Upper Respiratory Tract InfectionsNCT07908797
Probiotic Trial for URTI Prevention in Healthy Adults
A study testing Probiotic Formula in people with Upper Respiratory Tract Infections, run by Harokopio University at 1 site in Greece.
Trial summary
This randomized, double-blind, placebo-controlled clinical trial in generally healthy adults aged 18-65 years will compare the incidence of upper respiratory tract infections (URTIs) over 16 weeks between probiotic supplement and placebo. Read more about this study
- Who is it for?
- Ages 18 to 65 yearsHealthy volunteers can take part
- Conditions the study is for
- Upper Respiratory Tract Infections
- What is being tested?
- Probiotic Formula
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 140 participants
- Where
- 1 siteGreece
- Study dates
- Oct 2026to Apr 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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 18 to 65 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Age 18-65 years inclusive at the time of consent.
- Generally healthy at enrolment, with no active upper respiratory tract infection (URTI) or other acute infection requiring treatment at baseline, as determined by protocol-defined screening procedures and investigator judgement.
- Able and willing to provide valid written informed consent before undertaking any study-specific procedures.
- Willing and able to take the allocated study product daily for 12 weeks, complete online/mobile-based daily URTI surveillance for 16 weeks, complete episode-specific symptom assessments when required, and attend the scheduled baseline, Week 12, and Week 16 assessments.
- Able to read and understand the approved Greek-language study materials, complete the required study questionnaires and monitoring procedures, and provide valid written informed consent.
Who cannot join
- Known or suspected clinically significant immunodeficiency or current use of systemic immunosuppressive therapy that, in the investigator's judgement, could affect participant safety, susceptibility to infection, or interpretation of study outcomes.
- Active URTI or other clinically relevant acute infection at baseline; use of systemic antibacterial antibiotics within 14 days before baseline; or another acute illness that could confound baseline clinical or biomarker assessments.
- Receipt of any influenza, COVID-19, or other systemic vaccination within 14 days before baseline, or ongoing clinically relevant vaccine-related symptoms at baseline.
- Use of prebiotic or probiotic supplements or yeast-based probiotic products within 1 month before baseline.
- Current pregnancy or breastfeeding, or intention to become pregnant during the 16-week study period.
- Known allergy, intolerance, or hypersensitivity to any component or excipient of the study products.
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- Acute, unstable, or uncontrolled chronic disease, or any other clinically significant medical condition that, in the investigator's judgement, could compromise participant safety, materially influence immune or inflammatory outcomes, interfere with assessment of URTI outcomes, or affect adherence to study procedures.
- Current participation in another interventional clinical trial or other research study that could interfere with the intervention or outcome assessment.
- Any medical, cognitive, practical, or other circumstance that, in the investigator's judgement, would prevent reliable completion of study-product administration, mobile monitoring, questionnaires, scheduled visits, or other study procedures, or would preclude provision of valid informed consent.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Greece1 site, 1 recruiting
- Recruiting
Harokopio University
Athens, Attica, 17676
George Moschonis, +306948965499, gmoschi@hua.gr
Theofanis Papadopoulos, +306980562788, fpapadopoulos@hua.gr
About this study
Official title: Effectiveness of a Probiotic Formula in Preventing Upper Respiratory Tract Infections in Healthy Adults: A Double-Blind, Randomized, Placebo-Controlled Trial
This randomized, double-blind, placebo-controlled clinical trial in generally healthy adults aged 18-65 years will compare the incidence of upper respiratory tract infections (URTIs) over 16 weeks between probiotic supplement and placebo.
Read the detailed description
This study will evaluate whether a daily probiotic formula can reduce the occurrence of upper respiratory tract infections (URTIs) in generally healthy men and women aged 18-65 years. A total of 140 participants will be randomly assigned to receive either the probiotic formula or a matching placebo once daily for 12 weeks, followed by a 4-week period without study product.Participants will complete daily mobile-based monitoring for cold and upper respiratory symptoms throughout the 16-week study. The main outcome is the number of clinically confirmed URTI episodes experienced by each participant. The study will also assess symptom severity and duration, medication and antibiotic use, healthcare utilization, days missed from work or study, quality of life, gastrointestinal symptoms, safety and tolerability, as well as changes in oral microbiota and inflammatory biomarkers.
- Conditions
- Upper Respiratory Tract Infections
- Being tested
- Probiotic Formula, Matching placebo
- Keywords
- Probiotics, Common cold, URTI prevention, Respiratory tract infections, Oral microbiota, Inflammatory biomarkers
- Medical subject headings
- Respiratory Tract Infections, Common Cold
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Probiotic FormulaDietary supplement
The probiotic formula provides a total of 1.25 × 10⁹ CFU of live probiotic microorganisms per sachet. Participants will take one sachet once daily at night for 12 consecutive weeks.
