Clostridium Difficile Associated DiseasePhase 3NCT03579459

Evaluation Of Clostridium Difficile Vaccine Lot Consistency In Healthy Adults 65 To 85 Years Of Age

A Phase 3 study testing Clostridium difficile vaccine in people with Clostridium Difficile Associated Disease, run by Pfizer at 24 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

This study will investigate a Clostridium difficile vaccine in healthy adults 65 to 85 years of age, who will each receive 3 doses of vaccine. The study will assess the lot consistency, safety, and tolerability of the vaccine, and also look at the subjects' immune response to the vaccine. Read more about this study

Who is it for?: Ages 65 to 85 yearsHealthy volunteers can take part
Conditions the study is for: Clostridium Difficile Associated Disease
What is being tested?: Clostridium difficile vaccine
Type of treatment: Vaccines
Could I receive a placebo?: Yes, some participants may receive a placebo
How many people: 1,317 participants
Where: 24 sitesUnited States
Study dates: 31 Jul 2018to 6 Aug 2019
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 65 to 85 years
All sexes
Healthy volunteers accepted
Older adult

Who may be able to join

Evidence of a personally signed and dated informed consent document.
Willing and able to comply with study procedures.
Healthy adults 65 to 85 years of age.
Male subjects or female subjects who are not of childbearing potential.
Ability to be contacted by telephone during study participation.

Who cannot join

Investigator site staff members directly involved in the conduct of the study and their family members, site staff members otherwise supervised by the investigator, or subjects who are Pfizer employees, including their family members, directly involved in the conduct of the study.
Participation in other studies involving investigational drug(s)/vaccine(s) within 28 days prior to study entry through conclusion of the study.
Previous administration of an investigational C difficile vaccine or C difficile monoclonal antibody therapy.
Proven or suspected prior episode of C difficile infection.
Unstable chronic medical condition or disease requiring significant change in therapy or hospitalization for worsening disease within 8 weeks before receipt of investigational product.
Serious chronic medical disorders, including metastatic malignancy, severe chronic obstructive pulmonary disease (COPD) requiring supplemental oxygen, end-stage renal disease with or without dialysis, clinically unstable cardiac disease.

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Any bleeding disorder or anticoagulant therapy that would contraindicate intramuscular injection.
Any contraindication to vaccination or vaccine components, including previous anaphylactic reaction to any vaccine or vaccine-related components.
Subjects who may be unable to respond to vaccination due to:
Congenital or acquired immunodeficiency.
Receipt of systemic corticosteroids (greater than or equal to 20 mg/day of prednisone or equivalent) for greater than or equal to 14 days within 28 days of enrollment.
Receipt of chronic systemic treatment with other known immunosuppressant medications, or radiotherapy, within 6 months of enrollment.
Underlying bone marrow disorder treated within the past year, such as myelodysplasia, myeloma, or myeloproliferative disorder, treated within the past year, or any history of bone marrow transplant.
Malignancy that required treatment with chemotherapy (including the use of adjunctive and hormonal therapy), immunotherapy, radiation therapy, or antineoplastic target therapies within the past 24 months.
Receipt of blood products or immunoglobulins within 6 months before enrollment through conclusion of the study.
Residence in a nursing home or other long-term care facility, or requirement for semiskilled nursing care or assisted living. An ambulatory subject who lives in an autonomous manner in a retirement home or village is eligible for the trial.
A known infection with human immunodeficiency virus (HIV).
Other acute or chronic medical or psychiatric condition including recent (within the past year) or active suicidal ideation or behavioral or laboratory abnormality that may increase the risk associated with study participation or investigational product administration or may interfere with the interpretation of study results.
Female subjects of childbearing potential; pregnant female subjects; breastfeeding female subjects; fertile male subjects who are unwilling or unable to use a highly effective method of contraception as outlined in this protocol for the duration of the study and for at least 28 days after the last dose of investigational product.

Trial locations and contacts

24 sites in 1 country.

