Swine flu: isolation and quarantine

As cases continue to accrue in different places we will hear more talk about quarantine and isolation. These are two terms that are frequently confused, which is too bad, because isolation makes sense for influenza and quarantine doesn't. So what do they mean?

What quarantine and isolation have in common is they are both designed to interrupt the transmission of a disease that spreads from person to person. Quarantine is the legally enforceable segregation of people who people who have been or may have been exposed but who aren't (yet) sick. Some people talk about "voluntary quarantines," but it's best to reserve the word for those instances where people are compelled to stay confined. If you took everyone who ha been in Mexico for the past week and involuntarily confined them to their residences or a holding facility, that would be a quarantine. It is a draconian measure and doesn't work for flu and usually makes matters worse. People will intentionally attempt to evade quarantines and in the process spread the disease farther and faster. Historically, the more well off have had an easier time evading quarantines. Their record in interrupting transmission is often poor and they aren't recommended for influenza.

Isolation, on the other hand, is the (usually uncoerced) segregation of people who are already sick. It makes a great deal of sense to prevent people who are definitely shedding virus to mingle with the general public. If you are sick, you should stay home or be in a hospital.

Either isolation or quarantine can be ordered or enforced by state and local authorities, but CDC also has authority to detain, medically examine or conditionally release persons suspected of having certain contagious diseases. To deal with bird flu, the list of contagious diseases was enlarged by Executive Order in 2005 to include "influenza caused by novel or reemergent influenza viruses that are causing, or have the potential to cause, a pandemic." CDC also uses its quarantine authority to monitor disease at ports of entry to the US, and they are doing that now. Under this authority they may detain specific travelers until their health status is ascertained. While no general federal quarantines have been ordered since the 1918 influenza pandemic, and it isn't likely one will be ordered this time at the federal level, there is a moderately large gray area when it comes to temporary detention. Rather than paraphrase, this is how CDC puts it:

Modern quarantine lasts only as long as necessary to protect the public by (1) providing public health care (such as immunization or drug treatment, as required) and (2) ensuring that quarantined persons do not infect others if they have been exposed to a contagious disease.

Modern quarantine is more likely to involve limited numbers of exposed persons in small areas than to involve large numbers of persons in whole neighborhoods or cities.

The duration and scope of quarantine measures would vary, depending on their purpose and what is known about the incubation period (how long it takes for symptoms to develop after exposure) of the disease-causing agent. Examples include:

A few hours for assessment.

Passengers on airplanes, trains or boats believed to be infected with or exposed to a dangerous contagious disease might be delayed for a few hours while health authorities determine the risk they pose to public health. Some passengers may be asked to provide contact information and then released while others who are ill are transported to where they can receive medical attention. There have been a few instances where state and local public health authorities have imposed a brief quarantine at a public gathering, such as a shelter, while investigating if one or more people may be ill.

Enough time to provide preventive treatment or other intervention.

If public health authorities determine that a passenger or passengers on airplanes, trains or boats are sick with a dangerous contagious disease, the other passengers may be quarantined in a designated facility where they may receive preventive treatment and have their health monitored.

For the duration of the incubation period.

If public health officials determine that one or more passenger on airplanes, trains or boats are infected with a contagious disease and that passengers sitting nearby may have had close contact with the infected passenger(s), those at risk might be quarantined in a designated facility, observed for signs of illness and cared for under isolation conditions if they become ill.

Quarantined individuals will be sheltered, fed and cared for at home, in a designated emergency facility or in a specialized hospital, depending on the disease and the available resources. They will also be among the first to receive all available medical interventions to prevent and control disease, including:

Early and rapid diagnostic testing and symptom monitoring.
Early treatment if symptoms appear.

Isolation would last for the period of communicability of the illness, which varies by disease and the availability of specific treatment. Usually it occurs at a hospital or other health care facility or in the person's home. Typically, the ill person will have his or her own room and those who care for him or her will wear protective clothing and take other precautions, depending on the level of personal protection needed for the specific illness.

