Immunomodulatory Effect of Probiotics on the Immunogenicity of Anti-SARS-CoV-2 Vaccines

NCT07610512 | Completed

• 1 other identifier: N202109037
• Study Type: interventional
• Target: 138
• Locations: 1 country
• Sites: 1

Brief Summary

This study aims to evaluate whether oral probiotic supplementation can modulate the immune response induced by COVID-19 vaccination. Specifically, the study will assess the effects of probiotics on vaccine-induced antibody responses and cellular immune responses, and explore whether probiotics may enhance or accelerate immunity and reduce vaccine-related adverse effects. A total of 140 participants are planned to be enrolled.

Conditions

COVID-19; Immune Response

Outcome Measures

Primary Outcomes (2)

• SARS-CoV-2 spike protein-specific IgG antibody level

  Change in SARS-CoV-2 spike protein-specific IgG antibody levels following COVID-19 vaccination between probiotic and placebo groups.

  Baseline (Day 0-7 before vaccination), Day 14 (±4 days), and Day 28 (±4 days) after first dose of BNT162b2 vaccination

• SARS-CoV-2-specific T cell immune response at Day 14 after vaccination.

  Assessment of vaccine-induced cellular immune response measured by antigen-specific T cell activation between probiotic and placebo groups.

  Baseline and Day 14 (±4 days) after vaccination

Study Arms (2)

Probiotic Group

EXPERIMENTAL

Participants will receive oral probiotic capsules containing Lactobacillus spp. once daily for 4-5 weeks following COVID-19 vaccination. The intervention is administered to evaluate the immunomodulatory effects of probiotics on vaccine-induced humoral and cellular immune responses.

Dietary Supplement: Probiotics

Placebo Group

PLACEBO COMPARATOR

Participants will receive matching placebo capsules containing microcrystalline cellulose once daily for 4-5 weeks following COVID-19 vaccination. The placebo is identical in appearance, packaging, and administration schedule to the probiotic capsules.

Other: Placebo

Interventions

Probiotics DIETARY_SUPPLEMENT

Oral probiotic capsules containing Lactobacillus spp. administered once daily for 4-5 weeks following COVID-19 vaccination to evaluate immunomodulatory effects on vaccine-induced immune responses.

Also known as: Lactobacillus spp., Probiotic supplement, Lactic acid bacteria

Probiotic Group

Placebo OTHER

Matching placebo capsules containing microcrystalline cellulose administered once daily for 4-5 weeks following COVID-19 vaccination. The placebo is identical in appearance, packaging, and schedule to the probiotic capsules.

Placebo Group

Eligibility Criteria

• Age: 20 Years - 65 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Male or female subject ≥ 20 to ≤ 65 years of age at the time signing informed consent form.
• Body weight ≥50 kgs
• Must be scheduling to receive a BNT162b2 mRNA COVID-19 vaccine
• Being able to comply with the study protocol
• Being able to independently provide written informed consent

You may not qualify if:

• Taking antibiotic at enrollment
• Taking immunomodulatory (e.g., steroid) or anti-histamine drugs
• Took pre- or probiotics within the past 30 days
• Being to expected to take other probiotic supplement during the study period
• Being expected to take antibiotic during the study period
• A history of hypersensitivity or severe allergic reaction to any components of the probiotics or placebo supplement
• Pregnant or breastfeeding
• Having a severe immunocompromised disorder (e.g. HIV infection)
• Solid organ or bone marrow transplant recipients
• Major gastrointestinal surgery within 3 months before enrollment
• Having severe active gastrointestinal conditions, including inflammatory bowel disease or diverticulitis
• No self-reported symptoms of an upper airway infection with the past 2 weeks
• A history of SARS-CoV-2 infection
• Previously participated in investigational study involving SARS-CoV-2 vaccines or therapies

Sponsors & Collaborators

• Grape King Bio Ltd.: lead
• Taipei Medical University Hospital: collaborator

Study Sites (1)

Taipei Medical University Hospital.

Taipei, Taiwan

Location

MeSH Terms

Conditions

COVID-19

Interventions

Probiotics; Lacteol

Condition Hierarchy (Ancestors)

Pneumonia, Viral; Pneumonia; Respiratory Tract Infections; Infections; Virus Diseases; Coronavirus Infections; Coronaviridae Infections; Nidovirales Infections; RNA Virus Infections; Lung Diseases; Respiratory Tract Diseases

Intervention Hierarchy (Ancestors)

Dietary Supplements; Food; Diet, Food, and Nutrition; Physiological Phenomena; Food and Beverages

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Masking Details: This is a single-blind (participant-blinded) study. Participants will be randomized to receive either probiotic capsules or matching placebo capsules. The placebo capsules contain microcrystalline cellulose and are identical in appearance, packaging, and administration schedule to the probiotic capsules. Participants will be blinded to treatment assignment, while investigators and study staff will not be blinded.
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: May 21, 2026
• First Posted: May 28, 2026
• Study Start: October 13, 2021
• Primary Completion: March 31, 2022
• Study Completion: March 31, 2022
• Last Updated: June 3, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will not share

Locations

TW (1)