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

A Prospective Study to Determine the Immunomodulatory Effect of Probiotics on the Immunogenicity of Anti-SARS-CoV-2 Vaccine Recipients Study.

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.

Study Overview

• Status: Completed
• Conditions: COVID-19; Immune Response
• Intervention / Treatment: Dietary supplement: Probiotics; Other: Placebo

Detailed Description

Large-scale clinical trials have demonstrated that COVID-19 vaccines effectively reduce the incidence of COVID-19, as well as the risk of severe disease and mortality. These protective effects are primarily mediated through vaccine-induced immune responses, including both humoral immunity (antibody production) and cellular immunity.

Probiotics are widely recognized for their potential health benefits and are commonly consumed in foods such as yogurt. Emerging evidence suggests that probiotic supplementation may enhance immune responses to vaccination, as demonstrated in studies involving influenza vaccines.

This study is designed to investigate whether oral probiotic supplementation can modulate the immune response to COVID-19 vaccination. The study will evaluate both antibody responses and cellular immune responses following vaccination, and assess whether probiotics can enhance or accelerate the development of vaccine-induced immunity. In addition, the study will explore whether probiotic supplementation may reduce vaccine-related adverse effects.

A total of 140 participants are planned to be enrolled in this study.

• Study Type: Interventional
• Enrollment (Actual): 138
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Taiwan
  • Taipei, Taiwan
    • Taipei Medical University Hospital.

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

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

Exclusion Criteria:

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Probiotic Group; 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; 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.; Other Names: Lactobacillus spp.; Probiotic supplement; Lactic acid bacteria
Placebo Comparator: Placebo Group; 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; 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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

Collaborators and Investigators

• Sponsor: Grape King Bio Ltd.
• Collaborators: Taipei Medical University Hospital

Study record dates

Study Major Dates

• Study Start (Actual): October 13, 2021
• Primary Completion (Actual): March 31, 2022
• Study Completion (Actual): March 31, 2022

Study Registration Dates

• First Submitted: May 21, 2026
• First Submitted That Met QC Criteria: May 21, 2026
• First Posted (Actual): May 28, 2026

Study Record Updates

• Last Update Posted (Actual): June 3, 2026
• Last Update Submitted That Met QC Criteria: May 31, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Respiratory Tract Infections; Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases; Lung Diseases; Pneumonia, Viral; Pneumonia; Coronavirus Infections; Coronaviridae Infections; Nidovirales Infections; COVID-19; Dietary Supplements; Food; Diet, Food, and Nutrition; Physiological Phenomena; Food and Beverages; Probiotics; Lacteol
• Other Study ID Numbers: N202109037

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No