City, postcode or hospital

24 sites in 1 country

United States24 sites

Atlanta Center for Medical Research
Atlanta, Georgia, 30331
Benchmark Research
Austin, Texas, 78705
PMG Research of Charlotte, LLC
Charlotte, North Carolina, 28209
Clinical Research of South Florida
Coral Gables, Florida, 33134
Avail Clinical Research, LLC
DeLand, Florida, 32720
J. Lewis Research Inc. / Foothill Family Clinic Draper
Draper, Utah, 84020
Medical Research South, LLC
Goose Creek, South Carolina, 29445
Research Centers of America, LLC
Hollywood, Florida, 33024
East-West Medical Research Institute
Honolulu, Hawaii, 96814
Advanced Clinical Research
Meridian, Idaho, 83642
Coastal Clinical Research, Inc.
Mobile, Alabama, 36608
Ochsner Clinic Foundation
New Orleans, Louisiana, 70121
Meridian Clinical Research, LLC
Norfolk, Nebraska, 68701
Lynn Health Science Institute
Oklahoma City, Oklahoma, 73112
Meridian Clinical Research, LLC
Omaha, Nebraska, 68134
Amici Clinical Research
Raritan, New Jersey, 08869
Paradigm Clinical Research Centers, Inc.
Redding, California, 96001
J. Lewis Research, Inc./ Foothill Family Clinic South
Salt Lake City, Utah, 84109
J. Lewis Research, Incorporated/Foothill Family Clinic South
Salt Lake City, Utah, 84121
Diagnostics Research Group
San Antonio, Texas, 78229
J. Lewis Research, Inc. / Jordan River Family Medicine
South Jordan, Utah, 84095
Clinical Research Atlanta
Stockbridge, Georgia, 30281
Heartland Research Associates, LLC
Wichita, Kansas, 67207
PMG Research of Wilmington, LLC
Wilmington, North Carolina, 28401

Other trials in United States

About this study

Official title: A PHASE 3, PLACEBO-CONTROLLED, RANDOMIZED, OBSERVER-BLINDED STUDY TO EVALUATE THE LOT CONSISTENCY, SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF A CLOSTRIDIUM DIFFICILE VACCINE IN HEALTHY ADULTS 65 TO 85 YEARS OF AGE

Read the detailed description

Serology for B5091008 was delayed due to discussions with the FDA on statistical analysis as well as delays attributed to the COVID pandemic.

Conditions: Clostridium Difficile Associated Disease
Being tested: Clostridium difficile vaccine, placebo
Keywords: Clostridium Difficile, vaccine

What participants receive

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

Clostridium difficile vaccineBiological
Toxoid based Clostridium difficile vaccine
placeboBiological
Also called 0.9% sodium chloride
Normal saline solution

Study groups in NCT03579459
Study group	Role	What they receive
Clostridium difficile vaccine Lot 1	Active comparator	Not described Receives: Biological: Clostridium difficile vaccine
Clostridium difficile vaccine Lot 2	Active comparator	Not described Receives: Biological: Clostridium difficile vaccine
Clostridium difficile vaccine Lot 3	Active comparator	Not described Receives: Biological: Clostridium difficile vaccine
Placebo	Placebo comparator	Normal saline solution (0.9% sodium chloride) Receives: Biological: placebo

