InfluenzaPhase 3NCT00782431

Immunogenicity and Safety Study of an Inactivated Influenza Vaccine (Split Virus, Vero Cell Derived) in Adults Aged 50 Years and Older

A Phase 3 study testing Vero cell derived, trivalent, seasonal influenza vaccine and Licensed egg-derived, trivalent seasonal influenza vaccine in people with Influenza, run by Alachua Government Services, Inc. at 30 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

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Trial summary

Who is it for?: Ages 50 years and olderHealthy volunteers can take part
Conditions the study is for: Influenza
What is being tested?: Vero cell derived, trivalent, seasonal influenza vaccine and Licensed egg-derived, trivalent seasonal influenza vaccine
Type of treatment: Vaccines, Injection or infusion
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 3,208 participants
Where: 30 sitesUnited States
Study dates: Nov 2008to Jul 2009
Phase: Phase 3
Are there results?: Yes, posted in the registrySummary in the doctors' view

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 50 years and older
All sexes
Healthy volunteers accepted
Adult, Older adult

Who may be able to join

Are 50 years of age or older on the day of screening
Have an understanding of the study, agree to its provisions, have the ability to adhere to the provisions of the study and give written informed consent prior to study entry
If female and capable of bearing children,have a negative urine pregnancy test result within 24 hours prior to the vaccination on Study Day 0 and agree to employ adequate birth control measures.

Who cannot join

History of severe allergic reaction or anaphylaxis to egg protein or any other component of the Vero cell-derived influenza vaccine or the egg-derived influenza vaccine
Oral temperature of >= 99.5°F (37.5°C) on the day of vaccination in this study (Note: Subjects meeting this exclusion criterion may be rescheduled for vaccination and study entry at a later date if certain requirements [in the study protocol] are met)
Rash or dermatologic condition or tattoos which may interfere with injection site reaction rating
Blood transfusion or immunoglobulins received within 90 days of study entry
Live vaccine received within 4 weeks or inactivated vaccine or subunit vaccine received within 2 weeks of study entry
Previous vaccination against influenza for the 2008/2009 northern hemisphere influenza season

Show all 12Show fewer

Functional or surgical asplenia (e.g. from a history of hemoglobinopathies, leukemias, or lymphomas)
Diagnosed immunodeficiency as a result of a pathological condition
Pharmacologically induced immunodeficiency as a result of prescribed administration of corticosteroids (e.g., any systemic administration of corticosteroids or an inhaled dose equivalent to 800 mg of beclomethasone dipropionate) or chemotherapeutics or as a result of radiation therapy or any other modality capable of altering normal immunologic response
Known or suspected problem with drug or alcohol abuse
Investigational drug received within 6 weeks prior to study entry or concurrent participating in a clinical study that includes the administration of an investigational product
Subjects who are a member of the team conducting this study or are in a dependent relationship with the study investigator. Dependent relationships include close relatives (i.e., children, spouse/partner, siblings, parents) as well as employees of the investigator.

Trial locations and contacts

30 sites in 1 country.

City, postcode or hospital

30 sites in 1 country

United States30 sites

Benchmark Research Austin
Austin, Texas, 78705
Clinical Research of South Florida
Coral Gables, Florida, 33134
Regional Clinical Research, Inc.
Endwell, New York, 13760
Pi-Coor Clinical Research
Fairfax, Virginia, 22030
Benchmark Research Ft. Worth
Fort Worth, Texas, 76135
Jacksonville Center for Clinical Research
Jacksonville, Florida, 32216
Center for Pharmaceutical Research
Kansas City, Missouri, 64114
Johnson County Clin-Trials
Lenexa, Kansas, 66219
Central Kentucky Research Associates, Inc.
Lexington, Kentucky, 40509
Coastal Clinical Research, Inc.
Mobile, Alabama, 36608
Palmetto Medical Research
Mt. Pleasant, South Carolina, 29464
Clinical Research Associates, Inc. - Nashville
Nashville, Tennessee, 37203
Clinical Research Associates of Tidewater
Norfolk, Virginia, 23507
Meridian Clinical Research, LLC
Omaha, Nebraska, 68134
Vince and Associates Clinical Research
Overland Park, Kansas, 66212
University Clinical Research, Inc.
Pembroke Pines, Florida, 33024
Research Across America
Plano, Texas, 75093
Wake Research Associates, LLC
Raleigh, North Carolina, 27612
Rochester Clinical Research Inc.
Rochester, New York, 14609
Benchmark Research, San Francisco
Sacramento, California, 95816
Benchmark Research San Angelo
San Angelo, Texas, 76904
California Research Foundation
San Diego, California, 92103-6204
Benchmark Research San Francisco
San Francisco, California, 94102
Radiant Research, Inc.
St Louis, Missouri, 63141
Sundance Clinical Research
St Louis, Missouri, 63141
Clinical Research Atlanta
Stockbridge, Georgia, 30281
Quality of Life Medical & Research Center, LLC
Tucson, Arizona, 85712
Omega Medical Research
Warwick, Rhode Island, 02886
Heartland Research Associates, LLC
Wichita, Kansas, 67205
Heartland Research Associates LLC
Wichita, Kansas, 67207

