A lower respiratory infection is an infection in your airways and lungs. It can be due to:

influenza, or the flu
pneumonia
bronchitis
tuberculosis (TB)
Though viruses usually cause lower respiratory infections, they can also be caused by bacteria.

Coughing is the main symptom of a lower respiratory infection. It may produce blood sputum. You may also have a fever, sweating, or chills or experience breathlessness, wheezing, and a tight feeling in your chest.Risk factors for lower respiratory infection include:

the flu
poor air quality or frequent exposure to lung irritants
smoking
a weak immune system
crowded child care settings, which mainly affect infants
asthma
HIV
One of the best preventive measures you can take against lower respiratory infections is to get the flu shot every year. People at high risk of pneumonia can also get a vaccine.