The study aims to investigate the effect of the level of probiotic K12 content on enhancing children's immunity and reducing the frequency of their occurrence of diseases such as pharyngitis, tonsillitis, and rhinitis
| ISRCTN | ISRCTN33436648 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN33436648 |
| Sponsor | Baoxing Center for Disease Control and Prevention |
| Funder | Wecare Probiotics (Suzhou) Co., Ltd. |
- Submission date
- 02/03/2026
- Registration date
- 12/05/2026
- Last edited
- 01/09/2026
- Recruitment status
- No longer recruiting
- Overall study status
- Completed
- Condition category
- Respiratory
Plain English summary of protocol
Not provided at time of registration
Contact information
Scientific, Public, Principal investigator
No. 1617, Riyue Avenue, Qingyang District
Chengdu
610091
China
| Phone | +86 (0)13981782973 |
|---|---|
| kechen@uestc.edu.cn |
Study information
| Primary study design | Interventional |
|---|---|
| Allocation | Randomized controlled trial |
| Masking | Blinded (masking used) |
| Control | Placebo |
| Assignment | Parallel |
| Purpose | Prevention |
| Scientific title | The safety and efficacy of Streptococcus salivarius subspecies thermophilus K12 in improving recurrent respiratory tract infections in children: a randomized, double-blind, placebo-controlled trial |
| Study objectives | To evaluate the safety and effectiveness of K12 in children to improve the symptoms of ear, nose and throat (ENT)/upper respiratory tract infections (URTIs). |
| Ethics approval(s) |
Approved 13/01/2026, Ethics Review Committee of Baoxing Center for Disease Control and Prevention (No. 1, Zhongling Avenue, Baosheng County, Anya City, Sichuan Province, Zhongling, 625700, China; +86 (0)835-6822027; 263662086@qq.com), ref: Research Ethics Review 2026 (01) |
| Health condition(s) or problem(s) studied | Recurrent respiratory tract infections in children |
| Intervention | Current interventions as of 30/06/2026: Participants were randomised using SPSS to either a low dose of probiotic bacteria (100 million CFP), a high dose of probiotic bacteria (5 billion CFP) or a placebo tablet one time per day (sterile powder, same derivative). The intervention period was 12 weeks, and saliva was taken after the intervention, after 6 weeks of intervention and at the end of the intervention, and the sample inspection was carried out during the 13 weeks of follow-up. At Week 0, Week 3, Week 6, Week 9, Week 12 and Week 16, questionnaires were completed and during the intervention the patients were asked to take the corresponding product every day and record adverse reactions and compliance. During the study, the doctor recorded the incidence of upper respiratory tract infections, including the number of attacks, symptoms, and duration. By analyzing the statistics and analysis of these data, the improvement of the recurrence rate of the upper respiratory tract infection was calculated. In addition, the Canadian Acute Respiratory and Flu Scale (CARIFs) was used to quantify the incidence of upper respiratory infections in participants. _____ Previous interventions as of 29/06/2026: Participants were randomised using SPSS to either a low dose of probiotic bacteria (100 million CFU), a high dose of probiotic bacteria (500 million CFU) or a placebo tablet one time per day (sterile powder, same derivative). The intervention period was 12 weeks, and saliva was taken after the intervention, after 6 weeks of intervention and at the end of the intervention, and the sample inspection was carried out during the 13 weeks of follow-up. At Week 0, Week 3, Week 6, Week 9, Week 12 and Week 16, questionnaires were completed and during the intervention the patients were asked to take the corresponding product every day and record adverse reactions and compliance. During the study, the doctor recorded the incidence of upper respiratory tract infections, including the number of attacks, symptoms, and duration. By analyzing the statistics and analysis of these data, the improvement of the recurrence rate of the upper respiratory tract infection was calculated. In addition, the Canadian Acute Respiratory and Flu Scale (CARIFs) was used to quantify the incidence of upper respiratory infections in participants. _____ Previous interventions: Participants were randomised using SPSS to either a low dose of probiotic bacteria (100 million CFP), a high dose of probiotic bacteria (5 billion CFP) or a placebo tablet one time per day (sterile powder, same derivative). The intervention period was 12 weeks, and saliva was taken after the intervention, after 6 weeks of intervention and at the end of the intervention, and the sample inspection was carried out during the 13 weeks of follow-up. At Week 0, Week 3, Week 6, Week 9, Week 12 and Week 16, questionnaires were completed and during the intervention the patients were asked to take the corresponding product every day and record adverse reactions and compliance. During the study, the doctor recorded the incidence of upper respiratory tract infections, including the number of attacks, symptoms, and duration. By analyzing the statistics and analysis of these data, the improvement of the recurrence rate of the upper respiratory tract infection was calculated. In addition, the Canadian Acute Respiratory and Flu Scale (CARIFs) was used to quantify the incidence of upper respiratory infections in participants. |
