scholarly journals Frailty Is Associated With Increased Hemagglutination-Inhibition Titers in a 4-Year Randomized Trial Comparing Standard- and High-Dose Influenza Vaccination

2020 ◽  
Vol 7 (5) ◽  
Author(s):  
Nathalie Loeb ◽  
Melissa K Andrew ◽  
Mark Loeb ◽  
George A Kuchel ◽  
Laura Haynes ◽  
...  
Keyword(s):  
Influenza Vaccination ◽  
Hemagglutination Inhibition ◽  
Influenza A ◽  
Standard Dose ◽  
Geometric Mean ◽  
Frailty Index ◽  
Antibody Responses ◽  
High Dose ◽  
Antibody Titers ◽  
The Impact

Abstract Background Although high-dose (HD) vaccines have been reported to stimulate higher antibody responses compared with standard-dose (SD) influenza vaccines, there have been limited studies on the impact of frailty on such responses. Methods We conducted a randomized, double-blind trial (2014/2015 to 2017/2018) of SD versus HD trivalent split-virus vaccine (Fluzone) in 612 study participants aged 65+ over 4 influenza seasons. Hemagglutination inhibition antibody titers for influenza H1N1, H3N2, and B vaccine subtypes were measured at baseline and at 4, 10, and 20 weeks postvaccination and frailty was measured using a validated frailty index. Results Geometric mean antibody titers were significantly higher in HD compared with SD vaccine recipients for all influenza subtypes at all time points postvaccination. However, frailty was positively correlated with 4-week titers and was associated with increased odds of being a vaccine responder. For influenza A subtypes, this was mostly limited to HD recipients. Conclusions Frailty was associated with higher titers and increased antibody responses at 4 weeks after influenza vaccination, which was partially dependent on vaccine dosage. Chronic inflammation or dysregulated immunity, both of which are commonly observed with frailty, may be responsible, but it requires further investigation.

Potential for Single High-Dose Influenza Immunization in Unprimed Children

PEDIATRICS ◽  
1982 ◽  
Vol 70 (6) ◽  
pp. 982-986 ◽  
Author(s):  
Peter A. Gross ◽  
Gerald V. Quinnan ◽  
Pureza F. Gaerlan ◽  
Carolyn R. Denning ◽  
Anne Davis ◽  
...  
Keyword(s):  
New York ◽  
Influenza A ◽  
Standard Dose ◽  
Geometric Mean ◽  
High Dose ◽  
York Metropolitan Area ◽  
Reaction Index ◽  
Number Of Patients ◽  
Sibling Control ◽  
High Concentrations

High concentrations of split-product vaccine (SPV) are more immunogenic than lower concentrations. These studies were verified with another influenza strain, B/Singapore/22/79. Two ether-treated SPVs were compared in 80 children and young adults. The vaccine strains were influenza A/Bangkok/79, A/Brazil/78, and B/Singapore /79; 44 patients received a high-dose SPV containing 7, 7, and 60 µg each of the respective hemagglutinins (HA) and 36 received a standard dose SPV containing 7, 7, and 7 µg of HA, respectively. Among persons initially seronegative by hemagglutination inhibition (HAI) tests, the geometric mean titer (GMT) in 15 recipients of one high dose was 97 vs GMT of 37 in 18 recipients of one standard dose (P < .05). Furthermore, 87% of high-dose recipients had HAI titer ≥ 40 vs 44% of standard dose recipients. In initially seropositive persons, GMT in 29 recipients of one high dose was 170 vs GMT of 84 in 18 recipients of one standard dose (P < .05). Immune response to the other two virus strains was comparable for the two vaccines. The reaction index for the high dose vaccine was 0.70 vs 0.45 for the standard dose (P = NS). An A/Bangkok epidemic struck the New York metropolitan area. The attack rate in unvaccinated matched sibling control subjects was 35% (15/43). There were no vaccine failures. In conclusion, in the small number of patients studied, a 60-µg HA dose of B/Singapore/79 was significantly more immunogenic than a standard 7-µg HA dose without an increase in reactogenicity.