In most cases, isolation is voluntary; however, federal, state and local governments have the authority to require isolation of sick people to protect the public. (CDC)

CDC has rarely used its quarantine authority, and I don't expect it to use it in this instance. But I wouldn't rule out state and local authorities doing so out of fear.

Fear happens.

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So what is the correct term for the "voluntary quarantine" where someone healthy keeps themselves in their own house?

given the outbreak involved 60% of the town where it started about a month ago in La Gloria, Veracruz Mexico and it is now believed hundreds of students are sick in NYC WHO should goto a phase 5 or 6 condition soon no?

Fear indeed happens - I think I just had an Oh sh1t moment thinking about my 2 yearold son at a daycare at the hospital where me and my wife work - concidering how some of the cases in the US and in Veracruz where very young. He maybe back with grandma daycare for a few weeks.

"voluntary quarantine" - Another/the correct? term would be "voluntary social distancing".

GeorgeT asks: "So what is the correct term for the "voluntary quarantine" where someone healthy keeps themselves in their own house?"

The Politics of Exclusion

Just a quick note--I just got a Tweet from a mom suggesting "swine flu parties" because the U.S. version seems to be a "mild version". Can you speak to the utter insanity of doing this, please?

"Can you speak to the utter insanity of doing this, please?"

Hopefully, revere will answer this but I'll throw in my 2 cents as a layman: that's insane.

The "U.S. version" is simply not known to be a milder version -- until that fact is established it would be crazy to do this. Even if it were a milder version, spreading the virus will still in all likelihood generate severe cases (maybe enough to overload the health care system in places, resulting in fatalities that would otherwise not happen). It also increases the chance of mutation. So, regardless, I would hold off on that form of self-vaccination.

GeorgeT asks: "So what is the correct term for the "voluntary quarantine" where someone healthy keeps themselves in their own house?"

Hiding :)

GeorgeT: hermiting ;)

well, that'd set an interesting initial CFR.

I read that CFR for flu cases severe enough to require hospitalization is typically 5-10% which would be consistent with the reported Mexican CFR.

leaves the question of ratio of mild/severe open of course

revere, isn't it time to make freely available
online all panflu essential papers until this is over ?

Omega.... Wait a couple of days when it starts to take kids here even in low numbers. Email her back and ask her to hold it in honor of the fallen.

I think its in Tennessee now, 12 kids left my sons school today with severe respiratory problems. Might be that they had tests to take too. Couple of hundred more though in NYC and they will call it and close the schools. They always close them too late and reopen too early.

By M. Randolph Kruger (not verified) on 28 Apr 2009 #permalink

Two possible deaths in Los Angeles; males age 33 and 45. Awaiting results of autopsies

They really should hold off autopsying until it's confirmed the two are indeed dead.

Two possible deaths in Los Angeles; males age 33 and 45. Awaiting results of autopsies

They really should hold off autopsying until it's confirmed the two are indeed dead.

OmegaMom: Just a quick note--I just got a Tweet from a mom suggesting "swine flu parties" because the U.S. version seems to be a "mild version". Can you speak to the utter insanity of doing this, please?

Rock #8 nails it. I have nothing much to add. Most people who get seasonal flu aren't any sicker than the cases we've seen so far. But an estimated 40,000 die of it and many who don't are debilitated for months. 55 children were known to have died from plain old seasonal flu. Not really a reasonable thing to do. I understate.

Guys (of all genders), has anyone got a technical answer for GeorgeT's question? Cause we're doing it here in Mexico City, and I too wondered what it was called as I read the original post.

Isolation does little good either since one can be infectious prior to symptoms for 1-3 days. Quarantine may make sense if you can detect it before it spreads, whch is not the case here.

I mean this is the flu, just a new strain of old H1N1. Flu spreads, Live with it, deal with it. It's not clear at this point it is very virulent. And once a new strain of flu spreads, it becomes endemic anyways.

