At a glance
Inclusion Dates by Network
Network
Dates
September 20, 2025–February 6, 2026
September 28, 2025–January 23, 2026
October 1, 2025–January 23, 2026
Flu Vaccine Effectiveness for Children and Adults
Influenza vaccine effectiveness* against outpatient encounters and hospitalization among children and adolescents† and adults who received a seasonal influenza vaccine by age group, case status, percentage of persons vaccinated, influenza test result, and influenza type and subtype§ — Three surveillance networks, United States, 2025–26 influenza season
| Network (Setting¶) | Influenza positive N vaccinated / Total (%) |
Influenza negative N vaccinated / Total (%) |
VE (95% CI)** |
|---|---|---|---|
| All age groups | |||
| Any†† influenza | |||
| US Flu VE (outpatient) | 214/731 (29) | 949/2,649 (36) | 24 (8 to 38) |
| VISION (outpatient) | 4,943/21,801 (23) | 27,338/86,738 (32) | 36 (33 to 39) |
| VISION (inpatient) | 735/2,038 (36) | 9,779/24,845 (39) | 31 (23 to 39) |
| All children and adolescents aged 6 months–17 yrs† | |||
| Any†† influenza | |||
| NVSN§§ (outpatient) | 149/729 (20) | 485/1,567 (31) | 41 (25 to 53) |
| US Flu VE (outpatient) | 74/289 (26) | 193/780 (25) | 14 (−20 to 39) |
| VISION (outpatient) | 1,432/8,253 (17) | 4,958/22,979 (22) | 38 (33 to 43) |
| NVSN (inpatient) | 81/248 (33) | 490/1,148 (43) | 41 (20 to 56) |
| VISION (inpatient) | 19/93 (20) | 339/1,179 (29) | 48 (−12 to 78) |
| Influenza A | |||
| NVSN (outpatient) | 141/652 (22) | 485/1,567 (31) | 37 (20 to 50) |
| US Flu VE (outpatient) | 53/194 (27) | 193/780 (25) | 10 (−32 to 39) |
| VISION (outpatient) | 1,394/7,992 (17) | 4,958/22,979 (22) | 38 (33 to 43) |
| NVSN (inpatient) | 75/230 (33) | 490/1,148 (43) | 42 (21 to 57) |
| VISION (inpatient) | 19/93 (20) | 339/1,179 (29) | 48 (−12 to 78) |
| Influenza A(H3N2) | |||
| NVSN (outpatient) | 132/598 (22) | 485/1,567 (31) | 35 (17 to 49) |
| US Flu VE (outpatient) | 43/147 (29) | 193/780 (25) | 2 (−49 to 37) |
| NVSN (inpatient) | 63/187 (34) | 490/1,148 (43) | 38 (13 to 55) |
| Influenza B | |||
| NVSN (outpatient) | 8/80 (10) | 485/1,567 (31) | 71 (41 to 86) |
| US Flu VE (outpatient) | 21/95 (22) | 193/780 (25) | 20 (−41 to 56) |
| VISION (outpatient) | 39/272 (14) | 4,958/22,979 (22) | 45 (22 to 62) |
| NVSN (inpatient) | 7/19 (37) | 490/1,148 (43) | NR¶¶ |
| VISION (inpatient) | *** | 339/1,179 (29) | NR¶¶ |
| All adults aged ≥18 yrs | |||
| Any influenza | |||
| US Flu VE†† (outpatient) | 140/442 (32) | 756/1,869 (40) | 22 (1 to 39) |
| VISION (outpatient) | 3,511/13,548 (26) | 22,380/63,759 (35) | 34 (31 to 38) |
| VISION (inpatient) | 716/1,945 (37) | 9,440/23,666 (40) | 30 (21 to 38) |
| Influenza A | |||
| US Flu VE (outpatient) | 123/381 (32) | 756/1,869 (40) | 21 (−2 to 39) |
| VISION (outpatient) | 3,479/13,308 (26) | 22,380/63,759 (35) | 34 (30 to 37) |
| VISION (inpatient) | 712/1,927 (37) | 9,440/23,666 (40) | 30 (21 to 38) |
| Influenza A(H3N2) | |||
| US Flu VE (outpatient) | 103/295 (35) | 756/1,869 (40) | 11 (−18 to 33) |
| Influenza B | |||
| US Flu VE (outpatient) | 17/61 (28) | 756/1,869 (40) | 23 (−40 to 59) |
| VISION (outpatient) | 36/250 (14) | 22,380/63,759 (35) | 63 (48 to 75) |
| VISION (inpatient) | *** | 9,440/23,666 (40) | NR¶¶ |
