Transmission and Spread of Respiratory Infections

Infected respiratory droplets and particles are the leading cause of infection transmission and spread. You naturally produce fluids in the form of particles or droplets while coughing, sneezing, exhaling, and talking. People with respiratory infections do as well. The only difference is their droplets contain viruses and infectious microorganisms, like bacteria. Coughs or sneezes produce the most amount of respiratory droplets compared to talking or exhaling.

Size Matters

Your nasal cavity contains fine hairs that filter out particles and block them from reaching your airways or lungs. The larger particles are easier to filter out. However, the smaller particles are more likely to make it through your nasal cavity to your airways or lungs, resulting in infection. Coughing or sneezing produces smaller respiratory droplets, while talking produces larger particles or droplets. The size of infectious droplets is not the only variable for infections; the number of infectious particles also contributes to the spread of infections. For instance, more particles and droplets increase your risk for infection.


Airborne contact is how some infections spread. The air we breathe contains particles. When an infected person coughs, sneezes, or even speaks, they produce thousands of infected respiratory droplets that become airborne and eventually inhaled. 

Direct Contact

Direct contact is another way that viral and bacterial infections spread. As its name suggests, it happens when you have direct physical contact with an infected person. For instance, touching and kissing are both ways that infections spread.

Indirect Contact

Indirect contact is another way respiratory infections spread. Unlike direct contact, you don’t need to have contact with an infected person for indirect contact. On the contrary, indirect contact happens when you come into contact with a contaminated object. Often, this occurs when you touch toys and surfaces that have infectious particles and droplets.