It may be that many folks over the last 2 months have been infected in the US but just shrugged it off as a common cold or seasonal flu. It would seem this should be studied.

"They really should hold off autopsying until it's confirmed the two are indeed dead.
Posted by: Algerine | April 28, 2009 5:34 PM"

Thats true. LOL.

I hope they can provide some racial or ethnic descriptions to help rules out the possibility this flu hits hispanics harder.

I don't know that there's a proper term. You could use:

Voluntary quarantine (people might not understand that means you are NOT sick)

Social distancing

Sheltering in place

Or you could go more colloquial--



hunkering down



By Lisa the GP (not verified) on 28 Apr 2009 #permalink

At least one of the two California deaths appears unrelated to swine flu, and perhaps both are unrelated. The 33 year old from Long Beach was apparently suffering from some sort of lymphoma.

Canadian Press report

AP report

George, Margaret There is a gray area regarding "voluntary quarantine" and no official definition, but if it's voluntary a health law expert I consulted said it wasn't really quarantine but a form of social distancing initiated by an individual.

4 cases in Toronto, all in their 20's, all recovering and only had mild symptoms. Good sign.

And the LA deaths are NOT connected to swine flu.

My understanding was that the incubation period for influenza was from 1-3 days (Heymann, Control of Communicable Diseases Manual). But today I believe I heard that Besser said (or someone quoting him said )that it was anywhere from 3-7 days. A clarification would greatly be appreciated. Thanks.

ira: 2 - 7 days is the usual number for seasonal flu. Earlier it appeared that this virus had a shorter incubation period of 1 - 2 days. The change is apparently on the basis of additional experience with the newly discovered cases where exposure and symptom onset could be more accurately estimated.

serious question: would you allow a kid to go to Disneyland this weekend/next week? We've had a trip planned for a long time and can't reschedule.

By funky chicken (not verified) on 28 Apr 2009 #permalink

funky: If it were me, I'd probably take the trip. That's not a medical opinion, though. At this point there are no known cases in FL, so I'd go for it. Life is a balance. You might strike it differently and plenty might criticize me for it. I can't really defend it, except that as a dad I think that's the way I'd go. Just being honest.

funky chicken: I'm not going to tell you yes or no. I did take my kid out of state last weekend but it was to a state with no reported cases and we drove. We originally were going to San Antonio - glad we didn't because we might have canceled at the last minute. It was just a minor weekend getaway with no locked in costs so no biggie if we bailed.

If you are flying, that would concern me more than Disneyland itself. Are your kids the type who touch everything and put their hands in their mouth/nose/eyes? That greatly affects the risk factor.

If you go, bring hand sanitizer and use it often. Also, disinfecting wipes may be good so you can wipe down stuff though I don't know how effective they are, but they can't hurt. If you want to be paranoid (nothing wrong with that), you can find and buy quality masks - I don't know what's effective and not.

Another consideration is crowd levels. If it was DisneyWorld, I could give you some advise, but not on Disneyland. At Disneyland though, I'd expect weekdays to be less than weekends.

revere: funky is talking Cali not Florida. That affected my answer. Yes, I would be less concerned about Florida but this is Southern CA which has the most non-clustered cases (AFAIK) in the US. But still a drop in the bucket.

Whether it's called 'quarantine' or 'isolation', I *hope* it won't involve locking symptom-free travelers in the same confined quarters with known sick people for ANY length of time! As in on a plane, at the airport, no disembarking allowed, while the toilets overflow, with no masks available, etc.

I seem to remember something like that happening more than once during the SARS outbreak.

The least the mass carriers should do (plane, train, bus, boat, whatever) is have masks on board for each passenger, ready to be distributed if anyone becomes ill enough for the authorities to restrict the rest of the passengers. AND come up with a way in advance for everyone to disembark and spread out as soon as possible. A hanger, tents, porta-potties, whatever, so the sick aren't infecting the healthy.