The Effect of Influenza Vaccination History on Changes in Hemagglutination Inhibition Titers After Receipt of the 2015–2016 Influenza Vaccine in Older Adults in Hong Kong

2019 ◽  
Vol 221 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Tiffany W Y Ng ◽  
Ranawaka A P M Perera ◽  
Vicky J Fang ◽  
Emily M Yau ◽  
J S Malik Peiris ◽  
...  
Keyword(s):  
Older Adults ◽  
Hong Kong ◽  
Influenza Vaccine ◽  
Influenza Vaccination ◽  
Hemagglutination Inhibition ◽  
Age Groups ◽  
Antibody Responses ◽  
Serum Samples ◽  
Vaccination History ◽  
Antibody Titers

Abstract Background Immune responses to influenza vaccination can be weaker in older adults than in other age groups. We hypothesized that antibody responses would be particularly weak among repeat vaccinees when the current and prior season vaccine components are the same. Methods An observational study was conducted among 827 older adults (aged ≥75 years) in Hong Kong. Serum samples were collected immediately before and 1 month after receipt of the 2015–2016 quadrivalent inactivated influenza vaccine. We measured antibody titers with the hemagglutination inhibition assay and compared the mean fold rise from prevaccination to postvaccination titers and the proportions with postvaccination titers ≥40 or ≥160. Results Participants who reported receipt of vaccination during either of the previous 2 years had a lower mean fold rise against all strains than with those who did not. Mean fold rises for A(H3N2) and B/Yamagata were particularly weak after repeated vaccination with the same vaccine strain, but we did not generally find significant differences in the proportions of participants with postvaccination titers ≥40 and ≥160. Conclusions Overall, we found that reduced antibody responses in repeat vaccinees were particularly reduced among older adults who had received vaccination against the same strains in preceding years.

scholarly journals Key Determinants of Cell-Mediated Immune Responses: A Randomized Trial of High Dose Vs. Standard Dose Split-Virus Influenza Vaccine in Older Adults

2021 ◽  
Vol 2 ◽  
Author(s):  
Chris P. Verschoor ◽  
Laura Haynes ◽  
Graham Pawelec ◽  
Mark Loeb ◽  
Melissa K. Andrew ◽  
...  
Keyword(s):  
Older Adults ◽  
Immune Responses ◽  
Influenza Vaccine ◽  
Influenza A ◽  
Standard Dose ◽  
Serum Antibody ◽  
High Dose ◽  
Post Vaccination ◽  
Antibody Titers ◽  
Virus Influenza

Background: Efforts to improve influenza vaccine effectiveness in older adults have resulted in some successes, such as the introduction of high-dose split-virus influenza vaccine (HD-SVV), yet studies of cell-mediated immune responses to these vaccines remain limited. We have shown that granzyme B (GrB) activity in influenza A/H3N2 challenged peripheral blood mononuclear cells (PBMC) correlates with protection against influenza following standard dose vaccination (SD-SVV) in older adults. Further, the interferon-γ (IFNγ) to interleukin-10 (IL-10) ratio can be a correlate of protection.Methods: In a double-blind trial (ClinicalTrials.gov NCT02297542) older adults (≥65 years, n = 582) were randomized to receive SD-SVV or HD-SVV (Fluzone®) from 2014/15 to 2017/18. Young adults (20–40 years, n = 79) received SD-SVV. At 0, 4, 10, and 20 weeks post-vaccination, serum antibody titers, IFNγ, IL-10, and inducible GrB (iGrB) were measured in ex vivo influenza-challenged PBMC. iGrB is defined as the fold change in GrB activity from baseline levels (bGrB) in circulating T cells. Responses of older adults were compared to younger controls, and in older adults, we analyzed effects of age, sex, cytomegalovirus (CMV) serostatus, frailty, and vaccine dose.Results: Prior to vaccination, younger compared to older adults produced significantly higher IFNγ, IL-10, and iGrB levels. Relative to SD-SVV recipients, older HD-SVV recipients exhibited significantly lower IFNγ:IL-10 ratios at 4 weeks post-vaccination. In contrast, IFNγ and iGrB levels were higher in younger SD vs. older SD or HD recipients; only the HD group showed a significant IFNγ response to vaccination compared to the SD groups; all three groups showed a significant iGrB response to vaccination. In a regression analysis, frailty was associated with lower IFNγ levels, whereas female sex and HD-SVV with higher IL-10 levels. Age and SD-SVV were associated with lower iGrB levels. The effect of prior season influenza vaccination was decreased iGrB levels, and increased IFNγ and IL-10 levels, which correlated with influenza A/H3N2 hemagglutination inhibition antibody titers.Conclusion: Overall, HD-SVV amplified the IL-10 response consistent with enhanced antibody responses, with little effect on the iGrB response relative to SD-SVV in either younger or older adults. These results suggest that enhanced protection with HD-SVV is largely antibody-mediated.Clinical Trial Registration: ClinicalTrials.gov (NCT02297542).

