Understanding Interventions

All actions taken to prevent the spread of an infectious disease or to treat it are called interventions. In an outbreak, public health officials can choose from two different kinds of interventions: Pharmaceutical and non-pharmaceutical interventions (also called medical or non-medical interventions.) This page explains these options, including clarifying the difference between quarantine and isolation, and offers some story ideas.

On this page...
  Major interventions in a pandemic »
  How do interventions work? »
  Why isolation and quarantine are not the same »
  Story ideas »

Major interventions in a pandemic

The major pharmaceutical interventions in a pandemic are:


The major non-pharmaceutical interventions are 1

Isolation and supportive treatment of all people suspected to have influenza, with the isolation occurring in the home or healthcare setting.
Voluntary home quarantine of members of households with confirmed or probable influenza case(s).
Social distancing of children, for example school closure and/or suspension of all school-based activities and childcare programs.
Social distancing of adults in the community and workplace, including canceling large public gatherings and altering work environments and schedules to decrease density.
Screening of travelers

How do interventions work?

Antiviral drugs may treat the illness if given 48 hours after the onset of symptoms–but only if the new pandemic strain responds to the drug.

Vaccines prevent infection with the new strain—but only if they arrive in time and before the pandemic has already spread through the population.

All non-pharmaceutical interventions have the same goals. Ideally, they would:

Delay a rapid increase in cases and buy time for implementation of pharmaceutical interventions.
Decrease the number of cases occurring at any one time to avoid overtaxing health resources.
Reduce the total number of influenza cases and thus overall morbidity and mortality.

However, how well non-pharmaceutical interventions work is a tricky question and depends on the circumstances, public opinion about these interventions, and simple practicalities. For example, immediate school closings, an intervention thought to be an important choice for local health officials before the 2009 H1N1 pandemic struck, turned out to be less effective and more problematic than anticipated. (See story ideas below.)

Why isolation and quarantine are not the same

Isolation and quarantine are technical terms that are not interchangeable.

The Centers for Disease Control defines isolation as

“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.”2

Story Ideas

1. What non-pharmaceutical interventions are considered in your local plans and what can you find out about how well they might actually work? The Trust for America’s health has a good write up of “10 early lessons learned from the response to the H1N1 (swine) flu outbreak.”
  Historic examples and helpful thoughts can also be found in a policy review by the World Health Organization Writing Group.
2. Quarantine and isolation laws vary from state to state. What are the rules in your state, when was the last time they were invoked and have they been updated?
  There is a model State Emergency Health Powers Act, developed after the anthrax attacks of 2001, which some regard as open to abuse. Has your state passed such a law yet? For more detailed information on the legal issues surrounding quarantine and isolation, see the 2007 report on “Federal and State Quarantine and Isolation Authority” from the Congressional Research Service for more details.
  Also helpful in researching this question are the public health law Web site of the Centers for Disease Control and Prevention and the newsfeed from the Centers for Public Health Law, sponsored by Johns Hopkins and Georgetown Universities.


  1. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, U.S. Agency for International Development, Non-Pharmaceutical Interventions for Use During a Human Influenza Pandemic, December 2007.

  2. Centers for Disease Control and Prevention, Fact Sheet on Isolation and Quarantine, May 2005.

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