Swine Flu Issue Brief | Wednesday, April 29, 2009
By Staff of the Center for Biosecurity
WHO and CDC: Swine Flu Cannot Be Contained
Both the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) have concluded that it is no longer possible to contain the outbreak of swine influenza. This means that given the current geographic spread of disease, it is not feasible to use border closures and/or restrictions or public health measures to limit the spread of the outbreak to new areas. In other words, there are no practical measures that will stop the swine flu outbreak from spreading to any particular location, and there are no measures that can prevent the disease from being spread from country to country.
Travel Restrictions and Border Closures Are Not Effective
Although the WHO has been very clear in asserting that it does not recommend travel restrictions to or from any country or between any locations, several countries have already issued travel restrictions and/or advisories.1 While this may seem a sensible measure, there is no evidence to indicate that such restrictions are effective in limiting the spread of disease [see Center for Biosecurity Swine Flu Issue Brief Border Restrictions: Not an Effective Means of Preventing the Spread of Swine Flu, April 28, 2009].
It is also important to recognize that, according to the CDC, a link to travel to Mexico has been established in only a small number of the individuals infected with swine flu in the U.S.2 This suggests that the swine flu virus is being transmitted from person to person in the U.S., which means that the spread of the disease is beyond the point of containment. What can be done now is to implement commonsense measures that might slow the spread of the virus and lessen its impact—like hand-washing, covering the mouth while coughing, and, most importantly, having sick people stay at home.
Similarity to 1957 Pandemic
Although it is too early and the data is too sparse to conclude with any certainty how this virus will transmit in the U.S., it is important to keep history in mind. In 1957, when there was a relatively mild flu pandemic, infection spread across the U.S. within weeks even though there was less international travel and far less interconnectedness than there is today. There was no clear direction of spread—cases popped up across the country with no discernible pattern—and health authorities had no way to put a border around the infection to contain it. Once cases appeared across the country, the virus was here, and it continued to spread. The same is true now, the virus is here, and it will continue to spread.
In the current epidemic of swine flu, cases are already appearing across the country, in disparate locations, and among people who have not traveled to Mexico. Within a matter of days, cases have been confirmed in Israel, Spain, and New Zealand—countries that are separated by continents and oceans.
Any efforts to contain swine flu are further compromised by our inability to determine the source. In fact, tracking down the origin of any epidemic can be tricky. Although the 1918 pandemic was originally referred to as the “Spanish Flu,” modern researchers now believe that the virus originated on a farm in Kansas. (Proponents of renaming “Swine Flu” as potentially “North American” or “Mexican” Flu should beware).
Containment Requires Speed and Data
In many instances, the origin of outbreaks is never determined. When origins are identified, it is only after an enormous amount of data is collected and analyzed, which also takes time. Given those requirements, it is easy to see why origins are seldom identified in time to implement containment measures, which always require swift and nimble action.
World Health Organization. Press Briefing (Transcript). April 27, 2009. http://www.who.int/csr/disease/swineflu/swineflu_presstranscript_2009_04_27.pdf. Accessed April 29, 2009.
CDC. Press Briefing (Transcript). April 28, 2009. http://www.cdc.gov/media/transcripts/2009/t090428.htm. Accessed April 29, 2009.