scholarly journals 2737. Comparison of Antibody Responses to Vaccination with a Pure Hemagglutinin Influenza Vaccine (rHA) and Licensed Subvirion Influenza Vaccine Made in Eggs or Cell Culture in Adults 60 Years and Older

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S963-S963
Author(s):  
Moumita Sarker ◽  
Angela Branche ◽  
Michael Peasley ◽  
David Topham
Keyword(s):  
Older Adults ◽  
Influenza Vaccine ◽  
Vaccine Development ◽  
Standard Dose ◽  
Geometric Mean ◽  
The United States ◽  
Antibody Responses ◽  
Influenza B Virus ◽  
Influenza B ◽  
High Dose

Abstract Background Influenza is associated with increased mortality and morbidity for older adults. High-dose egg grown trivalent inactivated influenza vaccine (Fluzone HD) is safe and provides superior immune responses in older adults compared with standard dose (SD). Recently, two new vaccines have been licensed in the United States: cell cultured inactivated vaccine FluCelVax and baculovirus-expressed pure hemagglutinin (HA) vaccine FluBlok. Data from one study demonstrated higher efficacy with FluBlok than SD Fluzone in older adults. There is no data however comparing HD Fluzone to FluBlok and FluCelVax has not been studied at all. The purpose of this study was to assess hemagglutinin inhibition (HAI) antibody responses to vaccination with three vaccines in adults ≥ 60 years. Methods Adults ≥ 60 years were randomly assigned to receive one of the three vaccines: Fluzone HD, FluBlok and FluCelVax (Figure 1). Active influenza-like illness (ILI) surveillance was conducted with bi-weekly telephone calls. Serum samples were collected prior to vaccination and at day 7, 14, 28 and 180 and antibody responses assessed by HAI titer to A/Singapore/INFIMH-16–0019(H3N2), A/Michigan/45/2015(H1N1) and B/Colorado/6/2017 (Victoria) viruses as well as a circulating H3N2 strain. The primary endpoint was a 4-fold rise in antibody titer at day 28. Results 48 subjects were vaccinated in October 2018. Mean age was 69 and 65% were female. Two subjects reported ILI symptoms and one was positive for infection (H1N1). A majority of subjects demonstrated pre-existing antibody to all three viruses (Figure 2, Blue). Geometric mean titers (GMT) for antibody responses to the influenza A viruses were similar for FluBlok (FB) and HD Fluzone (FZ) but lower for FluCelVax(FCB) subjects (Figure 2, Orange). A higher percent of FlubBlok subjects demonstrated 4-fold rise in antibody responses to the Victoria influenza B virus (FB GMT 140 vs. FZ GMT 116, P = 0.26). Conclusion In this small study, antibody responses were similar or higher in older adults after vaccination with FluBlok compared with Fluzone HD with lower responses demonstrated with FluCelvax. Emerging concerns about HA egg adaptation during vaccine development compels further study to determine the appropriate vaccination strategy for this vulnerable population. Disclosures All authors: No reported disclosures.

scholarly journals Induction of Cross-Reactive Hemagglutination Inhibiting Antibody and Polyfunctional CD4+ T-Cell Responses by a Recombinant Matrix-M–Adjuvanted Hemagglutinin Nanoparticle Influenza Vaccine

2020 ◽  
Author(s):  
Vivek Shinde ◽  
Rongman Cai ◽  
Joyce Plested ◽  
Iksung Cho ◽  
Jamie Fiske ◽  
...  
Keyword(s):  
Influenza Vaccine ◽  
Hemagglutination Inhibition ◽  
Geometric Mean ◽  
Antibody Responses ◽  
High Dose ◽  
Pivotal Phase ◽  
Post Vaccination ◽  
Treatment Groups ◽  
Cell Responses ◽  
Recombinant Hemagglutinin

