TABLE 1. Number and percentage of children and adolescents aged 6 months–17 years receiving seasonal influenza vaccine, number and percentage with a positive or negative influenza test result, and vaccine effectiveness,* by influenza type† and subtype§ — three networks, United States, 2023–24 influenza season.
| Network (setting) | Influenza test result by influenza vaccination status, no. vaccinated/No. total (%) |
VE (95% CI)¶ | |
|---|---|---|---|
| Positive | Negative | ||
|
Any influenza
| |||
| NVSN** (outpatient††) |
123/622 (20) |
793/2,577 (31) |
59 (48–67) |
| US Flu VE (outpatient) |
29/283 (10) |
182/736 (25) |
67 (48–80) |
| VISION (outpatient) |
961/6,068 (16) |
4,579/15,274 (30) |
60 (57–64) |
| NVSN (inpatient) |
29/128 (23) |
543/1,321 (41) |
61 (40–75) |
| VISION (inpatient) |
21/113 (19) |
299/921 (32) |
52 (16–72) |
|
Any Influenza A
| |||
| NVSN (outpatient) |
84/411 (20) |
793/2,577 (31) |
55 (41–66) |
| US Flu VE (outpatient) |
27/212 (13) |
182/736 (25) |
46 (15–67) |
| VISION (outpatient) |
920/5,524 (17) |
4,579/15,274 (30) |
59 (55–62) |
| NVSN (inpatient) |
25/102 (25) |
543/1,321 (41) |
56 (30–73) |
| VISION (inpatient) |
21/105 (20) |
299/921 (32) |
46 (7–69) |
|
Influenza A(H1N1)pdm09
| |||
| NVSN (outpatient) |
61/298 (20) |
793/2,577 (31) |
54 (37–66) |
| US Flu VE (outpatient) |
11/120 (9) |
182/736 (25) |
61 (26–81) |
| NVSN (inpatient) |
18/79 (23) |
543/1,321 (41) |
60 (32–77) |
|
Influenza A(H3N2)
| |||
| NVSN (outpatient) |
19/87 (22) |
793/2,577 (31) |
55 (20–74) |
| US Flu VE (outpatient) |
2/17 (12) |
182/736 (25) |
— |
| NVSN (inpatient) |
4/10 (40) |
543/1,321 (41) |
— |
|
Influenza B
| |||
| NVSN (outpatient) |
39/216 (18) |
793/2,577 (31) |
64 (47–75) |
| US Flu VE (outpatient) |
3/76 (4) |
182/736 (25) |
89 (70–97) |
| VISION (outpatient) |
45/571 (8) |
4,579/15,274 (30) |
79 (71–85) |
| NVSN (inpatient) |
4/27 (15) |
543/1,321 (41) |
— |
| VISION (inpatient) | 0/10 (—) | 299/921 (32) | — |
Abbreviations: NVSN = New Vaccine Surveillance Network; OR = odds ratio; US Flu VE = U.S. 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 case-control design comparing vaccination odds among persons who had positive test results for influenza with vaccination odds among persons who had negative test results for any influenza and SARS-CoV-2. Calculated as (1 − adjusted OR) × 100%; ORs were estimated using logistic regression. Firth logistic regression was used for NVSN’s inpatient estimates.
† Influenza A and B coinfections were included in both influenza A and influenza B VE estimates.
§ Influenza A subtype estimates were not calculated for VISION because of limited subtype data.
¶ All networks adjusted for geographic region, age, and calendar time. US Flu VE and VISION adjusted for sex and race and ethnicity. US Flu VE also adjusted for time since illness onset and self-reported health status. VE estimates with fewer than 50 cases or from models that did not converge are not presented and are indicated with a dash.
** 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.
†† For NVSN and US Flu VE, outpatient setting is defined as outpatient clinics, urgent care, and emergency departments; for VISION, an outpatient setting is defined as urgent care and emergency departments.