pandemic influenza




When news of the outbreak of a new flu strain emerged, WHO, CDC, and others referred to the virus as H1N1 “swine influenza” or “swine-origin influenza.” This is based on the presumed evolutionary origin of the strain from strains that circulate in swine, since it contains genetic material typically found in North American and Eurasian swine flu strains. There has been no evidence to date that pigs are involved in the transmission of this virus to humans, however. There have been concerns that the term “swine flu” has had unwarranted economic and trade implications for swine and pork products, among other concerns. Others have raised concerns that because of religious practices that call for the avoidance of swine and pork products by some persons of Jewish or Muslim faiths, disease control measures may be compromised in these groups if illness is perceived as a social stigma. On April 29, 2009, officials from HHS, DHS, and other federal agencies referred to the virus as “2009 H1N1.” On April 30, 2009, WHO began referring to the new strain as influenza A(H1N1).

On May 2, the Canadian Food Inspection Agency reported finding the H1N1 outbreak strain in a swine herd in Alberta, the first time the strain has been identified in swine. Preliminary investigation suggests that the herd was exposed to the virus from a Canadian worker who had recently returned from Mexico and had been exhibiting flu-like symptoms when he worked in proximity to the swine.

Key State and Local Actions

School Closures

When the H1N1 outbreak first began in the United States, many affected communities closed schools when students were found to be infected with the new flu strain. Legal authority to close schools rests with state or local officials and is highly variable among the states. A CDCrequested study found that school closure is legally possible in most jurisdictions during both routine and emergency situations. The study also indicated that state authority for closure may be vested at various levels of government and in different departments, generally the state or local education agencies or state or local departments of health.

In keeping with its obligation to provide public health assistance to states, on May 1, CDC, in consultation with the U.S. Department of Education, issued guidance with respect to school closures during the outbreak, recommending that “affected communities with laboratoryconfirmed cases of influenza A H1N1 consider adopting school dismissal and childcare closure measures, including closing for up to 14 days depending on the extent and severity of illness.”

The guidance for this particular outbreak was derived from earlier broad guidance for pandemic planners, issued by CDC in 2007.

School closures are challenging for all parties involved. Among other things, parents must find alternate arrangements for care of their children, educators must adopt alternate means of delivering their services, and children’s education may be compromised. On May 5, CDC officials reissued their guidance regarding school closures. Noting that the disease appeared to be widespread and generally mild, CDC said that under the circumstances, widespread school closures may be more burdensome than beneficial to affected communities. The revised guidance recommended against closures based on individual cases of H1N1 flu. It recommended instead that emphasis be placed on keeping sick students and employees home, and that closings be considered if the burdens of infection and absenteeism were substantial.

Early in the H1N1 outbreak, officials in some school districts were criticized for being too aggressive, sometimes closing schools in entire districts for isolated cases in individual schools. Since then, New York City has continued to struggle with H1N1 outbreaks in schools, prompting “some parents, school staff and teachers’ union officials [to wonder] whether the city was moving too slowly to close schools with high absenteeism.” CDC’s actions and those of local education authorities illustrate the challenges facing government officials as they attempt to make evidencebased decisions about community mitigation interventions in a constantly changing environment.

As with CDC guidance in general, recommendations regarding school closure are intended to be weighed by local officials in light of local circumstances. In the original guidance, as quoted above, CDC recommended that state and local officials “consider adopting school dismissal and childcare closure measures, including closing for up to 14 days depending on the extent and severity of illness.” Although this language placed considerable discretion in local hands, local officials may initially have been reluctant to scale back from immediate 14-day closures when the virus was detected. In addition to initial uncertainty about the outbreak’s severity, there may also have been uncertainty about local decision-making protocols. In an assessment of state pandemic flu preparedness conducted by HHS and DHS in 2007 through 2008, planning for student dismissal and school closure was found to be a weakness among the states. More than half of them were graded as having either “many major gaps” or “inadequate preparedness” for this planning task. The H1N1 outbreak will inform efforts by CDC, the Department of Education, and state and local officials to study “lessons learned” and refine their plans for future incidents.

Additional Information

• Mexico, Ministry of Health (in Spanish):
• Canada: Public Health Agency of Canada: swine_200904-eng.php; Canadian Food Inspection Agency:
• Security and Prosperity Partnership of North America, North American Plan for Avian and Pandemic Influenza, August 2007, nsf/vwapj/pandemic-influenza.pdf/$FILE/pandemic-influenza.pdf
• Center for Infectious Disease Research and Policy (CIDRAP), at the University of Minnesota, frequent updates, including scientific and technical information,
• Centers for Law and the Public’s Health: A Collaborative at Johns Hopkins and Georgetown Universities, H1N1 (Swine Flu) Legal Preparedness and Response page: includes updates of “U.S. Federal, State, or Local Declarations of Emergency or Public Health Emergency,”

Source :
The 2009 Influenza Pandemic: An Overview
Sarah A. Lister Specialist in Public Health and Epidemiology
C. Stephen Redhead Specialist in Health Policy
June 12, 2009

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Case Management & Infection Control
Who should be tested?
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