What is being measured

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

Geometric Mean Concentrations (GMCs) of Clostridium Difficile Toxin A and Toxin B Specific Neutralizing Antibodies at Month 7
GMC was calculated as the mean of the assay results after making the logarithm transformation and then back transformation to its original scale. Confidence intervals (CIs) were back transformations of CIs based on the Student t distribution for the mean logarithm of the concentrations. Clostridium difficile toxin A and toxin B were inactivated by a combination of genetic mutations to decrease toxin activity and chemical treatments were done prior to final purification and formulation of the drug substance.
Measured: At Month 7
Percentage of Participants Reporting Local Reactions by Maximum Severity Within 7 Days After Vaccination 1
Local reactions included pain at injection site, redness and swelling. These were recorded by participants in an electronic diary (e-diary). Pain at injection site was graded as mild: did not interfere with daily activity, moderate: interfered with daily activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Redness and swelling were measured and recorded in measuring device units. One measuring device unit= 0.5 centimeter (cm) and graded as mild: 2.5 to 5.0 cm, moderate: greater than (>) 5.0 to 10.0 cm, severe: >10.0 cm, Grade 4 indicated necrosis or exfoliative dermatitis for redness and necrosis for swelling. The maximum severity was defined as highest grading of each local reaction within 7 days of vaccination. Events were classified as Grade 4 based on study investigator's judgement.
Measured: Within 7 days after Vaccination 1 at Month 0
Percentage of Participants Reporting Local Reactions by Maximum Severity Within 7 Days After Vaccination 2
Local reactions included pain at injection site, redness and swelling. These were recorded by participants in an e-diary. Pain at injection site was graded as mild: did not interfere with daily activity, moderate: interfered with daily activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Redness and swelling were measured and recorded in measuring device units. One measuring device unit= 0.5 cm and graded as mild: 2.5 to 5.0 cm, moderate: > 5.0 to 10.0 cm, severe: >10.0 cm, Grade 4 indicated necrosis or exfoliative dermatitis for redness and necrosis for swelling. The maximum severity was defined as highest grading of each local reaction within 7 days of vaccination. Events were classified as Grade 4 based on study investigator's judgement.
Measured: Within 7 days after Vaccination 2 at Month 1
Percentage of Participants Reporting Local Reactions by Maximum Severity Within 7 Days After Vaccination 3
Local reactions included pain at injection site, redness and swelling. These were recorded by participants in an e-diary. Pain at injection site was graded as mild: did not interfere with daily activity, moderate: interfered with daily activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Redness and swelling were measured and recorded in measuring device units. One measuring device unit= 0.5 cm and graded as mild: 2.5 to 5.0 cm, moderate: > 5.0 to 10.0 cm, severe: >10.0 cm, Grade 4 indicated necrosis or exfoliative dermatitis for redness and necrosis for swelling. The maximum severity was defined as highest grading of each local reaction within 7 days of vaccination. Events were classified as Grade 4 based on study investigator's judgement.
Measured: Within 7 days after Vaccination 3 at Month 6
Percentage of Participants Reporting Systemic Events by Maximum Severity Within 7 Days After Vaccination 1
Systemic events included fever, fatigue, headache, joint pain, muscle pain and vomiting. These were recorded by participants in an e-diary. Fever was categorized as: mild: (38.0 to 38.4 degree Celsius [deg C]), moderate: (38.5 to 38.9 deg C), severe (39.0 to 40.0 deg C), grade 4: >40 deg C. Fatigue, headache, joint pain and muscle pain were graded as mild: did not interfere with activity, moderate: some interference with activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Vomiting was graded as mild: 1 to 2 times in 24 hours, moderate: >2 times in 24 hours, severe: required intravenous hydration, grade 4: emergency room visit or hospitalization for hypotensive shock. The maximum severity was defined as highest grading of each systemic event within 7 days of vaccination. Events were classified as Grade 4 based on study investigator's judgement.
Measured: Within 7 days after Vaccination 1 at Month 0
Percentage of Participants Reporting Systemic Events by Maximum Severity Within 7 Days After Vaccination 2
Systemic events included fever, fatigue, headache, joint pain, muscle pain and vomiting. These were recorded by participants in an e-diary. Fever was categorized as: mild: (38.0 to 38.4 deg C), moderate: (38.5 to 38.9 deg C), severe (39.0 to 40.0 deg C), grade 4: >40 deg C. Fatigue, headache, joint pain and muscle pain were graded as mild: did not interfere with activity, moderate: some interference with activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Vomiting was graded as mild: 1 to 2 times in 24 hours, moderate: >2 times in 24 hours, severe: required intravenous hydration, grade 4: emergency room visit or hospitalization for hypotensive shock. The maximum severity was defined as highest grading of each systemic event within 7 days of vaccination. Events were classified as Grade 4 based on study investigator's judgement.
Measured: Within 7 days after Vaccination 2 at Month 1
Percentage of Participants Reporting Systemic Events by Maximum Severity Within 7 Days After Vaccination 3
Systemic events included fever, fatigue, headache, joint pain, muscle pain and vomiting. These were recorded by participants in an e-diary. Fever was categorized as: mild: (38.0 to 38.4 deg C), moderate: (38.5 to 38.9 deg C), severe (39.0 to 40.0 deg C), grade 4: >40 deg C. Fatigue, headache, joint pain and muscle pain were graded as mild: did not interfere with activity, moderate: some interference with activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Vomiting was graded as mild: 1 to 2 times in 24 hours, moderate: >2 times in 24 hours, severe: required intravenous hydration, grade 4: emergency room visit or hospitalization for hypotensive shock. The maximum severity was defined as highest grading of each systemic event within 7 days of vaccination. Events were classified as Grade 4 based on study investigator's judgement.
Measured: Within 7 days after Vaccination 3 at Month 6
Percentage of Participants With Adverse Events (AEs) Through 1 Month After Last Study Vaccination
An AE was defined as any untoward medical occurrence in a participant who received investigational product without regard to possibility of causal relationship. AEs included both serious and all non-serious adverse events (NSAEs). Only AEs and NSAEs collected by non-systematic assessment (i.e., excluding local reactions and systemic events) were reported in this outcome measure.
Measured: From Day 1 to 1 month after last vaccination (Up to Month 7)
Percentage of Participants Reporting Serious Adverse Events (SAEs)
An SAE was defined as any untoward medical occurrence at any dose that resulted in any of the following outcomes: death; life-threatening (immediate risk of death); required inpatient hospitalization or prolongation of existing hospitalization; persistent or significant disability/incapacity (substantial disruption of the ability to conduct normal life functions); congenital anomaly/birth defect; or that was considered as an important medical event.
Measured: From Day 1 to 1 month after last vaccination (Up to Month 7)