Matching placeboDietary supplement
Matching sachet formulation containing no probiotic microorganisms. Participants will take one sachet once daily at night for 12 consecutive weeks.
| Study group | Role | What they receive |
|---|---|---|
| Probiotic Formula | Experimental | Participants will receive the probiotic formula, one sachet once daily for 12 weeks. Receives: Dietary Supplement: Probiotic Formula |
| Placebo | Placebo comparator | Participants will receive a matching placebo sachet, one sachet once daily for 12 weeks. Receives: Dietary Supplement: Matching placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of clinically confirmed upper respiratory tract infection (URTI) episodes per participant
The number of clinically confirmed URTI episodes experienced by each participant during the study.
Measured: 16 weeks (Week 0 to Week 16)
Secondary outcomes (13)
Proportion of participants experiencing clinically confirmed URTI episodes
Proportion of participants experiencing at least 1, at least 2, and at least 3 clinically confirmed URTI episodes during the study period.
Measured: 16 weeks (Week 0 to Week 16)
URTI episode duration and timing
Duration of individual clinically confirmed URTI episodes, cumulative symptomatic days, URTI-free time, and time to first clinically confirmed URTI episode.
Measured: 16 weeks (Week 0 to Week 16)
Predominant symptom-based URTI clinical presentation
Clinical characteristics and treatment outcomes of clinician-confirmed URTI episodes classified according to the prespecified study-specific symptom-domain classification.
Measured: 16 weeks (Week 0 to Week 16)
Sore-throat outcomes during clinically confirmed URTI episodes
Number of clinically confirmed URTI episodes involving sore throat, duration and severity.
Measured: 16 weeks (Week 0 to Week 16)
Medication and healthcare utilisation related to URTI episodes
Use of symptomatic medications, prescribed antibiotics, and healthcare services related to clinically confirmed URTI episodes.
Measured: 16 weeks (Week 0 to Week 16)
Days absent from work or study due to URTI illness
Number of days absent from work or study because of clinically confirmed URTI illness during the study period.
Measured: 16 weeks (Week 0 to Week 16)
Health-related quality of life
Health-related quality of life assessed using the EQ-5D-5L at prespecified study timepoints.
Measured: Baseline (Week 0), Week 12, and Week 16
Gastrointestinal symptoms
Gastrointestinal symptom burden assessed using the 15-item Gastrointestinal Symptom Rating Scale (GSRS).
Measured: Baseline (Week 0), Week 12, and Week 16
Change in oral microbiota composition
Changes in oral microbiota composition and prespecified microbiota features assessed using 16S rRNA gene sequencing of saliva samples collected at baseline and Week 12.
Measured: Baseline (Week 0) to Week 12
Change in systemic inflammatory biomarkers
Changes in systemic inflammatory biomarkers, including high-sensitivity C-reactive protein (hs-CRP) and interleukin-6 (IL-6), assessed using fasting blood samples collected at baseline and Week 12.
Measured: Baseline (Week 0) to Week 12
Adherence to the study intervention
Adherence to the allocated study product assessed during the 12-week intervention using electronic adherence records and corroborated by returned sachet counts at Week 12.
Measured: 12 weeks (Week 0 to Week 12)
Safety and tolerability
Frequency, nature, severity, seriousness, and relationship to the study product of reported adverse events, together with study-product discontinuations attributable to adverse events.
Measured: 16 weeks (Week 0 to Week 16)
Dietary intake and physical activity
Dietary intake and prespecified measures of physical activity, including changes where applicable, assessed over the study period.
Measured: Baseline (Week 0), Week 12, and Week 16
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Nov 2026
- Study startOct 2026 (estimated)
- Primary completionApr 2027 (estimated)
- Study completionApr 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Upper Respiratory Tract InfectionsStudies 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 N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 140 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Harokopio University
- Sponsor type
- University, hospital or other
- Collaborators
- Lallemand Health Solutions
- Responsible party
- Principal investigator, George Moschonis, Harokopio University
- Investigators
- George Moschonis, Principal investigator, Harokopio University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07908797
- Sponsor's protocol ID
- 66/28-04-2026
- Status last verified
- Oct 2026
- First submitted
- 26 Oct 2026
- Last updated
- 2 Nov 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 2 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effectiveness of a Probiotic Formula in Preventing Upper Respiratory Tract Infections in Healthy Adults: A Double-Blind, Randomized, Placebo-Controlled Trial
- ClinicalTrials.gov ID
- NCT07908797
- Acronym / sponsor ID
- 66/28-04-2026
- Conditions
- Upper Respiratory Tract Infections
- Keywords
- Probiotics, Common cold, URTI prevention, Respiratory tract infections, Oral microbiota, Inflammatory biomarkers
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 140 participants (estimated)
- Lead sponsor
- Harokopio UniversityUniversity, hospital or other
- Collaborators
- Lallemand Health Solutions
- Study start
- Oct 2026 (estimated)
- Primary completion
- Apr 2027 (estimated)
- Study completion
- Apr 2027 (estimated)
- First posted
- 2 Nov 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This randomized, double-blind, placebo-controlled clinical trial in generally healthy adults aged 18-65 years will compare the incidence of upper respiratory tract infections (URTIs) over 16 weeks between probiotic supplement and placebo.
