White | 2348 | (59.4) | 1175 | (59.5) | 1173 | (59.4) |
| Multiracial | 148 | (3.7) | 75 | (3.8) | 73 | (3.7) |
| Declined/missing | 181 | (4.6) | 88 | (4.5) | 93 | (4.7) |
| Ethnicity | ||||||
| Hispanic or Latino/a | 600 | (15.2) | 299 | (15.1) | 301 | (15.2) |
| Not Hispanic or Latino/a | 3274 | (82.8) | 1641 | (83.1) | 1633 | (82.6) |
| Declined/missing | 78 | (2.0) | 36 | (1.8) | 42 | (2.1) |
| Gender | ||||||
| Female | 2476 | (62.7) | 1221 | (61.8) | 1255 | (63.5) |
| Male | 1406 | (35.6) | 722 | (36.5) | 684 | (34.6) |
| Transgender/other | 24 | (0.6) | 12 | (0.6) | 12 | (0.6) |
| None of these | 46 | (1.2) | 21 | (1.1) | 25 | (1.3) |
| Missing | 0 | (0.0) | 0 | (0.0) | 0 | (0.0) |
| Frontline worker/student status | ||||||
| Student only | 689 | (17.4) | 348 | (17.6) | 341 | (17.3) |
| Frontline worker only | 2492 | (63.1) | 1225 | (62.0) | 1267 | (64.1) |
| Both student and frontline worker | 771 | (19.5) | 403 | (20.4) | 368 | (18.6) |
| Missing | 0 | (0.0) | 0 | (0.0) | 0 | (0.0) |
| Smoking | ||||||
| Everyday | 55 | (1.4) | 23 | (1.2) | 32 | (1.6) |
| Some days | 102 | (2.6) | 57 | (2.9) | 45 | (2.3) |
| Not at all | 3758 | (95.1) | 1877 | (95.0) | 1881 | (95.2) |
| Declined/missing | 37 | (0.9) | 19 | (1.0) | 18 | (0.9) |
| At least 1 medical conditiona | ||||||
| Yes | 213 | (5.4) | 111 | (5.6) | 102 | (5.2) |
| No | 3533 | (89.4) | 1799 | (91.0) | 1801 | (91.1) |
| Missing | 217 | (5.5) | 66 | (3.3) | 73 | (3.7) |
| At least 1 immunosuppressive conditionb | ||||||
| Yes | 45 | (1.1) | 24 | (1.2) | 21 | (1.1) |
| No | 3534 | (89.4) | 1757 | (88.9) | 1777 | (89.9) |
| Missing | 373 | (9.4) | 195 | (9.9) | 178 | (9.0) |
| No. of influenza vaccines received during last 5 seasons | ||||||
| 0 | 635 | (16.1) | 313 | (15.8) | 322 | (16.3) |
| 1 | 394 | (10.0) | 192 | (9.7) | 202 | (10.2) |
| 2 | 397 | (10.1) | 203 | (10.3) | 194 | (9.8) |
| 3 | 381 | (9.6) | 207 | (10.5) | 174 | (8.8) |
| 4 | 401 | (10.2) | 213 | (10.8) | 188 | (9.5) |
| 5 | 1639 | (41.5) | 799 | (40.4) | 840 | (42.5) |
| Unknown/missing | 105 | (2.7) | 49 | (2.5) | 56 | (2.8) |
| FLU-PRO total score at enrollment, mean (SD)c | 0.06 | (0.14) | 0.06 | (0.01) | 0.07 | (0.17) |
| Frequency of mask use while in close proximity of others at first surveillance contact | ||||||
| All of the time | 398 | (10.1) | 199 | (10.1) | 199 | (10.1) |
| Most of the time | 877 | (22.2) | 439 | (22.2) | 438 | (22.2) |
| Some of the time | 1276 | (32.3) | 645 | (32.6) | 631 | (31.9) |
| Never | 1266 | (32.0) | 635 | (32.1) | 631 | (31.9) |
| Missing | 135 | (3.4) | 58 | (2.9) | 77 | (3.9) |
| Characteristic . | All (n = 3952) . | SD IIV (n = 1976) . | RIV (n = 1976) . | |||
|---|---|---|---|---|---|---|
| No. . | (Column %) . | No. . | (Column %) . | No. . | (Column %) . | |
| Age, y | ||||||
| 18–49 | 3291 | (83.3) | 1646 | (83.3) | 1645 | (83.3) |
| 50–64 | 661 | (16.7) | 330 | (16.7) | 331 | (16.8) |
| Race | ||||||
| American Indian or Alaska Native | 29 | (0.7) | 15 | (0.8) | 14 | (0.7) |
