Upper Respiratory Tract Infections Viral upper respiratory tract infections (URIs), better known as the common cold, affect most people occasionally. Adults tend to get two to four colds a year, and children can get eight to 10 colds per year. While the symptoms make you feel bad, the infections are not serious and normally end within a few days. Bacterial URIs (either sinusitis or bronchitis) can also develop. It can be difficult, even for doctors, to tell the difference between a viral and bacterial URI. Many factors, including the duration and severity of symptoms and any underlying respiratory problems, need to be considered before antibiotics are prescribed. A viral infection can also weaken a person’s defenses, setting the stage for a secondary bacterial infection. Antibiotics provide relief for a bacterial infection, whereas viral URIs do not respond to antibiotics.