The Answer
Isolation is keeping sick people separated from others that are healthy.
Quarantine is keeping well people separated from others in cases where they might have come into contact with those who are sick.
Important Note: Please follow the direction of your local health authorities when instructed to self-isolate or go into quarantine. This post concerns how the definitions of the words differ. Evidence shows that officials may be using the words in ways that are inconsistent with those definitions.
Amid the expanding COVID-19 pandemic, we are hearing a lot about quarantines and isolation. How do the meanings of these words differ from each other?
The US Department of Health and Human Services defines each in the following way.
Isolation is used to separate ill persons who have a communicable disease from those who are healthy. Isolation restricts the movement of ill persons to help stop the spread of certain diseases. For example, hospitals use isolation for patients with infectious tuberculosis.
Quarantine is used to separate and restrict the movement of well persons who may have been exposed to a communicable disease to see if they become ill. These people may have been exposed to a disease and do not know it, or they may have the disease but do not show symptoms. Quarantine can also help limit the spread of communicable disease.
So, according to this definition – isolation is for those who are already sick and quarantine is to protect the public from someone that is well but may have been exposed to sickness.
How are these phrases being used?
The Irish Health Service has a statement about self-isolation and self-quarantine. Their descriptions mirror the HHS definitions above, self-isolation for those that are sick and self-quarantine for those that might have had some contact.
The Government of Canada is urging Canadians to return home as soon as possible. According to the government’s own website travelers are advised to “Self-isolate for 14 days after [their] return from travel outside of Canada.”. This is advice for anyone that is returning, not people who are showing symptoms. That definition of self-isolate is inconsistent with the one noted above and it feels like they should be telling people to self-quarantine.
To make things even more confusing, when you follow the link they share about self-isolation the first thing you see is the title “How to isolate at home when you have COVID-19”.
Another example is Public Health, New Zealand who also seems to be using self-isolation to describe a well person limiting contact with other people in case they have been exposed. It seems like they should be describing self-quarantine instead.
What should we do?
As you can see from these few brief examples, it’s very easy to be confused about what to do. It is best to look at the details of what the health authorities are recommending rather than trying to parse the words they are using.
In this humble author’s opinion, words matter. In a time of crisis, they matter more than ever. Governments and health officials should choose their words very carefully. Careless word use creates confusion, and confusion will make things worse.