Efficacy and Safety of Oral Lactobacillus Plantarum GUANKE (CGMCC NO.21720) in Enhancement of Antibody Level After SARS-CoV-2 Vaccination (Trial 1)

Efficacy and Safety of Oral Lactobacillus Plantarum GUANKE (CGMCC NO.21720) in Enhancement of Antibody Level After SARS-CoV-2 Vaccination: A Prospective, Randomized, Double-blind, Placebo-Controlled Trial (Trial 1)

Preliminarily explore the effect of oral probiotics in SARS-CoV-2 serum neutralizing antibody titer level and T cell response level (spot formation cell counting).

Provide a reference for determining the appropriate oral regimen. Provide necessary parameters for estimating the sample size of confirmatory clinical trial.

In selected communities or assigned clinical trial institutions, participants who had completed two doses of SARS-CoV-2 vaccination will be invited in this study. Informed consent form will give to potential participants with well explained of trial contents during baseline. Participants who gave their signed informed consent form will be blocked randomized in a 1:1 ratio to intervention group or placebo control group.

Inclusion Criteria:

1. 18 ≤age ≤59 years;
2. Vaccinated with two doses of SARS-CoV-2 vaccine (manufactured by Sino Biopharmaceutical Limited or SINOVAC BIOTECH CO., LTD.) (≥6 months from the time of vaccination).
3. Not vaccinated third dose vaccination;
4. Voluntarily participate in the study with signed informed consent form.

Exclusion criteria:

1. Pregnancy or lactation period;
2. Infected with human immunodeficiency virus (HIV), hepatitis B virus (HBV) or hepatitis C virus (HCV);
3. Plan to vaccinate third dose of SARS-CoV-2 vaccine within 2 months;
4. History of autoimmune diseases (e.g. rheumatoid arthritis, systemic lupus erythematosus, dry syndrome, etc.);
5. Previously infected with SARS-CoV-2 or close contact of SARS-CoV-2 infected individual;
6. Other SARS-CoV-2 vaccination history (not manufactured by Sino Biopharmaceutical Limited or SINOVAC BIOTECH CO., LTD.);
7. End-stage cancer or other terminal diseases with life expectancy <6 month;
8. History of severe cardiovascular and cerebrovascular diseases, such as heart failure, uncontrolled coronary heart disease, cardiomyopathy, uncontrolled arrhythmia,or history of myocardial or cerebral infarction within past six months;
9. Participating in other clinical trials.