To determine if prophylactic supplementation with B. lactis HN019 reduces the risk of developing physician- and laboratory-confirmed influenza infection at any time during the 12-week supplementation period.

Inclusion Criteria:

• Healthy free-living men and women aged 18 to 60 years
• Body mass index between 18.5 and 29.9 kg/m2 (encompasses normal weight and overweight)
• Subject owns a refrigerator and is willing to keep study product refrigerated at all times
• Ability of the participant (in the investigator's opinion) to comprehend the full nature and purpose of the study, including possible risks and side effects
• Consent to the study and willing to comply with study product and methods

Exclusion Criteria:

• Influenza vaccination in last 6 months, or any other vaccination in previous 15 days
• Clinically significant underlying systemic illness that may preclude the subject's ability to complete the trial
• Chronic nasal, laryngeal, pleural, or respiratory condition that could mimic or obscure symptoms of influenza (e.g. chronic allergic rhinitis, asthma, COPD, as determined by medical history and baseline physical examination)
• Chronic use of medication(s) that could suppress or prevent flu-like symptoms (eg, antihistamines, cough medicines; echinacea, high-dose vitamin C)
• Use of medication(s) within the previous 3 months that affect immune response (eg, antibiotics)
• Contraindication to dairy products or any other substance in the study product (eg, lactose intolerance)
• History of alcohol, drug, or medication abuse
• Pregnant or lactating female, or pregnancy planned during study period
• Daily consumption of probiotics, prebiotics, fermented milk, and/or yogurt within 3 months of screening
• Participation in another study with any investigational product within 3 months of screening
• Investigator believes that the participant may be uncooperative and/or noncompliant, and should therefore not participate in the study