Alpha, Delta, Omicron: With newer COVID variants, study reveals how symptoms continue to change

The respiratory system is classified into two main parts: Upper and lower respiratory systems.

The upper respiratory tract consists of the nose, nasal cavity and the pharynx, whereas the lower respiratory tract comprises larynx, trachea, bronchi and the lungs.

That said, an infection of the upper respiratory tract often includes the common cold, tonsillitis, a sinus infection, laryngitis and the flu, which cause mild symptoms such as a sore throat, runny nose, sneezing, headache, muscle pain, etc.

A lower respiratory tract infection on the other hand leads to illnesses such as bronchitis, pneumonia, bronchiolitis, tuberculosis and sometimes even the flu.

The SARs-COV-2 virus has also been identified to cause infections of both upper and lower respiratory tract, depending on the kind of COVID-19 variant one gets infected with.

While with the Delta, the infection of the lower respiratory tract was more prevalent, with Omicron, most people develop upper respiratory infection.