The primary objective of this study is to evaluate if Broncho-Vaxom® given to high risk infants for 10 days, monthly, for two consecutive years can increase time to occurrence of the first episode of wheezing lower respiratory tract illness (WLRI) during a three year observation period off therapy.

This is a five year parallel arm, double-blind, placebo-controlled trial for the prevention of WLRI into the third to seventh year of life (30 to 78 mo inclusive) in young children (6-18 months old) at increased risk for asthma. The trial will be divided into 2 periods. During the initial treatment period (first and second years in the study) participants will receive Broncho- Vaxom® (3.5 mg) or placebo for ten days each month for two consecutive years. This period will allow the observation of key secondary outcomes while participants are receiving therapy. The second period (third through fifth years in the study) will be a three year observation of the time to occurrence of the first WLRI episode (primary outcome) while off study drug along with the secondary outcomes noted above. During both the treatment and observation periods, participants will be managed by study physicians using a rescue algorithm applied in the PEAK trial commensurate with the NAEPP Expert Panel Report (EPR) III guidelines.

Inclusion Criteria:

• Adequate completion of informed consent process with written documentation. The participant's legally acceptable representative must have provided the appropriate written informed consent. Assent forms will not be used due to the age of the participant population; however, for procedures later in the study when participants are older, age appropriate assent will be obtained, if required by local Institutional Review Board (IRB).
• Age: 6-18 months of age inclusive at randomization which means 5 to 17 months of age inclusive on entry into the one month run-in period. At least half of all enrolled children will be between 6 and 12 months of age at randomization.
• Participants will meet at least one of the following criteria, which have been associated with an increased risk of wheezing respiratory illnesses and asthma: a) Parental history of asthma -or- b) Physician-diagnosed atopic dermatitis in the participant - or- c) Physician-diagnosed asthma in a blood sibling aged 4 years or more.
• Participants may be either male or female.
• Participants will have at least one parent/guardian who can communicate with the study staff to allow assessment of study outcomes. All study materials used by parent/guardian will be made available in English and in Spanish. The child's parent/guardian must have a working direct contact telephone.

Exclusion Criteria:

• Participants may not have had more than two prior WLRI episodes.
• Participants may not have had any SWLRI episodes.
• Participants may not have a physician's diagnosis of asthma.
• Participants may not have a systemic illness (other than allergy) including (but not limited to) recurrent seizures, chronic gastroesophageal reflux (GER) requiring medical treatment, major congenital anomalies, physical and intellectual delay, cerebral palsy, chest surgery, tuberculosis or other chronic infections, primary or secondary immunodeficiency, gastrointestinal malformation or disease or cardiac disorder (except a hemodynamically insignificant atrial septal defect (ASD), ventricular septal defect (VSD) or benign heart murmur).
• Participants may not have been born earlier than 36 weeks of gestation.
• Participants may not have received oxygen for more than 5 days in the neonatal period, or received mechanical ventilation with the exclusion of ventilation during anesthesia for a minor surgical procedure.
• Participants may not have significant neurodevelopmental delay.
• Participants may not be below the 3rd percentile for weight.
• Participants may not have any other chronic lung disease; e.g. chronic lung disease of prematurity (CLDP) or cystic fibrosis.
• Participants may not have a history of any life-threatening respiratory illness that required intubation and mechanical ventilation.
• The participant's family may not be expected to relocate out of study area within 3 years of the initiation of the study.
• Participants may not have received inhaled or systemic corticosteroids for respiratory related illness ever, or for other conditions in the month prior to randomization.
• Participants may not have ever received immunotherapy.
• Participants may not have ever received i.v. gammaglobulins or systemic immunosuppressants.
• Participants may not have received probiotics (Lactobacilli and Bifidobacteria) in medicinal form; (i.e. not including food), regularly for more than 4 months in the 6 to <12 mo age group or 6 months in the 12 to 18 month group prior to enrollment.
• Participant has known sensitivity to any of the study products and any of the ingredients to be administered.
• Participant has previously been randomized in this study. Participants who failed run-in and were not randomized may have study participation terminated and then be re-enrolled for a second run-in period.
• Participant is currently enrolled in or has completed any other investigational device or drug study <30 days prior to screening, or is receiving other investigational agent(s).
• Participant has a significant medical condition(s), anticipated need for major surgery during the study, or any other kind of disorder that may be associated with increased risk to the participant, or may interfere with study assessments, outcomes, or the ability to provide written informed consent or comply with study procedures, in the Investigator's opinion.
• The one month run-in period will be used to evaluate adherence to study drug administration and electronic communication. At randomization the participant must continue to meet enrollment criteria and also have demonstrated 80% adherence to the placebo during treatment period; i.e. 8 out of 10 days and a75% response rate to weekly mobile phone text queries; i.e. 3 out of 4 weekly text queries.
• Ongoing infection (of any organ system) at the time of randomization. This includes infections that are being adequately treated.
• Unable or unlikely to complete study assessments or the study intervention poses undue risk to patient in the opinion of the Investigator.
• Families will speak English and/or Spanish.

Within 6 months of publication, individual participant data will be deposited into the NHLBI BioLINCC data repository (biolincc.nhlbi.nih.gov). The data will be de-identified and accompanied by the data dictionary, study protocol, and case report forms.

Within 6 months of publication and will be available indefinitely.

Anyone who applies to BioLINCC for access