Abstract Background Recurrent reports of suboptimal influenza vaccine effectiveness have renewed calls to develop improved, broadly cross-protective influenza vaccines. Here, we evaluated the safety and immunogenicity of a novel, saponin (Matrix-M)–adjuvanted, recombinant hemagglutinin (HA) quadrivalent nanoparticle influenza vaccine (qNIV). Methods We conducted a randomized, observer-blind, comparator-controlled (trivalent high-dose inactivated influenza vaccine [IIV3-HD] or quadrivalent recombinant influenza vaccine [RIV4]), safety and immunogenicity trial of qNIV (5 doses/formulations) in healthy adults ≥65 years. Vaccine immunogenicity was measured by hemagglutination-inhibition assays using reagents that express wild-type hemagglutination inhibition (wt-HAI) sequences and cell-mediated immune responses. Results A total of 1375 participants were randomized, immunized, and followed for safety and immunogenicity. Matrix-M–adjuvanted qNIV induced superior wt-HAI antibody responses against 5 of 6 homologous or drifted strains compared with unadjuvanted qNIV. Adjuvanted qNIV induced post-vaccination wt-HAI antibody responses at day 28 that were statistically higher than IIV3-HD against a panel of homologous or drifted A/H3N2 strains, similar to IIV3-HD against homologous A/H1N1 and B (Victoria) strains and similar to RIV4 against all homologous and drifted strains evaluated. The qNIV formulation with 75 µg Matrix-M adjuvant induced substantially higher post-vaccination geometric mean fold increases of influenza HA-specific polyfunctional CD4+ T cells compared with IIV3-HD or RIV4. Overall, similar frequencies of solicited and unsolicited adverse events were reported in all treatment groups. Conclusions qNIV with 75 µg Matrix-M adjuvant was well tolerated and induced robust antibody and cellular responses, notably against both homologous and drifted A/H3N2 viruses. Further investigation in a pivotal phase 3 trial is underway. Clinical Trials Registration NCT03658629.

scholarly journals Immunogenicity of high-dose influenza vaccination in patients with primary central nervous system malignancy

2018 ◽  
Vol 5 (3) ◽  
pp. 176-183
Author(s):  
Roy E Strowd ◽  
Gregory Russell ◽  
Fang-Chi Hsu ◽  
Annette F Carter ◽  
Michael Chan ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Influenza Vaccine ◽  
Elderly Patients ◽  
Influenza Vaccination ◽  
Standard Dose ◽  
High Grade Glioma ◽  
Cns Lymphoma ◽  
High Dose ◽  
Central Nervous System Malignancy

Abstract Background For cancer patients, rates of influenza-associated hospitalization and death are 4 times greater than that of the general population. Previously, we reported reduced immunogenicity to the standard-dose influenza vaccine in patients with central nervous system malignancy. In other poorly responding populations (eg, elderly patients), high-dose vaccination has improved efficacy and immunogenicity. Methods A prospective cohort study was designed to evaluate the immunogenicity of the Fluzone® high-dose influenza vaccine in brain tumor patients. Data on diagnosis, active oncologic treatment, and immunologic status (eg, CD4 count, CD8 count, CD4:CD8 ratio) were collected. All patients received the high-dose vaccine (180 µg). Hemagglutination inhibition titers were measured at baseline, day 28, and 3 months following vaccination to determine seroconversion (≥4-fold rise) and seroprotection (titer ≥1:40), which were compared to our prior results. Results Twenty-seven patients enrolled. Diagnoses included high-grade glioma (85%), CNS lymphoma (11%), and meningioma (4%). Treatment at enrollment included glucocorticoids (n = 8, 30%), radiation (n = 2, 7%), and chemotherapy (n = 9, 33%). Posttreatment lymphopenia (PTL, CD4 ≤ 200) was observed in 4 patients (15%). High-dose vaccination was well tolerated with no grade III-IV toxicity. Overall, seroconversion rates for the A/H1N1, A/H3N2, and B vaccine strains were significantly higher than in our prior study: 65% vs 37%, 69% vs 23%, and 50% vs 23%, respectively (all P < .04). Seroconversion was universally poor in patients with PTL. While seroprotection at 3 months declined in our prior study, no drop was observed following high-dose vaccination in this cohort. Conclusions The immunologic response to HD influenza vaccination was higher in this cohort than standard-dose influenza vaccination in our prior report. These findings mirror those in elderly patients where high-dose vaccination is the standard of care and raise the possibility of an immunosenescence phenotype.

scholarly journals The Impact of Increasing Prevalence, False Omissions, and Diagnostic Uncertainty on Coronavirus Disease 2019 (COVID-19) Test Performance