Timeline

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

31 Jul 20186 Aug 2019

First posted6 Jul 2018
Study start31 Jul 2018
Primary completion6 Aug 2019
Study completion6 Aug 2019

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 Clostridium Difficile Associated DiseaseStudies of the same condition, open and under way.
More trials run by PfizerThe sponsor's other registered studies.
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: Triple blind
Who is masked: Participant, Investigator, Outcomes assessor
Enrolment: 1,317 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT03579459
Sponsor's protocol ID: B5091008
Status last verified: Dec 2022
First submitted: 25 Jun 2018
Last updated: 19 Jan 2023
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: Yes
FDA-regulated drug: Yes
FDA-regulated device: No
Individual data sharing: Yes: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.

Publications

Christensen S, Bouguermouh S, Ilangovan K, Pride MW, Webber C, Lockhart SP, Shah R, Kitchin N, Lamberth E, Zhang H, Gao Q, Brock L, Anderson AS, Gruber WC. A phase 3 study evaluating the lot consistency, immunogenicity, safety, and tolerability of a Clostridioides difficile vaccine in healthy adults 65 to 85 years of age. Vaccine. 2023 Dec 7;41(50):7548-7559. doi: 10.1016/j.vaccine.2023.11.003. Epub 2023 Nov 17.
PubMed 37977942

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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A Study to Learn About a Clostridioides Difficile Vaccine in People 65 Years of Age and Older
Clostridoides Difficile Associated Disease
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REMBRANDT: REcovery of the MicroBiome fRom Antibiotics for Dental implanTs
Dysbiosis, Clostridium Difficile
RecruitingObservational study
Natural History of Clostridioides Difficile Infection
Clostridium Difficile Infection, Health Care Associated Infection
RecruitingPhase 2/3
Secondary Prevention of Clostridioides Difficile Using Vancomycin
Clostridioides Difficile Infection, Clostridioides Difficile Infection Recurrence
RecruitingObservational study
Role of Bile Acids and Microbiota in Clostridioides Difficile Infection in Ulcerative Colitis
Ulcerative Colitis

All Clostridium Difficile Associated Disease trials

Study at a glance

From the registry record, last updated by the sponsor on 19 Jan 2023. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A PHASE 3, PLACEBO-CONTROLLED, RANDOMIZED, OBSERVER-BLINDED STUDY TO EVALUATE THE LOT CONSISTENCY, SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF A CLOSTRIDIUM DIFFICILE VACCINE IN HEALTHY ADULTS 65 TO 85 YEARS OF AGE
ClinicalTrials.gov ID: NCT03579459
Acronym / sponsor ID: B5091008
Conditions: Clostridium Difficile Associated Disease
Keywords: Clostridium Difficile, vaccine
Phase: Phase 3
Study type: Interventional
Recruitment status: Completed
Enrolment: 1,317 participants (actual)
Lead sponsor: PfizerIndustry (pharma, biotech, devices)
Study start: 31 Jul 2018 (actual)
Primary completion: 6 Aug 2019 (actual)
Study completion: 6 Aug 2019 (actual)
First posted: 6 Jul 2018 (actual)
Results: Posted 19 Jan 2023

Clinical summary

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

Detailed description

Serology for B5091008 was delayed due to discussions with the FDA on statistical analysis as well as delays attributed to the COVID pandemic.

Study design

Primary purpose: Prevention
Allocation: Randomised
Intervention model: Parallel groups
Masking: Triple blind (participant, investigator, outcomes assessor)
Number of arms: 4

Arm	Type	Receives
Clostridium difficile vaccine Lot 1	Active comparator	Biological: Clostridium difficile vaccine
Clostridium difficile vaccine Lot 2	Active comparator	Biological: Clostridium difficile vaccine
Clostridium difficile vaccine Lot 3	Active comparator	Biological: Clostridium difficile vaccine
Placebo	Placebo comparator	Biological: placeboNormal saline solution (0.9% sodium chloride)

Who may qualify

Ages: 65 to 85 years
Sex: All
Healthy volunteers: Accepted
Age groups: Older adult

Key inclusion criteria (5 listed)

Evidence of a personally signed and dated informed consent document.
Willing and able to comply with study procedures.
Healthy adults 65 to 85 years of age.
Male subjects or female subjects who are not of childbearing potential.
Ability to be contacted by telephone during study participation.

