Talk to the Veterans Crisis Line now
U.S. flag
An official website of the United States government

VA Health Systems Research

Go to the VA ORD website
Go to the QUERI website

HSR Citation Abstract

Search | Search by Center | Search by Source | Keywords in Title

Effectiveness of the 2023-to-2024 XBB.1.5 COVID-19 Vaccines Over Long-Term Follow-up : A Target Trial Emulation.

Ioannou GN, Berry K, Rajeevan N, Li Y, Yan L, Huang Y, Lin HM, Bui D, Hynes DM, Rowneki M, Bohnert A, Boyko EJ, Iwashyna TJ, Maciejewski ML, Smith VA, Berkowitz TSZ, O'Hare AM, Viglianti EM, Aslan M, Bajema KL. Effectiveness of the 2023-to-2024 XBB.1.5 COVID-19 Vaccines Over Long-Term Follow-up : A Target Trial Emulation. Annals of internal medicine. 2025 Feb 4.

Dimensions for VA is a web-based tool available to VA staff that enables detailed searches of published research and research projects.

If you have VA-Intranet access, click here for more information vaww.hsrd.research.va.gov/dimensions/

VA staff not currently on the VA network can access Dimensions by registering for an account using their VA email address.
   Search Dimensions for VA for this citation
* Don't have VA-internal network access or a VA email address? Try searching the free-to-the-public version of Dimensions



Abstract:

BACKGROUND: Monovalent COVID-19 vaccines targeting the XBB.1.5 Omicron variant were introduced in September 2023. In the absence of randomized controlled trials demonstrating their efficacy, information on real-world vaccine effectiveness (VE) is needed. OBJECTIVE: To determine XBB.1.5 COVID-19 VE and the extent to which it declines over time. DESIGN: Target trial emulation. SETTING: U.S. Veterans Health Administration. PARTICIPANTS: Eligible XBB.1.5 vaccine recipients were matched 1:1 to unvaccinated persons in 7 sequential biweekly trials with enrollment from 2 October 2023 through 3 January 2024. INTERVENTION: XBB.1.5 COVID-19 vaccination versus no XBB.1.5 vaccination. MEASUREMENTS: Outcomes were ascertained through 10 May 2024 and included any positive result on a SARS-CoV-2 test from day 10 after the matched index date, subsequent hospitalization within 1 day before or 10 days after the positive result, or death within 30 days after the positive result. Vaccine effectiveness was estimated as 100?×?(1?-?risk ratio). RESULTS: Participants (91.3% male; mean age, 69.9 years) included 587?137 pairs of vaccinated and matched unvaccinated persons. Over a mean follow-up of 176 days (range, 118 to 211 days), VE was -3.26% (95% CI, -6.78% to -0.22%) against documented SARS-CoV-2 infection, 16.64% (CI, 6.47% to 25.77%) against SARS-CoV-2-associated hospitalization, and 26.61% (CI, 5.53% to 42.32%) against SARS-CoV-2-associated death. When estimated at 60, 90, and 120 days, respectively, VE against documented infection (14.21%, 7.29%, and 3.15%), hospitalization (37.57%, 30.84%, and 25.25%), or death (54.24%, 44.33%, and 30.25%) showed substantial waning. LIMITATION: Potential for residual confounding and incomplete capture of COVID-19 vaccination and SARS-CoV-2-related outcomes. CONCLUSION: COVID-19 vaccines targeting the XBB.1.5 variant of Omicron were not effective in preventing infection and had relatively low VE against hospitalization and death, which declined rapidly over time. PRIMARY FUNDING SOURCE: U.S. Department of Veterans Affairs.





Questions about the HSR website? Email the Web Team

Any health information on this website is strictly for informational purposes and is not intended as medical advice. It should not be used to diagnose or treat any condition.