2021 ◽  
Author(s):  
Gerald J. Kost
Keyword(s):  
Test Performance ◽  
Influenza A ◽  
Geometric Mean ◽  
False Positives ◽  
Test Quality ◽  
False Negatives ◽  
Predictive Values ◽  
Sensitivity Specificity ◽  
Tier 3 ◽  
The Impact

ABSTRACT Context. Coronavirus disease 2019 (COVID-19) test performance depends on predictive values in settings of increasing disease prevalence. Geospatially distributed diagnostics with minimal uncertainty facilitate efficient point-of-need strategies. Objectives. To use original mathematics to interpret COVID-19 test metrics; assess Food and Drug Administration Emergency Use Authorizations and Health Canada targets; compare predictive values for multiplex, antigen, polymerase chain reaction kit, point-of-care antibody, and home tests; enhance test performance; and improve decision-making. Design. PubMed/newsprint generated articles documenting prevalence. Mathematica and open access software helped perform recursive calculations, graph multivariate relationships, and visualize performance by comparing predictive value geometric mean-squared patterns. Results. Tiered sensitivity/specificity comprise: T1) 90%, 95%; T2) 95%, 97.5%; and T3) 100%, ≥99%. Tier 1 false negatives exceed true negatives at &gt;90.5% prevalence; false positives exceeded true positives at &lt;5.3% prevalence. High sensitivity/specificity tests reduce false negatives and false positives yielding superior predictive values. Recursive testing improves predictive values. Visual logistics facilitate test comparisons. Antigen test quality falls off as prevalence increases. Multiplex severe acute respiratory syndrome (SARS)-CoV-2)*Influenza A/B*Respiratory-Syncytial Virus (RSV) testing performs reasonably well compared to Tier 3. Tier 3 performance with a Tier 2 confidence band lower limit will generate excellent performance and reliability. Conclusions. The overriding principle is select the best combined performance and reliability pattern for the prevalence bracket. Some public health professionals recommend repetitive testing to compensate for low sensitivity. More logically, improved COVID-19 assays with less uncertainty conserve resources. Multiplex differentiation of COVID-19 from Influenza A/B-RSV represents an effective strategy if seasonal flu surges next year.

scholarly journals The impact of the 2009 influenza A(H1N1) pandemic on attitudes of healthcare workers toward seasonal influenza vaccination 2010/11

2011 ◽  
Vol 16 (17) ◽  
Author(s):  
C Brandt ◽  
H F Rabenau ◽  
S Bornmann ◽  
R Gottschalk ◽  
S Wicker
Keyword(s):  
Medical Students ◽  
Influenza Vaccine ◽  
Influenza Vaccination ◽  
Healthcare Workers ◽  
Influenza A ◽  
Influenza Season ◽  
University Hospital ◽  
The Public ◽  
Influenza A H1n1 ◽  
The Impact

The emergence of the influenza A(H1N1)2009 virus provided a major challenge to health services around the world. However, vaccination rates for the public and for healthcare workers (HCWs) have remained low. We performed a study to review the reasons put forward by HCWs to refuse immunisation with the pandemic vaccine in 2009/10 and characterise attitudes in the influenza season 2010/11 due to the emergence of influenza A(H1N1)2009. A survey among HCWs and medical students in the clinical phase of their studies was conducted, using an anonymous questionnaire, at a German university hospital during an influenza vaccination campaign. 1,366 of 3,900 HCWs (35.0%) were vaccinated in the 2010/11 influenza season. Of the vaccinated HCWs, 1,323 (96.9%) completed the questionnaire in addition to 322 vaccinated medical students. Of the 1,645 vaccinees who completed the questionnaire, 712 had not been vaccinated against the influenza A(H1N1)2009 virus in the 2009/10 season. The main reason put forward was the objection to the AS03 adjuvants (239/712, 33.6%). Of the HCWs and students surveyed, 270 of 1,645 (16.4%) stated that the pandemic had influenced their attitude towards vaccination in general. Many German HCWs remained unconvinced of the safety of the pandemic (adjuvanted) influenza vaccine. For this reason, effective risk communication should focus on educating the public and HCWs about influenza vaccine safety and the benefits of vaccination.

scholarly journals Double-Blind, Randomized, Placebo-Controlled Phase II Dose-Finding Study To Evaluate High-Dose Rifampin for Tuberculous Meningitis