Not that I trust the authorities to do anything that sensible....I'll be staying off mass transit for the duration.

aiden: this is the key sentence "People will intentionally attempt to evade quarantines and in the process spread the disease farther and faster."

I do think the govt asking people to practice "social distancing" in areas with active infections makes sense - obviously though, it needs a MUCH better term.

I was looking at the death notices in the online newspaper but the newspaper doesn't publish the cause of death. I've seen a lot of people under the age of 60 pass away this week, more than a normal week.

Re: Disneyland
I'm an annual passholder so I go to Disneyland quite often. I went with my children on 4/21 and have plans to go again in May and June.

One thing I ALWAYS do is give my kids Purell after each ride. I also ask them not to hold the railings while we waiting in line. I've seen too many kids picking their noses then touching the hand rails, etc. Disneyland is a lot of fun...but a cesspool of germs (my layperson, germ-a-phob opinion anyway).

Tuesdays and Wednesdays seem to be the least busiest days. Lines were minimal on the 21st.

CBC just reported many patients are left in crowded Canadian emergency rooms while obviously contagious.

What you really need is a Kaizan development of better airflow waiting room areas. Exposure to outdoors would probably be best where there is no winter. This simple solution works in developing world hospitals. To my understanding, developed world hospitals admit patients and then classify them based on severity, but they all wait in the same waiting area. What you really need is separate waiting areas for each individual potentially communicable patient. I think this means a seperate admission area and waiting room (for example, seats spaced 2 metres or whatever apart and "optimal" airflow) for communicable patients. If designed such hospital expansions would employ a lot of unemployed workers, contrary to the opinions of Republicans trying to prevent flu pandemic funding (why?!).

By Phillip Huggan (not verified) on 28 Apr 2009 #permalink

Philip: when I was a child, my doctor had a front entrance for healthy patients and a rear entrance for those who were sick. Never seen anything as good since. It's a shame.

Pork Flu: there are normal ups and downs in the number of obits. For one thing, some papers charge for you to get an obit. Don't read anything into it.

There is a confirmed US death now though. :-(

Hi Everyone,

There is a good article on social distancing at MSNBC -
"Best swine flu strategy: Stay away, everyone
Little-known âsocial distancingâ plans could close schools, gathering spots"


It talks about how it's necessary to take these measures early in an epidemic for them to be effective.

Why they have not yet closed all of the schools in New York City is beyond my comprehension.

They've set up a separate clinic for flu symptoms only in Windsor, Nova Scotia where the first 4 students are. One place I would *not* go without a mask is a waiting room.

Buffy: School closures are a huge decision because we have a country without adequate child care or family sick leave policies. You can do a lot of damage with school closures, so you don't do them lightly. It is a very tricky question. In addition, you have to make sure the children don't just associate with each other or go to the mall. It isn't a no brainer, unfortunately.

Revere: Thanks for your response.

In terms of social structure, a lot more people in Mexico are living with extended family either in the house or nearby than do in the US. I wonder if that affected the decision-making there for officials, in terms of the cost-benefit analysis of closing schools being less burdensome on parents.

It would be nice, though, if social isolation were being addressed a bit more in the news media. Then at least people would be aware that there's a range of tools available even at the individual level for limiting this epidemic....

revere, I agree with your comments about the gravity of making the call to close a school - from the school administration's perspective. They must act on statistics of how many kids have already gotten sick before making the decision - to back them up - to avoid backlash for all the truly significant consequences this would cause (as those you mention).

But I have preached a different perspective to my own grown children about our grandchildren. I'm telling them to keep a sharp eye out, and be the FIRST to keep your kids out of school, away from birthday parties, and day care. It takes a certain amount of courage or determination to be among the first, because psychologically other parents' fear will be raised by your early action, and resent having the dilema of making the decision brought more personally upon them as well, and they will express that resentment and fear towards the first to act, just as we flublog folks have been considered Cassandras all these years.