Other trials in United States

About this study

Official title: Phase 3 Double Blind Clinical Study of Effectiveness and Safety of Vero Cell-Derived, Trivalent, Seasonal Influenza Vaccine in Adults Aged 50 Years and Older

The purpose of this study is to demonstrate the effectiveness (seroprotection and seroconversion as measured by the hemagglutination inhibition [HI] assay) of an investigational Vero cell-derived, trivalent, seasonal influenza vaccine in adults 50 years of age and older. Subjects will be randomized in a double-blind fashion to receive a single intramuscular injection of either the investigational vaccine or a licensed egg-derived seasonal influenza vaccine. Blood will be drawn from all subjects for a determination of HI antibody titers on Days 0 and 21, body temperature and injection site reactions will be monitored daily for 7 days. In addition, subjects will be monitored for adverse events and rises in body temperature until Day 21 and again until Day 180.

Conditions: Influenza
Being tested: Vero cell derived, trivalent, seasonal influenza vaccine, Licensed egg-derived, trivalent seasonal influenza vaccine
Medical subject headings: Influenza, Human

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

Vero cell derived, trivalent, seasonal influenza vaccineBiological
Single intramuscular injection
Licensed egg-derived, trivalent seasonal influenza vaccineBiological
Single intramuscular injection

Study groups in NCT00782431
Study group	Role	What they receive
1	Experimental	Vero cell-derived, trivalent, seasonal influenza vaccine Receives: Biological: Vero cell derived, trivalent, seasonal influenza vaccine
2	Active comparator	Licensed egg-derived, trivalent seasonal influenza vaccine Receives: Biological: Licensed egg-derived, trivalent seasonal influenza vaccine

What is being measured

The primary outcome is the main question the study is designed to answer.

Percentage of Subjects With Seroconversion Antibody Titer
The rate of subjects vaccinated that demonstrate seroconversion via hemagglutination inhibition (HI) antibody titer to each of the three antigens contained in the vaccine 21 days after vaccination. Seroconversion is defined as a ≥ 4-fold increase in HI antibody titer from baseline or a HI antibody titer ≥ 40 when there is no detectable HI antibody titer (HI antibody titer < 10) at baseline.
Measured: 21 days
Percentage of Subjects With Seroprotective Antibody Titer
The rate of subjects vaccinated that achieve a reciprocal HI antibody titer of 40 or higher 21 days after vaccination for each of the three antigens contained in the vaccine.
Measured: 21 days

Secondary outcomes (5)

Hemagglutination Inhibition (HI) Antibody Titer for Each of the Three Antigens Contained in the Vaccine at Day 21 After Vaccination
Measured: 21 days
Change of Hemagglutination Inhibition (HI) Antibody Titer at Day 21 Compared to Baseline
Change in geometric mean of titers at day 21 compared to baseline
Measured: 21 days
Rate of Subjects Experiencing Any Injection Site Reactions Until the Day 21 Visit After Vaccination
Measured: 21 days
Rate of Subjects Experiencing Systemic Reactions Until the Day 21 Visit After Vaccination
Measured: 21 days
Rate of Subjects Experiencing Any Systemic Adverse Events During the Entire 180 Day Follow-up Period
Measured: 180 days

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

Nov 2008Jul 2009

First posted31 Oct 2008 (estimated)
Study startNov 2008
Primary completionDec 2008
Study completionJul 2009

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Publications (1)Papers the sponsor has linked to this study.
Other trials for InfluenzaStudies of the same condition, open and under way.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase 3
Primary purpose: Prevention
Allocation: Randomised
Intervention model: Parallel groups
Masking: Double blind
Who is masked: Participant, Investigator
Enrolment: 3,208 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT00782431
Sponsor's protocol ID: 720801
Status last verified: Dec 2025
First submitted: 30 Oct 2008
Last updated: 2 Jan 2026
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: Yes

