What happens in our body when we encounter and fight off a virus like the flu, SARS-CoV-2 or RSV?
They spread from person to person through respiratory droplets when someone coughs, sneezes, or talks and can cause death in serious cases.
- They spread from person to person through respiratory droplets when someone coughs, sneezes, or talks and can cause death in serious cases.
- But what happens in our body when we first encounter these viruses?
First line of defence
- When we encounter respiratory viruses, the first line of defence is the physical and chemical barriers in our nose, upper airways, and lungs.
- Our defence also includes our behaviours such as coughing or sneezing.
Patrolling for potential invaders
- The cells of innate immunity act like a patrol system, searching for any invaders.
- These innate cells patrol almost every part of our body, from our skin to our nose, lungs and even internal organs.
- In the meantime, natural killer cells, aptly named, attack infected cells, and stop viruses from multiplying and invading our body further.
- At this stage, our immune system is fighting a war against viruses and the result can cause inflammation, fevers, coughs and congestion.
Launching a specific attack
- As the innate immune response begins, another branch of the immune system called the adaptive immune system is activated.
- The adaptive immune system is more specific than the innate immune system, and it decides on the correct tools and strategy to fight off the viral invaders.
- B cells produce antibodies, which are proteins that can bind to viruses, neutralise them, and mark them for destruction by other immune cells.
- B cells are a critical part of memory in our immune system.
Neutralising the threat
- As the infection subsides, symptoms gradually improve, and we begin to feel better and to recover.
- Some respiratory viruses, like rhinoviruses which cause the common cold, may cause relatively mild symptoms and a quick recovery.
- Others, like the flu, SARS-CoV-2 or severe cases of RSV, may lead to more severe symptoms and a longer recovery time.