Detailed description
This study will evaluate whether a daily probiotic formula can reduce the occurrence of upper respiratory tract infections (URTIs) in generally healthy men and women aged 18-65 years. A total of 140 participants will be randomly assigned to receive either the probiotic formula or a matching placebo once daily for 12 weeks, followed by a 4-week period without study product.Participants will complete daily mobile-based monitoring for cold and upper respiratory symptoms throughout the 16-week study. The main outcome is the number of clinically confirmed URTI episodes experienced by each participant. The study will also assess symptom severity and duration, medication and antibiotic use, healthcare utilization, days missed from work or study, quality of life, gastrointestinal symptoms, safety and tolerability, as well as changes in oral microbiota and inflammatory biomarkers.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Probiotic Formula | Experimental | Dietary Supplement: Probiotic FormulaParticipants will receive the probiotic formula, one sachet once daily for 12 weeks. |
| Placebo | Placebo comparator | Dietary Supplement: Matching placeboParticipants will receive a matching placebo sachet, one sachet once daily for 12 weeks. |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Age 18-65 years inclusive at the time of consent.
- Generally healthy at enrolment, with no active upper respiratory tract infection (URTI) or other acute infection requiring treatment at baseline, as determined by protocol-defined screening procedures and investigator judgement.
- Able and willing to provide valid written informed consent before undertaking any study-specific procedures.
- Willing and able to take the allocated study product daily for 12 weeks, complete online/mobile-based daily URTI surveillance for 16 weeks, complete episode-specific symptom assessments when required, and attend the scheduled baseline, Week 12, and Week 16 assessments.
- Able to read and understand the approved Greek-language study materials, complete the required study questionnaires and monitoring procedures, and provide valid written informed consent.
Key exclusion criteria (9 listed)
- Known or suspected clinically significant immunodeficiency or current use of systemic immunosuppressive therapy that, in the investigator's judgement, could affect participant safety, susceptibility to infection, or interpretation of study outcomes.
- Active URTI or other clinically relevant acute infection at baseline; use of systemic antibacterial antibiotics within 14 days before baseline; or another acute illness that could confound baseline clinical or biomarker assessments.
- Receipt of any influenza, COVID-19, or other systemic vaccination within 14 days before baseline, or ongoing clinically relevant vaccine-related symptoms at baseline.
- Use of prebiotic or probiotic supplements or yeast-based probiotic products within 1 month before baseline.
- Current pregnancy or breastfeeding, or intention to become pregnant during the 16-week study period.
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 |
|---|---|---|
| Probiotic FormulaThe probiotic formula provides a total of 1.25 × 10⁹ CFU of live probiotic microorganisms per sachet. Participants will take one sachet once daily at night for 12 consecutive weeks. | Dietary supplement | Probiotic Formula |
| Matching placeboMatching sachet formulation containing no probiotic microorganisms. Participants will take one sachet once daily at night for 12 consecutive weeks. | Dietary supplement | Placebo |
Primary outcome
Number of clinically confirmed upper respiratory tract infection (URTI) episodes per participant
Time frame: 16 weeks (Week 0 to Week 16)
The number of clinically confirmed URTI episodes experienced by each participant during the study.
13 secondary outcomes
Proportion of participants experiencing clinically confirmed URTI episodes
Time frame: 16 weeks (Week 0 to Week 16)
URTI episode duration and timing
Time frame: 16 weeks (Week 0 to Week 16)
Predominant symptom-based URTI clinical presentation
Time frame: 16 weeks (Week 0 to Week 16)
Sore-throat outcomes during clinically confirmed URTI episodes
Time frame: 16 weeks (Week 0 to Week 16)
Medication and healthcare utilisation related to URTI episodes
Time frame: 16 weeks (Week 0 to Week 16)
Days absent from work or study due to URTI illness
Time frame: 16 weeks (Week 0 to Week 16)
Health-related quality of life
Time frame: Baseline (Week 0), Week 12, and Week 16
Gastrointestinal symptoms
Time frame: Baseline (Week 0), Week 12, and Week 16
Change in oral microbiota composition
Time frame: Baseline (Week 0) to Week 12
Change in systemic inflammatory biomarkers
Time frame: Baseline (Week 0) to Week 12
Adherence to the study intervention
Time frame: 12 weeks (Week 0 to Week 12)
Safety and tolerability
Time frame: 16 weeks (Week 0 to Week 16)
Dietary intake and physical activity
Time frame: Baseline (Week 0), Week 12, and Week 16
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 2 Nov 2026.
- Individual participant dataSharing planned: No
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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.
George Moschonis principal investigator
Harokopio University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Probiotic Formula in people with Upper Respiratory Tract Infections, run by Harokopio University at 1 site in Greece.
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 9 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: looking for participants now, as of the sponsor's last update on 2 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Greece. 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.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact George Moschonis (+306948965499, gmoschi@hua.gr), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number of clinically confirmed upper respiratory tract infection (URTI) episodes per participant (time frame: 16 weeks (Week 0 to Week 16)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 Nov 2026.