Publications

Ehrlich HJ, Berezuk G, Fritsch S, Aichinger G, Singer J, Portsmouth D, Hart MK, El-Amin W, Kistner O, Barrett PN. Clinical development of a Vero cell culture-derived seasonal influenza vaccine. Vaccine. 2012 Jun 19;30(29):4377-86. doi: 10.1016/j.vaccine.2011.11.114. Epub 2011 Dec 13.
PubMed 22172502

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

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Study at a glance

From the registry record, last updated by the sponsor on 2 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: Phase 3 Double Blind Clinical Study of Effectiveness and Safety of Vero Cell-Derived, Trivalent, Seasonal Influenza Vaccine in Adults Aged 50 Years and Older
ClinicalTrials.gov ID: NCT00782431
Acronym / sponsor ID: 720801
Conditions: Influenza
Phase: Phase 3
Study type: Interventional
Recruitment status: Completed
Enrolment: 3,208 participants (actual)
Lead sponsor: Alachua Government Services, Inc.Industry (pharma, biotech, devices)
Study start: Nov 2008
Primary completion: Dec 2008 (actual)
Study completion: Jul 2009 (actual)
First posted: 31 Oct 2008 (estimated)
Results: Posted 2 Jan 2026

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Study design

Primary purpose: Prevention
Allocation: Randomised
Intervention model: Parallel groups
Masking: Double blind (participant, investigator)
Number of arms: 2

Arm	Type	Receives
1	Experimental	Biological: Vero cell derived, trivalent, seasonal influenza vaccineVero cell-derived, trivalent, seasonal influenza vaccine
2	Active comparator	Biological: Licensed egg-derived, trivalent seasonal influenza vaccineLicensed egg-derived, trivalent seasonal influenza vaccine

Who may qualify

Ages: 50 years and older
Sex: All
Healthy volunteers: Accepted
Age groups: Adult, Older adult

Key inclusion criteria (3 listed)

Are 50 years of age or older on the day of screening
Have an understanding of the study, agree to its provisions, have the ability to adhere to the provisions of the study and give written informed consent prior to study entry
If female and capable of bearing children,have a negative urine pregnancy test result within 24 hours prior to the vaccination on Study Day 0 and agree to employ adequate birth control measures.

Key exclusion criteria (12 listed)

History of severe allergic reaction or anaphylaxis to egg protein or any other component of the Vero cell-derived influenza vaccine or the egg-derived influenza vaccine
Oral temperature of >= 99.5°F (37.5°C) on the day of vaccination in this study (Note: Subjects meeting this exclusion criterion may be rescheduled for vaccination and study entry at a later date if certain requirements [in the study protocol] are met)
Rash or dermatologic condition or tattoos which may interfere with injection site reaction rating
Blood transfusion or immunoglobulins received within 90 days of study entry
Live vaccine received within 4 weeks or inactivated vaccine or subunit vaccine received within 2 weeks of study entry

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
Vero cell derived, trivalent, seasonal influenza vaccineSingle intramuscular injection	Biological	1
Licensed egg-derived, trivalent seasonal influenza vaccineSingle intramuscular injection	Biological	2

Primary outcome

Percentage of Subjects With Seroconversion Antibody Titer
Time frame: 21 days
The rate of subjects vaccinated that demonstrate seroconversion via hemagglutination inhibition (HI) antibody titer to each of the three antigens contained in the vaccine 21 days after vaccination. Seroconversion is defined as a ≥ 4-fold increase in HI antibody titer from baseline or a HI antibody titer ≥ 40 when there is no detectable HI antibody titer (HI antibody titer < 10) at baseline.
Percentage of Subjects With Seroprotective Antibody Titer
Time frame: 21 days
The rate of subjects vaccinated that achieve a reciprocal HI antibody titer of 40 or higher 21 days after vaccination for each of the three antigens contained in the vaccine.

5 secondary outcomes

Hemagglutination Inhibition (HI) Antibody Titer for Each of the Three Antigens Contained in the Vaccine at Day 21 After Vaccination
Time frame: 21 days
Change of Hemagglutination Inhibition (HI) Antibody Titer at Day 21 Compared to Baseline
Time frame: 21 days
Rate of Subjects Experiencing Any Injection Site Reactions Until the Day 21 Visit After Vaccination
Time frame: 21 days
Rate of Subjects Experiencing Systemic Reactions Until the Day 21 Visit After Vaccination
Time frame: 21 days
Rate of Subjects Experiencing Any Systemic Adverse Events During the Entire 180 Day Follow-up Period
Time frame: 180 days