Key exclusion criteria (19 listed)

Investigator site staff members directly involved in the conduct of the study and their family members, site staff members otherwise supervised by the investigator, or subjects who are Pfizer employees, including their family members, directly involved in the conduct of the study.
Participation in other studies involving investigational drug(s)/vaccine(s) within 28 days prior to study entry through conclusion of the study.
Previous administration of an investigational C difficile vaccine or C difficile monoclonal antibody therapy.
Proven or suspected prior episode of C difficile infection.
Unstable chronic medical condition or disease requiring significant change in therapy or hospitalization for worsening disease within 8 weeks before receipt of investigational product.

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
Clostridium difficile vaccineToxoid based Clostridium difficile vaccine	Biological	Clostridium difficile vaccine Lot 1, Clostridium difficile vaccine Lot 2, Clostridium difficile vaccine Lot 3
placeboAlso: 0.9% sodium chlorideNormal saline solution	Biological	Placebo

Primary outcome

Geometric Mean Concentrations (GMCs) of Clostridium Difficile Toxin A and Toxin B Specific Neutralizing Antibodies at Month 7
Time frame: At Month 7
GMC was calculated as the mean of the assay results after making the logarithm transformation and then back transformation to its original scale. Confidence intervals (CIs) were back transformations of CIs based on the Student t distribution for the mean logarithm of the concentrations. Clostridium difficile toxin A and toxin B were inactivated by a combination of genetic mutations to decrease toxin activity and chemical treatments were done prior to final purification and formulation of the drug substance.
Percentage of Participants Reporting Local Reactions by Maximum Severity Within 7 Days After Vaccination 1
Time frame: Within 7 days after Vaccination 1 at Month 0
Local reactions included pain at injection site, redness and swelling. These were recorded by participants in an electronic diary (e-diary). Pain at injection site was graded as mild: did not interfere with daily activity, moderate: interfered with daily activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Redness and swelling were measured and recorded in measuring device units. One measuring device unit= 0.5 centimeter (cm) and graded as mild: 2.5 to 5.0 cm, moderate: greater than (>) 5.0 to 10.0 cm, severe: >10.0 cm, Grade 4 indicated necrosis or exfoliative dermatitis for redness and necrosis for swelling. The maximum severity was defined as highest grading of each local reaction within 7 days of vaccination. Events were classified as Grade 4 based on study investigator's judgement.
Percentage of Participants Reporting Local Reactions by Maximum Severity Within 7 Days After Vaccination 2
Time frame: Within 7 days after Vaccination 2 at Month 1
Local reactions included pain at injection site, redness and swelling. These were recorded by participants in an e-diary. Pain at injection site was graded as mild: did not interfere with daily activity, moderate: interfered with daily activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Redness and swelling were measured and recorded in measuring device units. One measuring device unit= 0.5 cm and graded as mild: 2.5 to 5.0 cm, moderate: > 5.0 to 10.0 cm, severe: >10.0 cm, Grade 4 indicated necrosis or exfoliative dermatitis for redness and necrosis for swelling. The maximum severity was defined as highest grading of each local reaction within 7 days of vaccination. Events were classified as Grade 4 based on study investigator's judgement.
Percentage of Participants Reporting Local Reactions by Maximum Severity Within 7 Days After Vaccination 3
Time frame: Within 7 days after Vaccination 3 at Month 6
Local reactions included pain at injection site, redness and swelling. These were recorded by participants in an e-diary. Pain at injection site was graded as mild: did not interfere with daily activity, moderate: interfered with daily activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Redness and swelling were measured and recorded in measuring device units. One measuring device unit= 0.5 cm and graded as mild: 2.5 to 5.0 cm, moderate: > 5.0 to 10.0 cm, severe: >10.0 cm, Grade 4 indicated necrosis or exfoliative dermatitis for redness and necrosis for swelling. The maximum severity was defined as highest grading of each local reaction within 7 days of vaccination. Events were classified as Grade 4 based on study investigator's judgement.
Percentage of Participants Reporting Systemic Events by Maximum Severity Within 7 Days After Vaccination 1