| Asian | 782 | (19.8) | 392 | (19.8) | 390 | (19.7) |
| Black or African American | 460 | (11.6) | 228 | (11.5) | 232 | (11.7) |
| Native Hawaiian or Other Pacific Islander | 4 | (0.1) | 3 | (0.2) | 1 | (0.1) |
| White | 2348 | (59.4) | 1175 | (59.5) | 1173 | (59.4) |
| Multiracial | 148 | (3.7) | 75 | (3.8) | 73 | (3.7) |
| Declined/missing | 181 | (4.6) | 88 | (4.5) | 93 | (4.7) |
| Ethnicity | ||||||
| Hispanic or Latino/a | 600 | (15.2) | 299 | (15.1) | 301 | (15.2) |
| Not Hispanic or Latino/a | 3274 | (82.8) | 1641 | (83.1) | 1633 | (82.6) |
| Declined/missing | 78 | (2.0) | 36 | (1.8) | 42 | (2.1) |
| Gender | ||||||
| Female | 2476 | (62.7) | 1221 | (61.8) | 1255 | (63.5) |
| Male | 1406 | (35.6) | 722 | (36.5) | 684 | (34.6) |
| Transgender/other | 24 | (0.6) | 12 | (0.6) | 12 | (0.6) |
| None of these | 46 | (1.2) | 21 | (1.1) | 25 | (1.3) |
| Missing | 0 | (0.0) | 0 | (0.0) | 0 | (0.0) |
| Frontline worker/student status | ||||||
| Student only | 689 | (17.4) | 348 | (17.6) | 341 | (17.3) |
| Frontline worker only | 2492 | (63.1) | 1225 | (62.0) | 1267 | (64.1) |
| Both student and frontline worker | 771 | (19.5) | 403 | (20.4) | 368 | (18.6) |
| Missing | 0 | (0.0) | 0 | (0.0) | 0 | (0.0) |
| Smoking | ||||||
| Everyday | 55 | (1.4) | 23 | (1.2) | 32 | (1.6) |
| Some days | 102 | (2.6) | 57 | (2.9) | 45 | (2.3) |
| Not at all | 3758 | (95.1) | 1877 | (95.0) | 1881 | (95.2) |
| Declined/missing | 37 | (0.9) | 19 | (1.0) | 18 | (0.9) |
| At least 1 medical conditiona | ||||||
| Yes | 213 | (5.4) | 111 | (5.6) | 102 | (5.2) |
| No | 3533 | (89.4) | 1799 | (91.0) | 1801 | (91.1) |
| Missing | 217 | (5.5) | 66 | (3.3) | 73 | (3.7) |
| At least 1 immunosuppressive conditionb | ||||||
| Yes | 45 | (1.1) | 24 | (1.2) | 21 | (1.1) |
| No | 3534 | (89.4) | 1757 | (88.9) | 1777 | (89.9) |
| Missing | 373 | (9.4) | 195 | (9.9) | 178 | (9.0) |
| No. of influenza vaccines received during last 5 seasons | ||||||
| 0 | 635 | (16.1) | 313 | (15.8) | 322 | (16.3) |
| 1 | 394 | (10.0) | 192 | (9.7) | 202 | (10.2) |
| 2 | 397 | (10.1) | 203 | (10.3) | 194 | (9.8) |
| 3 | 381 | (9.6) | 207 | (10.5) | 174 | (8.8) |
| 4 | 401 | (10.2) | 213 | (10.8) | 188 | (9.5) |
| 5 | 1639 | (41.5) | 799 | (40.4) | 840 | (42.5) |
| Unknown/missing | 105 | (2.7) | 49 | (2.5) | 56 | (2.8) |
| FLU-PRO total score at enrollment, mean (SD)c | 0.06 | (0.14) | 0.06 | (0.01) | 0.07 | (0.17) |
| Frequency of mask use while in close proximity of others at first surveillance contact | ||||||
| All of the time | 398 | (10.1) | 199 | (10.1) | 199 | (10.1) |
| Most of the time | 877 | (22.2) | 439 | (22.2) | 438 | (22.2) |
| Some of the time | 1276 | (32.3) | 645 | (32.6) | 631 | (31.9) |
| Never | 1266 | (32.0) | 635 | (32.1) | 631 | (31.9) |
| Missing | 135 | (3.4) | 58 | (2.9) | 77 | (3.9) |
Abbreviations: FLU-PRO Plus, inFLUenza Patient-Reported Outcome Plus; RIV, recombinant influenza vaccine; SD IIV, standard-dose inactivated influenza vaccine.