| All adults aged 18–64 yrs | |||
| Any influenza | |||
| US Flu VE (outpatient) | 89/358 (25) | 455/1,426 (32) | 24 (−1 to 42) |
| VISION (outpatient) | 1,778/9,973 (18) | 8,832/38,454 (23) | 36 (31 to 40) |
| VISION (inpatient) | 135/639 (21) | 1,710/7,026 (24) | 29 (11 to 45) |
| Influenza A | |||
| US Flu VE (outpatient) | 74/301 (25) | 455/1,426 (32) | 23 (−4 to 43) |
| VISION (outpatient) | 1,756/9,759 (18) | 8,832/38,454 (23) | 35 (30 to 39) |
| VISION (inpatient) | 134/627 (21) | 1,710/7,026 (24) | 28 (8 to 43) |
| Influenza A(H3N2) | |||
| US Flu VE (outpatient) | 64/232 (28) | 455/1,426 (32) | 12 (−22 to 37) |
| Influenza B | |||
| US Flu VE (outpatient) | 15/57 (26) | 455/1,426 (32) | NR††† |
| VISION (outpatient) | 24/220 (11) | 8,832/38,454 (23) | 66 (50 to 78) |
| VISION (inpatient) | *** | 1,710/7,026 (24) | NR¶¶ |
| All adults aged ≥65 yrs | |||
| Any influenza | |||
| US Flu VE (outpatient) | 51/84 (61) | 301/443 (68) | 41 (1 to 64) |
| VISION (outpatient) | 1,733/3,575 (48) | 13,548/25,305 (54) | 30 (24 to 36) |
| VISION (inpatient) | 581/1,306 (44) | 7,730/16,640 (46) | 31 (21 to 39) |
| Influenza A | |||
| US Flu VE (outpatient) | 49/80 (61) | 301/443 (68) | 40 (−2 to 64) |
| VISION (outpatient) | 1,723/3,549 (49) | 13,548/25,305 (54) | 30 (24 to 36) |
| VISION (inpatient) | 578/1,300 (44) | 7,730/16,640 (46) | 31 (20 to 40) |
| Influenza A(H3N2) | |||
| US Flu VE (outpatient) | 39/63 (62) | 301/443 (68) | 37 (−14 to 65) |
| Influenza B | |||
| US Flu VE (outpatient) | 2/4 (50) | 301/443 (68) | NR¶¶ |
| VISION (outpatient) | 12/30 (40) | 13,548/25,305 (54) | NR¶¶ |
| VISION (inpatient) | *** | 7,730/16,640 (46) | NR¶¶ |
Abbreviations: CI = confidence interval; NR = not reported; NVSN = New Vaccine Surveillance Network; OR = odds ratio; US Flu VE = US Flu Vaccine Effectiveness Network; VE = Vaccine Effectiveness; VISION = Virtual SARS-CoV-2, Influenza, and Other respiratory viruses Network.
*VE was estimated using the test-negative design comparing odds of receipt of 2025–26 influenza vaccination among persons with an acute respiratory illness who received a negative influenza or SARS-CoV-2 test result. Adjusted ORs were estimated using logistic regression; VE was calculated as (1–adjusted OR) x 100, expressed as a %. Firth logistic regression was used for estimates from NVSN.
†Age = 6 months–17 yrs (NVSN and VISION); 8 months–17 yrs (US Flu VE). All estimates were adjusted for geographic region, age, and calendar time. VISION also adjusted for sex and race and ethnicity.
§Influenza A-subtype was not available for VISION.
¶Outpatient = outpatient clinics, urgent care, primary care, and emergency departments (NVSN and US Flu VE); or urgent care and emergency departments (VISION).
**CIs that exclude 0 are considered to be statistically significant.
††As of February 7, 2026, most influenza viruses detected have been influenza A viruses (90% of positive specimens).
§§Patients enrolled as outpatients in NVSN might have progressed to a more acute level of care, and those data might not be reflected in this analysis.
¶¶Estimates were not reported if there were fewer than 50 cases.
***For VISION, cells with counts <5 were suppressed.
†††Estimates were not reported if VE CI width ≥100.