Time frame: Within 7 days after Vaccination 1 at Month 0
Systemic events included fever, fatigue, headache, joint pain, muscle pain and vomiting. These were recorded by participants in an e-diary. Fever was categorized as: mild: (38.0 to 38.4 degree Celsius [deg C]), moderate: (38.5 to 38.9 deg C), severe (39.0 to 40.0 deg C), grade 4: >40 deg C. Fatigue, headache, joint pain and muscle pain were graded as mild: did not interfere with activity, moderate: some interference with activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Vomiting was graded as mild: 1 to 2 times in 24 hours, moderate: >2 times in 24 hours, severe: required intravenous hydration, grade 4: emergency room visit or hospitalization for hypotensive shock. The maximum severity was defined as highest grading of each systemic event within 7 days of vaccination. Events were classified as Grade 4 based on study investigator's judgement.
Percentage of Participants Reporting Systemic Events by Maximum Severity Within 7 Days After Vaccination 2
Time frame: Within 7 days after Vaccination 2 at Month 1
Systemic events included fever, fatigue, headache, joint pain, muscle pain and vomiting. These were recorded by participants in an e-diary. Fever was categorized as: mild: (38.0 to 38.4 deg C), moderate: (38.5 to 38.9 deg C), severe (39.0 to 40.0 deg C), grade 4: >40 deg C. Fatigue, headache, joint pain and muscle pain were graded as mild: did not interfere with activity, moderate: some interference with activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Vomiting was graded as mild: 1 to 2 times in 24 hours, moderate: >2 times in 24 hours, severe: required intravenous hydration, grade 4: emergency room visit or hospitalization for hypotensive shock. The maximum severity was defined as highest grading of each systemic event within 7 days of vaccination. Events were classified as Grade 4 based on study investigator's judgement.
Percentage of Participants Reporting Systemic Events by Maximum Severity Within 7 Days After Vaccination 3
Time frame: Within 7 days after Vaccination 3 at Month 6
Systemic events included fever, fatigue, headache, joint pain, muscle pain and vomiting. These were recorded by participants in an e-diary. Fever was categorized as: mild: (38.0 to 38.4 deg C), moderate: (38.5 to 38.9 deg C), severe (39.0 to 40.0 deg C), grade 4: >40 deg C. Fatigue, headache, joint pain and muscle pain were graded as mild: did not interfere with activity, moderate: some interference with activity, severe: prevented daily activity, grade 4: emergency room visit or hospitalization. Vomiting was graded as mild: 1 to 2 times in 24 hours, moderate: >2 times in 24 hours, severe: required intravenous hydration, grade 4: emergency room visit or hospitalization for hypotensive shock. The maximum severity was defined as highest grading of each systemic event within 7 days of vaccination. Events were classified as Grade 4 based on study investigator's judgement.
Percentage of Participants With Adverse Events (AEs) Through 1 Month After Last Study Vaccination
Time frame: From Day 1 to 1 month after last vaccination (Up to Month 7)
An AE was defined as any untoward medical occurrence in a participant who received investigational product without regard to possibility of causal relationship. AEs included both serious and all non-serious adverse events (NSAEs). Only AEs and NSAEs collected by non-systematic assessment (i.e., excluding local reactions and systemic events) were reported in this outcome measure.
Percentage of Participants Reporting Serious Adverse Events (SAEs)
Time frame: From Day 1 to 1 month after last vaccination (Up to Month 7)
An SAE was defined as any untoward medical occurrence at any dose that resulted in any of the following outcomes: death; life-threatening (immediate risk of death); required inpatient hospitalization or prolongation of existing hospitalization; persistent or significant disability/incapacity (substantial disruption of the ability to conduct normal life functions); congenital anomaly/birth defect; or that was considered as an important medical event.

Results and safety

Results posted to the registry on 19 Jan 2023, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
Clostridium Difficile Vaccine: Lot 1	330	301
Clostridium Difficile Vaccine: Lot 2	327	304
Clostridium Difficile Vaccine: Lot 3	328	305
Placebo	332	308

Primary outcome: Geometric Mean Concentrations (GMCs) of Clostridium Difficile Toxin A and Toxin B Specific Neutralizing Antibodies at Month 7

Time frame: At Month 7. Geometric mean (95% Confidence Interval). Unit: Neutralization units per mL

