Flu Vaccine Effectiveness (VE) Data for 2022-2023

CDC References (severe flu outcomes): NVSN (preliminary): February 2023 ACIP Presentation [4.5 MB, 25 pages]; VISION: Adams, et al., 2024; Tenforde, et al., 2023; IVY: Lewis, et al., 2023

External Reference (medically attended flu illness): Marshfield, WI (preliminary): McLean, et al., 2023

Inclusion Dates by Network

Flu Vaccine Effectiveness for Children

*VE was estimated using the test-negative design comparing vaccination odds among persons who tested positive for influenza to vaccination odds among persons who tested negative for any influenza and SARS-CoV-2. Calculated as (1 − adjusted OR ) × 100%; ORs were estimated using logistic regression.

^†Subtype was not available for VISION.

^¶All networks adjusted for geographic region, age, calendar time. VISION adjusted for sex and race/ethnicity. VE estimates with fewer than 50 cases or from models that did not converge are not presented and are represented with a “—”

^††Outpatient is defined as emergency departments for NVSN. Outpatient is defined as urgent care and emergency departments for VISION.

***NVSN data are preliminary.

Flu Vaccine Effectiveness for Adults

*VE was estimated using the test-negative design comparing vaccination odds among persons who tested positive for influenza to vaccination odds among persons who tested negative for any influenza and SARS-CoV-2. Calculated as (1 − adjusted OR) × 100%; ORs were estimated using logistic regression.

^†Subtype was not available for VISION.

^¶All networks adjusted for geographic region, age, calendar time. IVY and VISION, adjusted for sex and race/ethnicity. VE estimates with fewer than 50 cases or from models that did not converge are not presented and are represented with a “—”

**Outpatient is defined as urgent care and emergency departments for VISION.

¹ Includes active solid-organ cancer, active hematologic cancer, solid-organ transplant, bone marrow/stem cell transplant, HIV infection, congenital immunodeficiency syndrome, use of an immunosuppressive medication within the last 30 days, splenectomy, graft-versus-host disease (currently or in the past), or any other condition that causes moderate or severe immunosuppression.

²Defined as at least one discharge diagnosis for solid malignancy, hematologic malignancy, rheumatologic or inflammatory disorder, other intrinsic immune condition or immunodeficiency, or organ or stem cell transplant.