Trial reportVaccine2024
Safety and immunogenicity of locally produced trivalent inactivated influenza vaccine (Tri Fluvac) in healthy Thai adults aged 18-64 years in Nakhon Phanom: A Phase III double blinded, three-arm, randomized, controlled trial.
Trial report in Vaccine, 2024. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
1 citing paper in PubMed, 0 citations in OpenAlex.
- Effectiveness of a trivalent inactivated split-virion influenza vaccine (Tri Fluvac) in Thailand: a phase IV test-negative case-control study.The Lancet regional health. Southeast Asia · 2026Article
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Authors and funding
19 authors at 6 institutions in 3 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundDomestic influenza vaccine production facilitates a sustainable supply for mitigating seasonal influenza and improves national health security by providing infrastructure and experience for pandemic vaccine production, if needed.
methodsA Phase III, double blind, randomized controlled trial was conducted from Sep 2019-Oct 2020 in healthy adults 18-64 years in Nakhon Phanom, Thailand. Randomization (3:3:1) compared study vaccine (Tri Fluvac), saline placebo, and an active comparator (licensed vaccine). Primary outcomes were superior efficacy compared to placebo based on RT-PCR-confirmed influenza virus infection within 12 months and non-inferiority compared to active comparator based on immunogenicity (HAI assay) at 28 days. Safety was also assessed.
resultsThe trial enrolled 4,284 participants (Tri Fluvac = 1,836; placebo = 1,836; active comparator = 612). There were 29 RT-PCR positive influenza infections (10 Tri Fluvac, 5.5/1,000 PY; 19 placebo, 10.4/1,000PY; 0 comparator) for an absolute protective efficacy of 46.4 (95 % CI = -22.0-76.5) compared with placebo, but the power was 43.7 %. Seroconversion difference rates between Tri Fluvac and comparator at Day 28 were 1.74 (95 % CI: -2.77, 6.25), 2.22 (-2.40, 6.84), and -0.57 (-5.41, 4.27) for A(H1N1), A(H3N2), and B strains, respectively. Adverse and severe adverse events occurred in 175 (9.5 %) Tri Fluvac, 177 (10.8 %) placebo, and 66 (10.8 %) comparator arms (p-value = 0.437, Tri Fluvac vs. comparator)
conclusionsTri Fluvac was well tolerated, and immunogenicity was non-inferior to the active comparator, meeting U.S. Food and Drug Administration (FDA) criteria for adult vaccine licensure. Few acute respiratory infections were reported during intense COVID-19 pandemic restrictions, resulting in insufficient power to evaluate clinical efficacy.
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