aDiagnosed with or treated for at least 1 medical condition in the following categories during the past 12 months: autoimmune disorder, asthma, blood disorders, cancer, chronic lung disease, diabetes, heart conditions, high blood pressure, HIV/AIDS or other immunosuppressive condition, kidney disorder, liver disorder, metabolic disorder, neurological and neurodevelopmental conditions.
bImmunosuppressive conditions included cancer diagnosis or treatment in the past 12 months, receipt of immunosuppressive treatment or medication as a part of posttransplant treatment during the past 6 months, currently taking immunosuppressive medication, and diagnosis of HIV/AIDS irrespective of treatment status.
cThe FLU-PRO Plus is a patient-reported outcome tool that includes symptoms of respiratory tract infection across 8 body systems that has been previously validated for influenza and coronavirus disease 2019 [18, 19].
Baseline Characteristics of Trial Participants Overall and by Vaccine, Modified Intention-to-Treat Population, 2022–2023 Influenza Season (N = 3952)
| Characteristic . | All (n = 3952) . | SD IIV (n = 1976) . | RIV (n = 1976) . | |||
|---|---|---|---|---|---|---|
| No. . | (Column %) . | No. . | (Column %) . | No. . | (Column %) . | |
| Age, y | ||||||
| 18–49 | 3291 | (83.3) | 1646 | (83.3) | 1645 | (83.3) |
| 50–64 | 661 | (16.7) | 330 | (16.7) | 331 | (16.8) |
| Race | ||||||
| American Indian or Alaska Native | 29 | (0.7) | 15 | (0.8) | 14 | (0.7) |
| Asian | 782 | (19.8) | 392 | (19.8) | 390 | (19.7) |
| Black or African American | 460 | (11.6) | 228 | (11.5) | 232 | (11.7) |
| Native Hawaiian or Other Pacific Islander | 4 | (0.1) | 3 | (0.2) | 1 | (0.1) |
| White | 2348 | (59.4) | 1175 | (59.5) | 1173 | (59.4) |
| Multiracial | 148 | (3.7) | 75 | (3.8) | 73 | (3.7) |
| Declined/missing | 181 | (4.6) | 88 | (4.5) | 93 | (4.7) |
| Ethnicity | ||||||
| Hispanic or Latino/a | 600 | (15.2) | 299 | (15.1) | 301 | (15.2) |
| Not Hispanic or Latino/a | 3274 | (82.8) | 1641 | (83.1) | 1633 | (82.6) |
| Declined/missing | 78 | (2.0) | 36 | (1.8) | 42 | (2.1) |
| Gender | ||||||
| Female | 2476 | (62.7) | 1221 | (61.8) | 1255 | (63.5) |
| Male | 1406 | (35.6) | 722 | (36.5) | 684 | (34.6) |
| Transgender/other | 24 | (0.6) | 12 | (0.6) | 12 | (0.6) |
| None of these | 46 | (1.2) | 21 | (1.1) | 25 | (1.3) |
| Missing | 0 | (0.0) | 0 | (0.0) | 0 | (0.0) |
| Frontline worker/student status | ||||||
| Student only | 689 | (17.4) | 348 | (17.6) | 341 | (17.3) |
| Frontline worker only | 2492 | (63.1) | 1225 | (62.0) | 1267 | (64.1) |
| Both student and frontline worker | 771 | (19.5) | 403 | (20.4) | 368 | (18.6) |
| Missing | 0 | (0.0) | 0 | (0.0) | 0 | (0.0) |
| Smoking | ||||||
| Everyday | 55 | (1.4) | 23 | (1.2) | 32 | (1.6) |
| Some days | 102 | (2.6) | 57 | (2.9) | 45 | (2.3) |
| Not at all | 3758 | (95.1) | 1877 | (95.0) | 1881 | (95.2) |