Measure	Clostridium Difficile Vaccine: Lot 1 n = 286	Clostridium Difficile Vaccine: Lot 2 n = 284	Clostridium Difficile Vaccine: Lot 3 n = 296
Toxin A	878.8 (786.3 to 982.2)	873.0 (779.2 to 978.1)	872.9 (782.6 to 973.5)
Toxin B	5823.9 (5041.0 to 6728.4)	5462.8 (4733.4 to 6304.7)	5426.0 (4724.4 to 6231.8)

Clostridium Difficile Vaccine: Lot 1 vs Clostridium Difficile Vaccine: Lot 2: Geometric Mean ratio (GMR): 1.01 (95% CI 0.86 to 1.18)
Clostridium Difficile Vaccine: Lot 1 vs Clostridium Difficile Vaccine: Lot 3: GMR: 1.01 (95% CI 0.86 to 1.18)
Clostridium Difficile Vaccine: Lot 2 vs Clostridium Difficile Vaccine: Lot 3: GMR: 1.00 (95% CI 0.85 to 1.17)

Population analysed: Evaluable immunogenicity(EI)population=enrolled participants who received all 3 doses of investigational product to which they were randomized; blood drawn for analysis within 23-47 days after visit 4(Month 6)had valid, determinate assay results for either toxinA or B for specified analysis and no major protocol deviations. Placebo arm is not reported as GMC was planned to be evaluated only for 3 vaccine lots. Here,'Number Analyzed' refers to number of participants evaluable for specific toxins.

Primary outcome: Percentage of Participants Reporting Local Reactions by Maximum Severity Within 7 Days After Vaccination 1

Time frame: Within 7 days after Vaccination 1 at Month 0. Number (95% Confidence Interval). Unit: Percentage of participants

Measure	Clostridium Difficile Vaccine: Lot 1 n = 325	Clostridium Difficile Vaccine: Lot 2 n = 320	Clostridium Difficile Vaccine: Lot 3 n = 322	Placebo n = 325
Pain at injection site: Mild	14.2 (10.6 to 18.4)	15.9 (12.1 to 20.4)	17.4 (13.4 to 22.0)	4.9 (2.8 to 7.9)
Pain at injection site: Moderate	2.5 (1.1 to 4.8)	0.3 (0.0 to 1.7)	0.9 (0.2 to 2.7)	0 (0.0 to 1.1)
Pain at injection site: Severe	0 (0.0 to 1.1)	0 (0.0 to 1.1)	0.3 (0.0 to 1.7)	0 (0.0 to 1.1)
Pain at injection site: Grade 4	0 (0.0 to 1.1)	0 (0.0 to 1.1)	0 (0.0 to 1.1)	0 (0.0 to 1.1)
Redness: Mild	0.6 (0.1 to 2.2)	1.6 (0.5 to 3.6)	2.2 (0.9 to 4.4)	0.6 (0.1 to 2.2)
Redness: Moderate	0.6 (0.1 to 2.2)	0 (0.0 to 1.1)	0.3 (0.0 to 1.7)	0 (0.0 to 1.1)
Redness: Severe	0.3 (0.0 to 1.7)	0 (0.0 to 1.1)	0 (0.0 to 1.1)	0 (0.0 to 1.1)
Redness: Grade 4	0 (0.0 to 1.1)	0 (0.0 to 1.1)	0 (0.0 to 1.1)	0 (0.0 to 1.1)

Population analysed: Safety analysis population included all participants who received at least 1 dose of the investigational product. Here, "Overall Number of Participants Analyzed" signifies participants evaluable for this outcome measure.

Primary outcome: Percentage of Participants Reporting Local Reactions by Maximum Severity Within 7 Days After Vaccination 2

Time frame: Within 7 days after Vaccination 2 at Month 1. Number (95% Confidence Interval). Unit: Percentage of participants

Measure	Clostridium Difficile Vaccine: Lot 1 n = 316	Clostridium Difficile Vaccine: Lot 2 n = 309	Clostridium Difficile Vaccine: Lot 3 n = 314	Placebo n = 313
Pain at injection site: Mild	22.2 (17.7 to 27.1)	26.9 (22.0 to 32.2)	22.0 (17.5 to 27.0)	4.2 (2.2 to 7.0)
Pain at injection site: Moderate	2.2 (0.9 to 4.5)	2.9 (1.3 to 5.5)	1.6 (0.5 to 3.7)	0.3 (0.0 to 1.8)
Pain at injection site: Severe	0.3 (0.0 to 1.8)	0 (0.0 to 1.2)	0 (0.0 to 1.2)	0 (0.0 to 1.2)
Pain at injection site: Grade 4	0 (0.0 to 1.2)	0 (0.0 to 1.2)	0 (0.0 to 1.2)	0 (0.0 to 1.2)
Redness: Mild	3.5 (1.8 to 6.1)	3.9 (2.0 to 6.7)	1.3 (0.3 to 3.2)	1.0 (0.2 to 2.8)
Redness: Moderate	1.9 (0.7 to 4.1)	1.3 (0.4 to 3.3)	1.3 (0.3 to 3.2)	0.3 (0.0 to 1.8)
Redness: Severe	1.3 (0.3 to 3.2)	0.6 (0.1 to 2.3)	0 (0.0 to 1.2)	0 (0.0 to 1.2)
Redness: Grade 4	0 (0.0 to 1.2)	0 (0.0 to 1.2)	0 (0.0 to 1.2)	0 (0.0 to 1.2)