2018 ◽  
Vol 62 (12) ◽  
Author(s):  
S. Dian ◽  
V. Yunivita ◽  
A. R. Ganiem ◽  
T. Pramaesya ◽  
L. Chaidir ◽  
...  
Keyword(s):  
Adverse Events ◽  
Phase Ii ◽  
Tuberculous Meningitis ◽  
Standard Dose ◽  
Geometric Mean ◽  
Phase Iii ◽  
High Dose ◽  
Treatment Area ◽  
Double Blind ◽  
Time Curve

ABSTRACT High doses of rifampin may help patients with tuberculous meningitis (TBM) to survive. Pharmacokinetic pharmacodynamic evaluations suggested that rifampin doses higher than 13 mg/kg given intravenously or 20 mg/kg given orally (as previously studied) are warranted to maximize treatment response. In a double-blind, randomized, placebo-controlled phase II trial, we assigned 60 adult TBM patients in Bandung, Indonesia, to standard 450 mg, 900 mg, or 1,350 mg (10, 20, and 30 mg/kg) oral rifampin combined with other TB drugs for 30 days. The endpoints included pharmacokinetic measures, adverse events, and survival. A double and triple dose of oral rifampin led to 3- and 5-fold higher geometric mean total exposures in plasma in the critical early days (2 ± 1) of treatment (area under the concentration-time curve from 0 to 24 h [AUC0–24], 53.5 mg · h/liter versus 170.6 mg · h/liter and 293.5 mg · h/liter, respectively; P < 0.001), with proportional increases in cerebrospinal fluid (CSF) concentrations and without an increase in the incidence of grade 3 or 4 adverse events. The 6-month mortality was 7/20 (35%), 9/20 (45%), and 3/20 (15%) in the 10-, 20-, and 30-mg/kg groups, respectively (P = 0.12). A tripling of the standard dose caused a large increase in rifampin exposure in plasma and CSF and was safe. The survival benefit with this dose should now be evaluated in a larger phase III clinical trial. (This study has been registered at ClinicalTrials.gov under identifier NCT02169882.)

scholarly journals Immunogenicity and safety of a trivalent inactivated influenza vaccine

2011 ◽  
Vol 51 (1) ◽  
pp. 22 ◽  
Author(s):  
Eddy Fadlyana ◽  
Kusnandi Rusmil ◽  
Novilia Sjafri Bachtiar ◽  
Rachmat Gunadi ◽  
Hadyana Sukandar
Keyword(s):  
Influenza Vaccine ◽  
Influenza A ◽  
Geometric Mean ◽  
Deltoid Muscle ◽  
Influenza B ◽  
Serious Adverse Events ◽  
Blood Samples ◽  
Adolescents And Adults ◽  
Antibody Titers ◽  
Influenza Prevention

Background Trivalent inactivated influenza vaccines (TIV) containing antigens of two influenza A strains, A(H1N1) and A(H3N2), and one influenza B strain, are the standard {onnulation for influenza prevention. The vaccines must be updated annually to provide optimal protection against the predicted prevalent strains for the next influenza season.Objective To assess the immunogenidty and safety of the inactivated influenza vaccine (Flubio®) in adolescents and adults, 28 days after a single dose.Methods In this experimental, randomized, single-blind, bridging study, we included 60 healthy adolescents and adults. A single, 0.5 mL dose was administered intramuscularly in the deltoid muscle of the left ann. Blood samples were obtained before and 28 days after immunization. Standardized hemagglutination inhibition (HI) test was used to assess antibody response to influenza antigens.Results From January to February 2010, a total of 60 adolescents and adults enrolled in the study, but two participants did not provide the required blood samples. One hundred percent of the subjects had an anti-influenza titer ≥ 1:40 HI units to all three strains, A/Brisbane/59/2007 (H1N1), A/Uruguay/716/2007 (H3N2), and B/Brisbane/60/2008 (P=1.000) after immunization. The Geometric Mean Titers (GMT) after immunization increasedfor all strains: A/Brisbane, 76.4 to 992.7, A/Uruguay, 27.6 to 432.1, and B/Brisbane, 19.9 to 312.7. Twenty eight days after immunization, we found a 4 times increase in antibody titers in 75.8% of the subjects for A/Brisbane, 84.5% for A/Uruguay, and 77.6% for B/Brisbane. We also observed that 100% of seronegative subjects converted to seropositive for all 3 strains. All vaccines were well-tolerated. There were no serious adverse events reported during the study.Conclusion In adolescents and adults, the Flubio® vaccine was immunogenic and safe.

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