| Declined/missing | 37 | (0.9) | 19 | (1.0) | 18 | (0.9) |
| At least 1 medical conditiona | ||||||
| Yes | 213 | (5.4) | 111 | (5.6) | 102 | (5.2) |
| No | 3533 | (89.4) | 1799 | (91.0) | 1801 | (91.1) |
| Missing | 217 | (5.5) | 66 | (3.3) | 73 | (3.7) |
| At least 1 immunosuppressive conditionb | ||||||
| Yes | 45 | (1.1) | 24 | (1.2) | 21 | (1.1) |
| No | 3534 | (89.4) | 1757 | (88.9) | 1777 | (89.9) |
| Missing | 373 | (9.4) | 195 | (9.9) | 178 | (9.0) |
| No. of influenza vaccines received during last 5 seasons | ||||||
| 0 | 635 | (16.1) | 313 | (15.8) | 322 | (16.3) |
| 1 | 394 | (10.0) | 192 | (9.7) | 202 | (10.2) |
| 2 | 397 | (10.1) | 203 | (10.3) | 194 | (9.8) |
| 3 | 381 | (9.6) | 207 | (10.5) | 174 | (8.8) |
| 4 | 401 | (10.2) | 213 | (10.8) | 188 | (9.5) |
| 5 | 1639 | (41.5) | 799 | (40.4) | 840 | (42.5) |
| Unknown/missing | 105 | (2.7) | 49 | (2.5) | 56 | (2.8) |
| FLU-PRO total score at enrollment, mean (SD)c | 0.06 | (0.14) | 0.06 | (0.01) | 0.07 | (0.17) |
| Frequency of mask use while in close proximity of others at first surveillance contact | ||||||
| All of the time | 398 | (10.1) | 199 | (10.1) | 199 | (10.1) |
| Most of the time | 877 | (22.2) | 439 | (22.2) | 438 | (22.2) |
| Some of the time | 1276 | (32.3) | 645 | (32.6) | 631 | (31.9) |
| Never | 1266 | (32.0) | 635 | (32.1) | 631 | (31.9) |
| Missing | 135 | (3.4) | 58 | (2.9) | 77 | (3.9) |
| Characteristic . | All (n = 3952) . | SD IIV (n = 1976) . | RIV (n = 1976) . | |||
|---|---|---|---|---|---|---|
| No. . | (Column %) . | No. . | (Column %) . | No. . | (Column %) . | |
| Age, y | ||||||
| 18–49 | 3291 | (83.3) | 1646 | (83.3) | 1645 | (83.3) |
| 50–64 | 661 | (16.7) | 330 | (16.7) | 331 | (16.8) |
| Race | ||||||
| American Indian or Alaska Native | 29 | (0.7) | 15 | (0.8) | 14 | (0.7) |
| Asian | 782 | (19.8) | 392 | (19.8) | 390 | (19.7) |
| Black or African American | 460 | (11.6) | 228 | (11.5) | 232 | (11.7) |
| Native Hawaiian or Other Pacific Islander | 4 | (0.1) | 3 | (0.2) | 1 | (0.1) |
| White | 2348 | (59.4) | 1175 | (59.5) | 1173 | (59.4) |
| Multiracial | 148 | (3.7) | 75 | (3.8) | 73 | (3.7) |
| Declined/missing | 181 | (4.6) | 88 | (4.5) | 93 | (4.7) |
| Ethnicity | ||||||
| Hispanic or Latino/a | 600 | (15.2) | 299 | (15.1) | 301 | (15.2) |
| Not Hispanic or Latino/a | 3274 | (82.8) | 1641 | (83.1) | 1633 | (82.6) |
| Declined/missing | 78 | (2.0) | 36 | (1.8) | 42 | (2.1) |
| Gender | ||||||
| Female | 2476 | (62.7) | 1221 | (61.8) | 1255 | (63.5) |
| Male | 1406 | (35.6) | 722 | (36.5) | 684 | (34.6) |
| Transgender/other | 24 | (0.6) | 12 | (0.6) | 12 | (0.6) |
| None of these | 46 | (1.2) | 21 | (1.1) | 25 | (1.3) |
| Missing | 0 | (0.0) | 0 | (0.0) | 0 | (0.0) |
| Frontline worker/student status | ||||||
| Student only | 689 | (17.4) | 348 | (17.6) | 341 | (17.3) |
| Frontline worker only | 2492 | (63.1) | 1225 | (62.0) | 1267 | (64.1) |