To wait for the school to close before you keep your kids home, is a decision made way too late.

I'm going to propose a term for "choosing to stay home so you don't catch it."

"Preventive Self-Quarantine," and the acronym "PSQ."

Strictly speaking it's a mis-use of the term "quarantine," however it appears to be the best overall construction because:

The word "preventive" makes it clear that the individual is not sick at the time. There is not a shorter word that is as readily understood for this purpose.

The word "self-" makes it clear that it is a voluntary measure. "Self" is preferable to "voluntary" because it's a shorter word by three syllables.

The word "quarantine" is preferable to "distancing" or "isolation" because for most people it is more of an abstraction and carries the connotation of a health measure. In contrast, "distancing" and "isolation" both have additional highly unpleasant emotional connotations at a time when people want to *feel* connected even if they are physically separated.

Also, the acronym PSQ is preferable to other combinations: PSD is a file extension for PhotoShop Document (34 million Google hits), PSI is widely used in psychology (39 million Google hits), and both of those are fairly common. PSQ is used in investment management but is less common (only 514,000 Google hits).

In common use, people might say "I'm going into preventive self-quarantine for a week" and then as the term becomes more well known, "I'm taking a week of PSQ" and "employees who can work from home should do PSQ for a week."

OK folks, there's the proposed term and the rationale for it. What do you think? Also I'm going to post this in the most-current blog entry to be sure it gets seen by people who aren't re-reading this entry.

Very good, I like phq, but I see it is already taken.

For URLs, every possible 3-letter combination is already taken, and most 4- and 5-letter combinations.

For general use, same case, almost impossible to find one that hasn't been in use elsewhere. However, PSQ has 1/60 of the Google hits compared to PSI or PSD.

Let's not forget that the original use of the acronym LSD was for an abbreviation of the British currency: Pounds, Shillings, Pence (the Pounds symbol looks like an L, and the Pence symbol is a D), which is the equivalent of "dollars and cents" in USA usage. People in the UK would say "what's the LSD?" as we in the US would say "how does that work out in dollars & cents?" Even after Dr. Hofmann's compound came into wide use in psychiatry and popular culture, the two acronyms lived side-by-side in the UK at least through the 1970s.

In any case an acronym should not require torturing the words that go into it (a common practice in Congress with new bills, e.g. the PATRIOT Act), and it should be easily pronounced. Acronyms acquire semantic meaning with usage over time, for example NASA, IBM, and so on.

@GeorgeT: So there's nothing about influenza in particular? The phrasing seemed to imply that the statement was specific to influenza, which is why I was confused. If it's the willful undermining of quarantines that is the issue, one assumes that this impacts the quarantine vs. isolation decision for *all* infectious diseases (not just influenza), and this would suggest that isolate is almost always better. Is this the case?

I think I'm starting to get off topic now, it's just something that interests me.

I like "flermit", combining flu and hermit. Only two syllables.

Avian Influenza hypothetical models produced 75 as the magic number of people beyond which a Rapid Response" containment wouldn't work. That was assuming rural Thailand chicken farm workers in a small village were the initial infectees. I think it was speculated the magic number might be smaller for an urban chicken farm (maybe harder to track and proximity to airports). So I think you shouldn't add each person that carried the swine flu to their home cities; summing 75 tourists doesn't seem right. I think each case in isolation should form the base of trying not to reach that magic number. For example, the NY school cases were not themselves enough to hit the magic number assuming quarantine of families. In any event the magic number is dependant on R0 and on some differention from regular flu (high death rates or different symptoms or maybe un-flu-season). I don't think the "Rapid Response" contingency should be just abaondoned as everyone seems to think. Rather, I think it should be improvement and specific guidelines be given to only implement it where it will work (ie need CDC to not ignore Veratect warnings).

