Trial reportBMC infectious diseases2019
HAI and NAI titer correlates of inactivated and live attenuated influenza vaccine efficacy.
Trial report in BMC infectious diseases, 2019. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT00538512 (Comparative Study of Influenza Vaccines in Adults, FLUVACS-year 4), which is not on this map. Cited by 30 papers, 2 of them syntheses that pooled it.
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.
Comparative Study of Influenza Vaccines in Adults, FLUVACS-year 4
Who cites it
30 citing papers in PubMed, 2 syntheses or guidelines pooled it, 40 citations in OpenAlex.
- Human Immune Response to Influenza Neuraminidase After Vaccination: A Systematic Review.Influenza and other respiratory viruses · 2025Pooled it
- Effectiveness of interventions to improve vaccine efficacy: a systematic review and meta-analysis.Systematic reviews · 2025Pooled it
- Exogenous melatonin boosts vaccine-induced immunity in individuals with high pre-existing influenza immunity.Frontiers in immunology · 2025Trial
- Hemagglutination Inhibition Antibody Titers as Mediators of Influenza Vaccine Efficacy Against Symptomatic Influenza A(H1N1), A(H3N2), and B/Victoria Virus Infections.The Journal of infectious diseases · 2024Trial
- Trial
- T-cell-mediated immunity to influenza A (H2N3): implications for caccine efficacy and cross-subtype protection.Archives of microbiology · 2026Review
- Influenza Antibody Levels Associated with Laboratory-Confirmed Influenza in a Test-Negative Study Design, US Flu VE Network, November 2018-May 2019.medRxiv : the preprint server for health sciences · 2026Article
- The Road to Readiness: Commentary on the Journey of a Zoonotic H5 Influenza Vaccine Strain Update.Vaccines · 2026Review
- Review
- Vaccination against influenza viruses annually: Renewing or narrowing the protective shield?The Journal of experimental medicine · 2025Review
- Negative Control Outcome Adjustment in Early-Phase Randomized Trials: Estimating Vaccine Effects on Immune Responses in HIV Exposed Uninfected Infants.Statistics in medicine · 2025Article
- Article
- Expert consensus on the benefits of neuraminidase in conventional influenza vaccines: a Delphi study.BMC infectious diseases · 2025Article
- Review
- Review
- Article
- An atlas of continuous adaptive evolution in endemic human viruses.Cell host & microbe · 2023Article
- Interseason waning of vaccine-induced hemagglutination inhibition antibody titers and contributing factors to pre-existing humoral immunity against influenza in community-dwelling older adults 75 years and older.Immunity & ageing : I & A · 2023Article
- Research progress in methods for detecting neutralizing antibodies against SARS-CoV-2.Analytical biochemistry · 2023Review
- Association Between Hemagglutination Inhibition Antibody Titers and Protection Against Reverse-Transcription Polymerase Chain Reaction-Confirmed Influenza Illness in Children 6-35 Months of Age: Statistical Evaluation of a Correlate of Protection.Open forum infectious diseases · 2022Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
7 authors at 3 institutions in 1 country.
Funding
Abstract
backgroundHigh hemagglutination inhibition (HAI) and neuraminidase inhibition (NAI) titers are generally associated with reduced influenza risk. While repeated influenza vaccination reduces seroresponse, vaccine effectiveness is not always reduced.
methodsDuring the 2007-2008 influenza season, a randomized, placebo-controlled trial (FLUVACS) evaluated the efficacies of live-attenuated (LAIV) and inactivated influenza vaccines (IIV) among healthy adults aged 18-49 in Michigan; IIV vaccine efficacy (VE) and LAIV VE against influenza disease were estimated at 68% and 36%. Using the principal stratification/VE moderation framework, we analyzed data from this trial to assess how each VE varied by HAI or NAI responses to vaccination observed for vaccinated individuals and predicted counterfactually for placebo recipients. We also assessed how each VE varied with pre-vaccination/baseline variables including HAI titer, NAI titer, and vaccination history.
resultsIIV VE appeared to increase with Day 30 post-vaccination HAI titer, albeit not significantly (p=0.20 and estimated VE 14.4%, 70.5%, and 85.5% at titer below the assay lower quantification limit, 512, and 4096 (maximum)). Moreover, IIV VE increased significantly with Day 30 post-vaccination NAI titer (p=0.040), with estimated VE zero at titer 10 and 92.2% at highest titer 640. There was no evidence that fold-change in post-vaccination HAI or NAI titer associated with IIV VE (p=0.76, 0.38). For LAIV, there was no evidence that VE associated with post-vaccination or fold-rise HAI or NAI titers (p-values >0.40). For IIV, VE increased with increasing baseline NAI titer in those previously vaccinated, but VE decreased with increasing baseline NAI titer in those previously unvaccinated. In contrast, for LAIV, VE did not depend on previous vaccination or baseline HAI or NAI titer.
conclusionsFuture efficacy trials should measure baseline and post-vaccination antibody titers in both vaccine and control/placebo recipients, enabling analyses to better elucidate correlates of vaccine- and natural-protection.
trial registrationClinicalTrials.gov NCT00538512. October 1, 2007.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.