Results and safety

Results posted to the registry on 2 Jan 2026, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
VCIV (50-64 Years)	839	829
VCIV (65+ Years)	478	474
EIV (50-64 Years)	229	227
EIV (65+ Years)	137	136
VCIV + EIV (50-64 Years)	923	923
VCIV + EIV (65+ Years)	602	602

Primary outcome: Percentage of Subjects With Seroconversion Antibody Titer

Time frame: 21 days. Number (95% Confidence Interval). Unit: percentage of participants

Measure	VCIV (50-64 Years) n = 1730	VCIV (65+ Years) n = 1066	EIV (50-64 Years) n = 221	EIV (65+ Years) n = 134
A/H1N1	47.1 (44.7 to 49.5)	36.8 (33.9 to 39.7)	63.8 (57.1 to 70.1)	37.3 (29.1 to 46.1)
A/H3N2	68.3 (66.1 to 70.5)	58.1 (55 to 61.1)	85.1 (79.7 to 89.5)	67.9 (59.3 to 75.7)
B	46.6 (44.2 to 49)	36.3 (33.4 to 39.3)	62.9 (56.2 to 69.3)	51.5 (42.7 to 60.2)

Population analysed: Intent-to-treat dataset contains all randomized and vaccinated subjects with immunogenicity data available at baseline and Day 21 for at least one strain.

Primary outcome: Percentage of Subjects With Seroprotective Antibody Titer

Time frame: 21 days. Number (95% Confidence Interval). Unit: percentage of participants

Measure	VCIV (50-64 Years) n = 1730	VCIV (65+ Years) n = 1066	EIV (50-64 Years) n = 221	EIV (65+ Years) n = 134
A/H1N1 Day 1	29.6 (27.5 to 31.8)	35.3 (32.4 to 38.2)	26.7 (21 to 33)	36.6 (28.4 to 45.3)
A/H1N1 Day 21	74.3 (72.2 to 76.4)	72.6 (69.8 to 75.3)	86.9 (81.7 to 91)	75.4 (67.2 to 82.4)
A/H3N2 Day 1	43.1 (40.8 to 45.5)	58 (54.9 to 61)	44.8 (38.1 to 51.6)	51.5 (42.7 to 60.2)
A/H3N2 Day 21	90 (88.5 to 91.4)	91.3 (89.4 to 92.9)	95.9 (92.4 to 98.1)	95.5 (90.5 to 98.3)
B Day 1	45.7 (43.4 to 48.1)	49.1 (46 to 52.1)	42.1 (35.5 to 48.9)	52.2 (43.4 to 60.9)
B Day 21	86.2 (84.5 to 87.8)	82.6 (80.2 to 84.9)	93.7 (89.6 to 96.5)	94.8 (89.5 to 97.9)

Population analysed: Intent-to-treat dataset contains all randomized and vaccinated subjects with immunogenicity data available at baseline and Day 21 for at least one strain.

5 secondary outcomes are reported in the full results.

Adverse events

Other adverse events reported at 4% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
VCIV (50-64 Years)	32 of 828 (3.9%)	777 of 828 (93.8%)	1 of 828
VCIV (65+ Years)	28 of 474 (5.9%)	297 of 474 (62.7%)	3 of 474
EIV (50-64 Years)	4 of 227 (1.8%)	183 of 227 (80.6%)	0 of 227
EIV (65+ Years)	10 of 136 (7.4%)	95 of 136 (69.9%)	0 of 136
VCIV + EIV (50-64 Years)	25 of 923 (2.7%)	492 of 923 (53.3%)	1 of 923
VCIV + EIV (65+ Years)	32 of 602 (5.3%)	346 of 602 (57.5%)	1 of 602

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 2 Jan 2026.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Derived from this study: PubMed 22172502Ehrlich HJ, Berezuk G, Fritsch S, Aichinger G, Singer J, Portsmouth D, Hart MK, El-Amin W, Kistner O, Barrett PN. Clinical development of a Vero cell culture-derived seasonal influenza vaccine. Vaccine. 2012 Jun 19;30(29):4377-86. doi: 10.1016/j.vaccine.2011.11.114. Epub 2011 Dec 13.

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Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

The record lists no contact. Use the official record to reach the sponsor.

30 sites in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 3 inclusion and 12 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 2 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 30 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

Yes. Results are posted in the registry (first posted 2 Jan 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Percentage of Subjects With Seroconversion Antibody Titer (time frame: 21 days). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT00782431, which also lists 1 linked publication.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 2 Jan 2026.