"Self-isolation" vs. "self-quarantine". What's the difference?

I have been asked these questions, including the question in the title of this post. I thought it would be useful to share the answers, here.

How do “self-isolation” and “self-quarantine” differ? 

The short answer is “quarantine” is for anyone who does not show symptoms but may have been exposed to a contagious diseases; whereas, “isolation” is for anyone already infected or likely to be infected due to an exposure. Both are done to prevent transmission of the disease to others.

The recommended definitions for “isolation” and “quarantine” in the Model Public Health Act (that is not law unless it is adopted by a state legislature or a form of it) may have been adopted by any state in their public health laws. Keep in mind, every state has their own public health law, these are just recommended standard definitions, not law.

(30) “Isolate,” “Isolated,” or “Isolation” means the physical separation and confinement of an individual or groups of individuals who are infected or reasonably believed to be infected with a contagious or possibly contagious disease from non-isolated individuals, to prevent or limit the transmission of the disease to non-isolated individuals.

(53) “Quarantine” means the physical separation and confinement of an individual or groups of individuals, who are or may have been exposed to a contagious or possibly contagious disease and who do not show signs or symptoms of a contagious disease, from non-quarantined individuals, to prevent or limit the transmission of the disease to non-quarantined individuals.

The World Health Organization also similarly defines these terms in the International Health Regulations (IHR), but includes articles and animals as well as humans, unlike the Model Act definitions:

“quarantine” means the restriction of activities and/or separation from others of suspect persons who are not ill or of suspect baggage, containers, conveyances or goods in such a manner as to prevent  the possible spread of infection or contamination;

“isolation” means separation of ill or contaminated persons or affected baggage, containers, conveyances, goods or postal parcels from others in such a manner as to prevent the spread of infection or contamination;

·  What do we know about the risk of people going out once they are told to self-isolate? How likely are they to spread it? 

Our system of quarantine/isolation has always been based on the concept of the “social compact” that means the government gives you the maximum amount of freedom to protect public health in exchange for your agreement to restrict/burden your own freedom to the degree required to do that. So ethical people agree to this “social compact”. The problem occurs when people do not keep that agreement, that happens more often than you would think. For example. Tuberculosis patients agree to come in everyday for antibiotic treatment in exchange for going about their day with complete freedom of movement. However, TB patients often do not show up for their antibiotics especially if they are drug addicts, so eventually, the court will agree to an order after giving them significant due process to comply with the “social compact”. The consequences of someone with COVID-19 violating their ”social compact” has high consequences. This may indicate a higher likelihood of court ordered isolations or quarantines because when balanced against the harm, the burden on the individual will be reasonable to prevent that harm. But our constitutional due process requires that we give a reliable patient the maximum freedom to self-isolate in their home with only the minimum amount of confinement necessary to protect the public health.

The infection rate is about the same as flu and SARS although with different consequences.

·  Do public health officials have any way of keeping up with all of the people who have been asked to self-isolate or quarantine? Is a court order, required?

Canada did a remarkable job of self-isolation and self-quarantine of people with symptoms or exposure to SARS in 2003-4, when they identified these travelers and sent them home and asked them to call in each day with a reading of their temperature. They communicated via telephone or Skype. This is human resource intensive, but they allowed people to enter their temperature online each day, reducing the human resource burden near the end of the cycle of SARS. We should be able to do that. If someone missed calling in, a human followed up with a phone call or a visit.

The U.S. is asking its citizens to honor the social compact and use social distancing even if it is inconvenient, both for the safety of the individual and the safety of others. The U.S. or its states may even ask for self-isolation or self-quarantine of particular individuals, again asking them to honor the social compact. We can do it.