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Questions and Answers on the Executive Order Adding Potentially Pandemic Influenza Viruses to the List of Quarantinable Diseases

What is CDC's quarantine authority?

Title 42 United States Code Section 264 (Section 361 of the Public Health Service [PHS] Act) gives the Secretary of Health and Human Services (HHS) responsibility for preventing the introduction, transmission, and spread of communicable diseases from foreign countries into the United States and within the United States and its territories/possessions. This statute is implemented through regulations found at 42 CFR Parts 70 and 71. Under its delegated authority, the Centers for Disease Control and Prevention (CDC) is empowered to detain, medically examine, or conditionally release individuals reasonably believed to be carrying a communicable disease.

Why is an Executive Order necessary?

Under the procedures required under the PHS Act, the list of diseases for which quarantine is authorized must first be specified in an Executive Order of the President, on recommendation of the HHS Secretary. By amending the list to include types of influenza that either cause or have the potential to cause a pandemic, HHS is simply taking the pragmatic step of readying all options as it monitors the emergence of these viruses and makes plans to prevent their spread.

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What does the Executive Order accomplish?

In the event a passenger infected with a novel influenza strain were to arrive in the United States on board an international conveyance (e.g., boat, airplane), the Executive Order provides HHS with clear legal authority to isolate an ill passenger to prevent the passenger from infecting others. This authority would be used only if someone posed a threat to public health and refused to cooperate with a voluntary request.

Were any other diseases added to the list?

No, this Executive Order added only influenza viruses that cause or have the potential to cause a pandemic to the list of communicable diseases for which quarantine is authorized. SARS was added to the list of quarantinable diseases by Executive Order in 2003. The other diseases (Cholera; Diphtheria; infectious Tuberculosis; Plague; Smallpox; Yellow fever; and Viral Hemorrhagic Fevers) have been on the list since 1983.

Have other countries taken similar steps?

Some countries have quarantine authority that covers any public health emergency and therefore includes the types of influenza covered by this Executive Order.

When does CDC use its quarantine power?

CDC issues a few federal isolation orders a year, most commonly in response to travelers with infectious tuberculosis arriving into the United States. During the SARS epidemic in 2003, quarantine and isolation tools were used by state health departments, which have their own, independent authorities.

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What is the difference between isolation and quarantine?

Isolation refers to the separation of persons who have a specific infectious illness from those who are healthy and the restriction of their movement to stop the spread of that illness. Quarantine refers to the separation and restriction of movement of persons who, while not yet ill, have been exposed to an infectious agent and therefore may become infectious. Both isolation and quarantine are public health strategies that have proven effective in stopping the spread of infectious diseases.

When does CDC intend to use these quarantine powers?

In general, CDC defers to the state and local health authorities in their primary use of their own separate quarantine powers. Based upon long experience and collaborative working relationships with our state and local partners, CDC continues to anticipate the need to use this federal authority to quarantine an exposed person only in rare situations, such as events at ports of entry or in similar time-sensitive settings.

What is the difference between pandemic influenza and annual seasonal influenza?

An influenza pandemic is a global outbreak of disease that occurs when a new influenza A virus appears or "emerges" in the human population, causes serious illness, and then spreads easily from person to person worldwide. Pandemics are different from seasonal outbreaks or "epidemics" of influenza. Seasonal outbreaks are caused by subtypes of influenza viruses that are already in existence among people, whereas pandemic outbreaks are caused by new subtypes or by subtypes that have never circulated (spread) among people or that have not circulated among people for a long time. Past influenza pandemics have led to high levels of illness, death, social disruption, and economic loss.

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How would quarantine for pandemic influenza be implemented?

In general, CDC defers to the state and local health authorities in the primary use of their own separate quarantine powers. Implementation of quarantine may depend on individual state and local health authorities as well as the characteristics (e.g., how widespread, who is affected) of the outbreak. However, in providing guidance to state and local health departments and other partners, CDC would most likely recommend voluntary home quarantine when possible, with exposed persons checking themselves for fever and reporting early symptoms to public health authorities. Antiviral drugs may be recommended in some situations.

How long would a person exposed to pandemic influenza be quarantined?

Quarantine of a person exposed to pandemic influenza would last for one incubation period. For annual influenza, the incubation period usually is as long as 4 days; however, this period could be different for a new type of influenza virus.

Why is this Executive Order important now?

The avian (bird) influenza virus in Asia (H5N1) does not usually infect humans. In 1997, however, the first case of spread from a bird to a human was seen during an outbreak of bird flu in poultry in Hong Kong. The virus caused severe respiratory illness in 18 people, 6 of whom died. Since that time, there have been other cases of H5N1 infection among humans. Most recently, human cases of H5N1 infection have occurred in Thailand and Vietnam during large H5N1 outbreaks in poultry. The death rate for these reported cases has been about 70 percent. Most of these cases occurred from contact with infected poultry or contaminated surfaces; however, it is thought that a few cases of human-to-human spread of H5N1 have occurred.

So far, spread of the avian (bird) influenza virus (H5N1) from person to person has been rare, and spread has not continued beyond one person. However, because all influenza viruses have the ability to change, scientists are concerned that the H5N1 virus could one day be able to infect humans and spread easily from one person to another. Because these viruses do not commonly infect humans, there is little or no immune protection against them in the human population. If the H5N1 virus were able to infect people and spread easily from person to person, an "influenza pandemic" (worldwide outbreak of disease) could begin. No one can predict when a pandemic might occur. However, experts from around the world are watching the H5N1 situation in Asia very closely and are preparing for the possibility that the virus may begin to spread more easily and widely from person to person.

Given these conditions, HHS has recommended that influenza caused bynew or re-emerging influenza viruses that are either 1) causing a pandemic or 2) are not in global circulation among humans and have the potential to cause pandemics should be added to the list of communicable diseases for which apprehension, isolation, detention, or conditional release are authorized. This recommendation is based not on intent to impose any quarantine restrictions right now, but rather so that the United States is prepared to respond efficiently and effectively in case of an emergency outbreak situation caused by these influenza viruses, which pose a real threat of global pandemic.

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