By Phillip Huggan (not verified) on 29 Apr 2009 #permalink

Given the very high % of people in Mexico who are too poor to get medical help, it's impossible for us to determine if the ones hospitalized in Mexico represent a SMALL PERCENTAGE of the total infected in that country or a LARGE PERCENTAGE of the total people infected. Therefore, we can't know if people in the US are getting a milder version.

It may be that huge numbers of people in Mexico have been infected and aren't being counted because they are too poor to seek medical care or have none near their homes.

By Texas Reader (not verified) on 29 Apr 2009 #permalink

"Therefore, we can't know if people in the US are getting a milder version."

Sorry if I misrepresent your comment, but are you suggesting there are two different strains? No, Mexican and USA samples have been sequenced as near identical (Revere made me aware of this on Saturday and the info was released on Friday or Saturday). They are dying in Mexico City because of the higher risk of pneumonia. For example, efforts could be made to protect Denver over San Fransisco and Tibet over the Maldives were any health authority to dispel the myths these are cytokine storm deaths or acute bronchitis deaths.
But by all means, well-paid masters, let more people die and keep the economy in the crapper.

An interesting line of reasoning is whether slowing down the spread via aggressive social distancing measures is cost-effective. On the pro side it gives you more time to devleop a vaccine (takes months) and more time to mass hospital capacity and quick nurse retraining (weeks?). On the con side it might prolong the virus and give it more time to mutate into a second wave. In any event, this is all a sick joke that people don't realize Mexico City civilians are dying from pneumonia and not something else esoteric. People haven't sarting dying in other cities at risk of pneumonia yet and if they don't it will be a fucking miracle. Are Republicans in charge of this response?! I thought CDC was competant and I thought WHO modelled it's response based on competant Hleath Canada suggestions. I can't imagine Health Canada telling them to change the Phase definitions on the fly...

By Phillip Huggan (not verified) on 29 Apr 2009 #permalink

Phillip, correct me if I am wrong, but my understanding is that the chance of a mutation for a virus goes with the number of cases, not time. A mutation can only happen during the course of an infection. The more infections there are, the more chances there are for a mutation.

There won't be mutations in most cases, so when a mutation does occur it will have to expand from that single case to many cases. If the original strain provides resistance to the mutated strain, then prior infection with the original strain prevents that.

By daedalus2u (not verified) on 30 Apr 2009 #permalink

We're generally in the dark about flu mutations (maybe we'll track down the reservoir of this Swine Flu). The reasoning I was using was that the initial wave of Spanish Flu didn't provide any immunity to subsequent waves (no evidence either way). If it does you are certainly right.

The reasoning I'm using is that in both cases (assuming no early containment) the human reservoir population is identical, but I was thinking animal reservoirs aid in mutation and that the number of these potential reservoirs isn't constant. That is, a flu that sweeps through human won't necessary hit all reservoirs. So I was thinking a population of 10 people near a pig farm provides nearly the same "mutation opportunity" as a population of 100 people near a pig farm; certainly I am thinking the ten people plus pig farm provide much higher mutation opportunities than 1/10 vis-a-vis the 100 people.
That is, two years of a few people sick and inteacting with pigs and birds is nearly twice as bad as all people sick over one year and interacting with animal reservoirs. Minus the animal reservoirs as mutation factors I think you are correct.

By Phillip Huggan (not verified) on 01 May 2009 #permalink

Aidan: That's a question for revere as he made the original statement. "It is a draconian measure and doesn't work for flu and usually makes matters worse. People will intentionally attempt to evade quarantines and in the process spread the disease farther and faster."

From this, I would think it would apply to any illness. I do not see any reason it wouldn't.

The word quarantine originally corresponded to a period of
forty days, which is the length of time that arriving ships suspected of plague infection were
constrained from intercourse with the shore in Mediterranean ports in the 15â19th centuries.
The word quarantine has evolved to mean forced isolation or stoppage of interactions with others.
Over the centuries quarantine has been used to reduce the transmission of human diseases such
as leprosy, plague, cholera, typhus, yellow fever, smallpox, diphtheria, tuberculosis, measles,