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Emergency Operations Center Update on Influenza A(H1N1) Apr 29

EOC Situation Report #6 - Influenza A(H1N1) In The Americas (Mexico, The United States, Canada)


  • The Director-General of the World Health Organization, Dr. Margaret Chan, has declared Phase 5 on the WHO pandemic ranking scale this afternoon, April 29.
  • This follows the confirmation of evidence of sustained human-to-human transmission in at least two countries in the same region, Mexico and the U.S.
  • The implications of the declaration may affect international travel.  Countries should begin implementing their national influenza plans.
  • PAHO/WHO has deployed a multidisciplinary team of experts to Mexico, drawn from PAHO/WHO headquarters (Geneva and Washington) and country offices, and national institutions in Chile, Nicaragua, Costa Rica, Panama, Uruguay. The team also includes four experts from the U.S. Centers for Disease Control and Prevention. These experts support Mexico’s Secretary of Health and are engaged in analysis, field investigations, risk communications, logistics and emergency management. They report daily to WHO and PAHO.

Status of the Region

  • The United States has reported its first death due to H1N1; a total of 91 cases are laboratory confirmed.
  • Mexico has reported 26 confirmed cases with 7 deaths. However, these figures can significantly vary over the next two days when laboratory tests of the probable cases under investigation are completed.
  • Canada has reported 13 cases with no deaths.
  • A daily epidemiological report is daily posted on the PAHO website .

Vaccine Recommendations

  • There is still no vaccine for the new strain of Influenza A(H1N1).
  • There is no evidence that the seasonal influenza vaccine, currently being used, would provide any protective effect against the new Influenza A(H1N1) virus.
  • Given that cases of seasonal influenza and pandemic Influenza A(H1N1) can occur at the same time, vaccination with the seasonal vaccine should continue in order to avoid cases of seasonal influenza.

Overall Recommendations

  • WHO/PAHO advises no restriction of regular travel or closure of borders.
  • There is no risk of infection from this virus from consumption of pork and pork products.
  • Individuals are advised to wash their hands thoroughly with soap and water on a regular basis and should seek medical attention if they develop any symptoms of influenza-like illness.
  • It is strongly recommended that people who are sick should postpone travel. People who have recently traveled, and have become ill, should seek medical attention.

WHO Pandemic Influenza Preparedness and Response Guidance 2009, Definition of Phases

Phase WHO Pandemic Influenza Preparedness and Response Guidance, 2009
Phase 1 No animal influenza virus circulating among animals has been reported to cause infection in humans.
Phase 2 An animal influenza virus circulating in domesticated or wild animals is known to have caused infection in humans and is therefore considered a specific potential pandemic threat.
Phase 3 An animal or human-animal influenza reassortant virus has caused sporadic cases or small clusters of disease in people, but has not resulted in human-to-human transmission sufficient to sustain community-level outbreaks.
Phase 4 Human-to-human transmission (H2H) of an animal or human-animal influenza reassortant virus able to sustain community-level outbreaks has been verified.
Phase 5 The same identified virus has caused sustained community level outbreaks in two or more countries in one WHO region.
Phase 6 In addition to the criteria defined in Phase 5, the same virus has caused sustained community level outbreaks in at least one other country in another WHO region.
Post-peak period Levels of pandemic influenza in most countries with adequate surveillance have dropped below peak levels.
Possible new wave Level of pandemic influenza activity in most countries with adequate surveillance rising again.
Post-pandemic period Levels of influenza activity have returned to the levels seen for seasonal influenza in most countries with adequate surveillance.


  • WHO has published guidelines for the surveillance of human infection for National Focal Points for the International Health Regulations (IHR). It includes a case definition for surveillance purposes.
  • WHO information on the use of antiviral treatments for influenza including tamiflu is available online.


  • WHO will be tracking the pandemic at the epidemiological, clinical, and virological levels.
  • The results of these ongoing assessments will be issued as public health advice, and made publicly available.
  • All countries should immediately activate their pandemic preparedness plans. Countries should remain on high alert for unusual outbreaks of influenza-like illness and severe pneumonia.
  • At this stage, effective and essential measures include heightened surveillance, early detection and treatment of cases, and infection control in all health facilities.

For more information

Map of At-Risk Area

Summary of locations with reported deaths (red triangles) and confirmed cases (blue icons).

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