Break the Chain

There is a specific chain of events that must happen for an infection, in this case coronavirus, to spread from an infected person to another person. This chain creates many opportunities to prevent the spread of infection, but to effectively stop this process, we need to leverage as many of those opportunities as possible. Below is a diagram of the chain, and in bold you can see where our opportunities are. I encourage everyone to participate in as many ways as possible to help break the chain.

Infected person

It all starts here.

The goal here is to identify infected people as soon as possible.

But, there are two main barriers:

Asymptomatic patients or a long pre-symptomatic period (time between infection and first symptoms when person could still be contagious)

Testing limitations and delays – This is improving, but rapid, accurate, point-of-care testing is still not readily available

Robust contact tracing would help identify asymptomatic and pre-symptomatic carriers

Widespread screening could also find asymptomatic and pre-symptomatic people (this is what is being done for professional sports)

Portal of Exit

            Coronavirus is primarily spread through droplets produced by coughing, sneezing, talking, etc. 

Many illnesses cause these symptoms as a means of increasing the spread from the current host to others.  This is why respiratory illnesses are typically the most contagious.

Transmission

The primary means of transmission for coronavirus are direct droplet contact and fomites.

Isolating the infected person, quickly and properly, is the most effective way of eliminating transmission.

If an infected person (possibly without symptoms) is not isolated, then social distancing and face masks are the next line of defense that would prevent droplets of an infected person from directly contacting another person.

Fomites are surfaces that infectious particles can land on, and live on, for a period of time (perhaps hours to days).  Consistent sanitation of commonly touched surfaces can help reduce transmission.  Hand washing of the infected person, and use of face masks by the infected person, can limit fomite transmission (by reducing the number of infected droplets on surfaces), as well.

Portal of Entry

Coronavirus enters the body through mucous membranes – specifically mouth, nose and eyes. 

Hand washing and keeping your hands away from your face can prevent viral contact with mucous membranes.

Anyone who needs to care for a known-infected person should wear full protective equipment, like a medical mask, face shield, gloves, etc.  N95 masks are preferred in certain situations.

Non-specific, or innate, immunity is a defense system that can prevent many infections that we encounter.  For example, skin, and snot protect us from many infections, and fever helps destroy or inhibit many, as well.  And, we have some general immune cells that help fight infections, regardless of specific antibodies not being present.  This type of immunity may be improved through healthy lifestyle, such as exercise and good nutrition.

Specific, or antibody-based, immunity is our final line of defense.  When exposed to a particular pathogen, our body can create specific antibodies to fight that particular agent.  Our body then stores these antibodies, so that they can be rapidly reproduced when our body encounters the same infection later.  This is why we only get many infections once, and this is the basis of immunization.

Newly Infected Person

If we get here, then the chain has not been effectively broken, and the process starts again.