# Comparison of High vs. Standard Dose Influenza Vaccines in Adult Solid Organ Transplant Recipients

> **NIH NIH U01** · VANDERBILT UNIVERSITY MEDICAL CENTER · 2021 · $838,428

## Abstract

PROJECT SUMMARY
Influenza virus is a significant pathogen in adult solid organ transplant (SOT) recipients. However, these
individuals respond poorly to standard-dose (SD) inactivated influenza vaccine (IIV). Recent studies have
investigated two strategies to overcome poor immune responses in SOT recipients: (1) administration of high-
dose (HD)-IIV compared to SD-IIV and (2) two doses of SD-IIV compared to one dose of SD-IIV in the same
influenza season. The first study compared HD-IIV vs.SD-IIV in adult SOT recipients and noted that HD-IIV
was safe and reported higher immunogenicity; however, the median post-transplant period was 38 months. In
another phase II trial of adult SOT recipients, two doses of SD-IIV a month apart compared to one-dose of SD-
IIV revealed increased immunogenicity, with a median post-transplant period of 18 months. Therefore, these
studies lack evaluation in the early post-transplant period in this vulnerable population. Additionally, the
administration of two-doses of HD-IIV in the same influenza season has not been evaluated in SOT recipients.
Thus, the optimal immunization strategy for SOT recipients less than 12 months post-transplant is unknown. In
addition, the immunologic predictors and correlates of influenza vaccine immunogenicity in SOT recipients
have not been well-defined. The central hypothesis of our proposal is that adult SOT recipients that are
1-11 months out from transplant and are receiving two doses of HD-IIV will have higher
hemagglutination inhibition geometric mean titers (GMT) to influenza A antigens compared to adult
SOT recipients receiving two doses of SD-IIV over one influenza season. To test this hypothesis and
address the critical knowledge gaps outlined above, we propose to conduct a phase II, multi-center,
randomized-controlled immunogenicity and safety trial comparing either one dose of HD-IIV, two doses of SD-
IIV, or two doses of HD-IIV in adult kidney, heart, and/or liver SOT recipients 1-11 months post-transplant. The
results of this study will address significant knowledge gaps regarding influenza vaccine strategies and
immune responses in adult SOT recipients and will guide vaccine recommendations in the early post-
transplant period.

## Key facts

- **NIH application ID:** 10246980
- **Project number:** 5U01AI152967-02
- **Recipient organization:** VANDERBILT UNIVERSITY MEDICAL CENTER
- **Principal Investigator:** NATASHA Bassam HALASA
- **Activity code:** U01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $838,428
- **Award type:** 5
- **Project period:** 2020-09-01 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10246980

## Citation

> US National Institutes of Health, RePORTER application 10246980, Comparison of High vs. Standard Dose Influenza Vaccines in Adult Solid Organ Transplant Recipients (5U01AI152967-02). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10246980. Licensed CC0.

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