| Both student and frontline worker | 771 | (19.5) | 403 | (20.4) | 368 | (18.6) |
| Missing | 0 | (0.0) | 0 | (0.0) | 0 | (0.0) |
| Smoking | ||||||
| Everyday | 55 | (1.4) | 23 | (1.2) | 32 | (1.6) |
| Some days | 102 | (2.6) | 57 | (2.9) | 45 | (2.3) |
| Not at all | 3758 | (95.1) | 1877 | (95.0) | 1881 | (95.2) |
| Declined/missing | 37 | (0.9) | 19 | (1.0) | 18 | (0.9) |
| At least 1 medical conditiona | ||||||
| Yes | 213 | (5.4) | 111 | (5.6) | 102 | (5.2) |
| No | 3533 | (89.4) | 1799 | (91.0) | 1801 | (91.1) |
| Missing | 217 | (5.5) | 66 | (3.3) | 73 | (3.7) |
| At least 1 immunosuppressive conditionb | ||||||
| Yes | 45 | (1.1) | 24 | (1.2) | 21 | (1.1) |
| No | 3534 | (89.4) | 1757 | (88.9) | 1777 | (89.9) |
| Missing | 373 | (9.4) | 195 | (9.9) | 178 | (9.0) |
| No. of influenza vaccines received during last 5 seasons | ||||||
| 0 | 635 | (16.1) | 313 | (15.8) | 322 | (16.3) |
| 1 | 394 | (10.0) | 192 | (9.7) | 202 | (10.2) |
| 2 | 397 | (10.1) | 203 | (10.3) | 194 | (9.8) |
| 3 | 381 | (9.6) | 207 | (10.5) | 174 | (8.8) |
| 4 | 401 | (10.2) | 213 | (10.8) | 188 | (9.5) |
| 5 | 1639 | (41.5) | 799 | (40.4) | 840 | (42.5) |
| Unknown/missing | 105 | (2.7) | 49 | (2.5) | 56 | (2.8) |
| FLU-PRO total score at enrollment, mean (SD)c | 0.06 | (0.14) | 0.06 | (0.01) | 0.07 | (0.17) |
| Frequency of mask use while in close proximity of others at first surveillance contact | ||||||
| All of the time | 398 | (10.1) | 199 | (10.1) | 199 | (10.1) |
| Most of the time | 877 | (22.2) | 439 | (22.2) | 438 | (22.2) |
| Some of the time | 1276 | (32.3) | 645 | (32.6) | 631 | (31.9) |
| Never | 1266 | (32.0) | 635 | (32.1) | 631 | (31.9) |
| Missing | 135 | (3.4) | 58 | (2.9) | 77 | (3.9) |
Abbreviations: FLU-PRO Plus, inFLUenza Patient-Reported Outcome Plus; RIV, recombinant influenza vaccine; SD IIV, standard-dose inactivated influenza vaccine.
aDiagnosed with or treated for at least 1 medical condition in the following categories during the past 12 months: autoimmune disorder, asthma, blood disorders, cancer, chronic lung disease, diabetes, heart conditions, high blood pressure, HIV/AIDS or other immunosuppressive condition, kidney disorder, liver disorder, metabolic disorder, neurological and neurodevelopmental conditions.
bImmunosuppressive conditions included cancer diagnosis or treatment in the past 12 months, receipt of immunosuppressive treatment or medication as a part of posttransplant treatment during the past 6 months, currently taking immunosuppressive medication, and diagnosis of HIV/AIDS irrespective of treatment status.
cThe FLU-PRO Plus is a patient-reported outcome tool that includes symptoms of respiratory tract infection across 8 body systems that has been previously validated for influenza and coronavirus disease 2019 [18, 19].
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