| Intervention type | Supplement |
| Primary outcome measure(s) |
|
| Key secondary outcome measure(s) | |
| Completion date | 30/08/2026 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Mixed |
| Lower age limit | 3 Years |
| Upper age limit | 18 Years |
| Sex | All |
| Target sample size at registration | 180 |
| Total final enrolment | 179 |
| Key inclusion criteria | 1. Consistent with the diagnostic criteria for the clinical and clinical treatment of recurrent respiratory tract infection (2022) 2. Aged 3 to 18 years old 3. During the study (screening to follow-up), no probiotics, probiotics and cogenic milk products were used in this study 4. Agree to sample saliva and other biological samples during this study 5. The guardian of the child is aware of the study and signed the informed consent form |
| Key exclusion criteria | 1. In the first month of the group, the children of the same strain were studied 2. Treatments such as antibiotics, disinfectants, antifungal drugs, glucocorticosteroids and other treatments were accepted within 7 days of entering the group 3. Children who need hospitalization for malnutrition 4. Known to be sensitive, intolerant or allergic to any research product (including lactose, milk protein, etc) 5. Use any experimental drugs for the first 3 months of screening and participate in other clinical studies 6. Diagnosis of basic disease, such as above-moderate anemia, ricular disease, chronic diarrhea, stable diseases, congenital cardiovascular malformity, various causes of severe malnutrition, secondary immunodeficiency, kidney disease, cerebral palsy, and long-term immune inhibitors 7. Congenital immunodeficiency diseases (such as the common immunodeficiency disease in China): the X chain does not have hepatitis C, X chain high immunoglobulinemia, eczema, necrosis, or thrombocytopenia immunodeficiency syndrome 8. In the first 3 months of the group, took drugs that affected immune function (immunosuppressant, immunoenhancers, hormones, blood products, Chinese medicine, etc) 9. The researchers judge that there is a discomfort involved in compliance or safety 10. Vaccination or other active vaccines in the first 4 weeks of screening |
| Date of first enrolment | 13/03/2026 |
| Date of final enrolment | 15/05/2026 |
Locations
Countries of recruitment
- China
Study participating centres
Results and Publications
| Individual participant data (IPD) Intention to share | Yes |
|---|---|
| IPD sharing plan | The datasets generated and/or analysed during the current study will be stored in a publicly available repository, the Clinical Trial Management Public platform (http://www.medresman.org.cn/login.aspx). Upload original data within 6 months after the end of the trial. |
Editorial Notes
01/09/2026: The following changes were made to the study record:
1. The scientific title was changed from 'The safety and efficacy of Streptococcus salivary subspecies K12 in improving recurrent respiratory tract infections in children: a randomized, double-blind, placebo-controlled trial' to 'The safety and efficacy of Streptococcus salivarius subspecies thermophilus K12 in improving recurrent respiratory tract infections in children: a randomized, double-blind, placebo-controlled trial'.
2. The date of first enrolment was changed from 31/03/2026 to 13/03/2026.
3. The date of final enrolment was changed from 31/12/2026 to 15/05/2026.
4. The completion date was changed from 12/01/2027 to 30/08/2026.
5. Final enrolment number added.
30/06/2026: The following changes were made to the study record:
1. The scientific title was changed from "The safety and efficacy of Streptococcus salivarius subspecies thermophilus K12 in improving recurrent respiratory tract infections in children: a randomized, double-blind, placebo-controlled trial" to "The safety and efficacy of Streptococcus salivary subspecies K12 in improving recurrent respiratory tract infections in children: a randomized, double-blind, placebo-controlled trial".
2. The interventions were changed.
3. The Intervention Type "Supplement" was changed to "Drug" and Phase "Phase I" and Drug/device/biological/vaccine name(s) "Streptococcus salivary subspecies K12" were added.
29/06/2026: The following changes were made:
1. The scientific title was changed from "The safety and efficacy of Streptococcus salivary subspecies K12 in improving recurrent respiratory tract infections in children: a randomized, double-blind, placebo-controlled trial".
2. Intervention Type "Drug" was changed to "Supplement, which removed Phase "Phase I" and Drug/device/biological/vaccine name(s) "Streptococcus salivary subspecies K12".
3. Interventions were updated.
02/03/2026: Study's existence confirmed by the Ethics Review Committee of Baoxing Center for Disease Control and Prevention.
