Daily probiotic supplements containing Lactobacillus and Bifidobacterium strains may reduce cold and flu symptoms during winter by 50%, according to a recent study. The probiotics were shown to decrease fever incidence by 73%, runny noses by 59%, and coughing by 62%. Maintaining a healthy immune system through proper nutrition, hygiene, sleep, and temperature control can also help avoid catching flu and other viruses during the colder months. Regular hand washing is particularly important for preventing illness spread.