Primary outcome: Percentage of Participants Reporting Local Reactions by Maximum Severity Within 7 Days After Vaccination 3

Time frame: Within 7 days after Vaccination 3 at Month 6. Number (95% Confidence Interval). Unit: Percentage of participants

Measure	Clostridium Difficile Vaccine: Lot 1 n = 293	Clostridium Difficile Vaccine: Lot 2 n = 295	Clostridium Difficile Vaccine: Lot 3 n = 298	Placebo n = 303
Pain at injection site: Mild	22.5 (17.9 to 27.7)	23.4 (18.7 to 28.6)	27.9 (22.8 to 33.3)	2.6 (1.1 to 5.1)
Pain at injection site: Moderate	1.7 (0.6 to 3.9)	2.0 (0.7 to 4.4)	1.3 (0.4 to 3.4)	0.3 (0.0 to 1.8)
Pain at injection site: Severe	0 (0.0 to 1.3)	0 (0.0 to 1.2)	0 (0.0 to 1.2)	0 (0.0 to 1.2)
Pain at injection site: Grade 4	0 (0.0 to 1.3)	0 (0.0 to 1.2)	0 (0.0 to 1.2)	0 (0.0 to 1.2)
Redness: Mild	2.4 (1.0 to 4.9)	3.7 (1.9 to 6.6)	2.0 (0.7 to 4.3)	0.7 (0.1 to 2.4)
Redness: Moderate	1.0 (0.2 to 3.0)	2.0 (0.7 to 4.4)	0.7 (0.1 to 2.4)	0.3 (0.0 to 1.8)
Redness: Severe	0.3 (0.0 to 1.9)	0 (0.0 to 1.2)	0.3 (0.0 to 1.9)	0 (0.0 to 1.2)
Redness: Grade 4	0 (0.0 to 1.3)	0 (0.0 to 1.2)	0 (0.0 to 1.2)	0 (0.0 to 1.2)

Adverse events

Time frame: Local reactions and systemic events (systematic assessment): within 7 days after vaccination. SAEs and other AEs: From Day 1 to 1 month after last vaccination (Up to Month 7). Other adverse events reported at 1% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
Clostridium Difficile Vaccine (Pooled Lots)	41 of 983 (4.2%)	694 of 983 (70.6%)	2 of 983
Placebo	15 of 331 (4.5%)	175 of 331 (52.9%)	2 of 331

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 19 Jan 2023.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Derived from this study: PubMed 37977942Christensen S, Bouguermouh S, Ilangovan K, Pride MW, Webber C, Lockhart SP, Shah R, Kitchin N, Lamberth E, Zhang H, Gao Q, Brock L, Anderson AS, Gruber WC. A phase 3 study evaluating the lot consistency, immunogenicity, safety, and tolerability of a Clostridioides difficile vaccine in healthy adults 65 to 85 years of age. Vaccine. 2023 Dec 7;41(50):7548-7559. doi: 10.1016/j.vaccine.2023.11.003. Epub 2023 Nov 17.
To obtain contact information for a study center near you, click here.Link provided by the sponsor.
Individual participant dataSharing planned: Yes. Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.

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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.

Pfizer CT.gov Call Center study director

Pfizer

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

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing Clostridium difficile vaccine in people with Clostridium Difficile Associated Disease, run by Pfizer at 24 sites in United States.

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 5 inclusion and 19 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 19 Jan 2023. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 24 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. Some participants in this study may receive a placebo. 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 19 Jan 2023). 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?

Geometric Mean Concentrations (GMCs) of Clostridium Difficile Toxin A and Toxin B Specific Neutralizing Antibodies at Month 7 (time frame: At Month 7). The study lists 9 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 NCT03579459, 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 19 Jan 2023.