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Swine Flu Update: Border Closures • Rapid Flu Tests • EUAs and Diagnostic Tests • Epi Update • Guidance from CDC • Guidance from WHO

By the Staff of the Center for Biosecurity | April 28, 2009 | 8:00 PM, EST

Note: Following advice from an expert panel, the WHO recommended yesterday that nations SHOULD NOT close borders or restrict international travel to control swine flu. The Center for Biosecurity has prepared an issue brief, Border Restrictions: Not an Effective Means of Preventing the Spread of Swine Flu

Rapid Influenza Tests Have Limited Utility for Swine Flu

The diagnosis of swine flu cannot be definitively established with rapid testing. Rapid influenza antigen tests have moderate sensitivity and cannot be used to rule out influenza infection. Additionally, if a rapid test is positive, that result only indicates the presence of influenza A and/or B, not the type of influenza virus present. An individual infected with swine flu may or may not be positive for influenza A on a rapid test, but the result would be indistinguishable from that of an individual infected with seasonal influenza A.1

FDA Issues Authorizations for Emergency Use of Antivirals, Diagnostic Tests

On April 27, 2009, the U.S. Food and Drug Administration (FDA) issued Emergency Use Authorizations (EUAs) in response to requests by the Centers for Disease Control and Prevention (CDC) for the swine flu outbreak.2 One of the reasons the EUAs could be issued was because the U.S. Department of Health and Human Services (HHS) declared a public health emergency on April 26, 2009.3

The swine influenza EUAs do several things to aid in the current response:

  1. Tamiflu: Allow for Tamiflu to be used to treat and prevent influenza in children under 1 year of age, and to provide alternate dosing recommendations for children older than 1 year. Tamiflu is currently approved by the FDA for the treatment and prevention of influenza in patients 1 year and older.

  2. Tamiflu and Relenza: Allow for both antivirals to be distributed to large segments of the population without complying with federal label requirements that would otherwise apply to dispensed drugs and to be accompanied by written information about the emergency use of the medicines.

  3. Diagnostic Test: Allow CDC to distribute the rRT-PCR Swine Flu Panel diagnostic test to public health and other qualified laboratories that have the equipment and personnel to perform and interpret the results.2

Epidemiology Update

As of today, a total of 64 cases of swine flu have been confirmed in 5 states: 45 in NY; 1 in OH; 2 in KS; 10 in CA; 6 in TX.4  In a CDC conference call, Acting Director Richard Besser gave additional details on cases that have been confirmed to date5:

  • 5 cases hospitalized: 3 in CA; 2 in TX. CDC expects to find additional hospitalizations, which is typical for seasonal influenza.

  • Median age of cases is 16 years, with range of 7 to 54 years.

  • Incubation period is currently estimated at 2 to 7 days.

New Zealand, Scotland, Spain, Canada, and Israel have also confirmed cases.  Several other countries have suspected, but not laboratory-confirmed cases.6

Updated Guidance/Advisory Documents from CDC

On April 27, 2009, the CDC issued a travel advisory that recommends against all non-essential travel to Mexico.7

The CDC also released revised antiviral guidelines: Interim Guidance on Antiviral Recommendations for Patients with Confirmed or Suspected Swine Influenza A (H1N1) Virus Infection and Close Contacts (April 28, 2009):

Changes made to the previous version include the following (a link to the earlier version was included in a CBN Swine Flu Update on April 24, 2009):

  • Addition: criteria for “probable cases” added;

  • Deletion: recommendations for use of adamantine drugs to cover the possibility of seasonal flu; and

  • Addition: information relating to the use of oseltamivir in children under one year of age.8

In addition, CDC posted the following guidance documents:

New Guidance from the WHO


  1. Uyeki T. Swine Influenza Investigation Update. April 27, 2009. Accessed April 28, 2009.

  2. FDA authorizes emergency use of influenza medicines, diagnostic test in response to swine flu outbreak in humans [news release]. Rockville, MD: U.S. Food and Drug Administration. April 27, 2009. Accessed April 28, 2009.

  3. HHS declares public health emergency for swine flu [news release]. Washington, DC: U.S. Department of Health and Human Services. April 26, 2009. Accessed April 27, 2009.

  4. CDC. Swine Influenza (Flu). April 28, 2009. Accessed April 28, 2009.

  5. CDC. Swine Flu Press Briefing. April 28, 2009. 

  6. Mc Neill DG.  7 Countries Have Confirmed Flu Cases. New York Times. April 28, 2009. Accessed April 28, 2009

  7. CDC. Travel Warning: Swine Influenza and Severe Cases of Respiratory Illness in Mexico — Avoid Nonessential Travel to Mexico. April 27, 2009. Accessed April 27, 2009.

  8. CDC. Interim Guidance on Antiviral Recommendations for Patients with Confirmed or Suspected Swine Influenza A (H1N1) Virus Infection and Close Contacts. April 28, 2009. Accessed April 28, 2009.