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Emergency Operations Center Update on Influenza A(H1N1) Apr 30

EOC Situation Report #7
Influenza A(H1N1)  In the Americas
(Mexico, the United States, Canada)


  • All countries should immediately activate their pandemic preparedness plans, and start implementing the elements designed for phase 5.
  • Countries should remain on high alert for unusual outbreaks of influenza-like illness and severe pneumonia.
  • The PAHO website ( is being constantly updated with new material, including situation reports, recommendations, and frequently-asked questions about the outbreak.

Status of the Region

  • The United States has confirmed a total of 109 human cases of Influenza A(H1N1): 1 in Arizona, 14 in California, 1 in Indiana, 2 in Kansas, 2 in Massachusetts, 1 in Michigan, 1 in Nevada, 50 in New York City, 1 in Ohio, 10 in South Carolina and 26 in Texas.
  • In Mexico, a total of 97 cases have been confirmed. Mexico has reported 1,918 suspected cases of influenza with severe pneumonia including 84 deaths.  Hospital admission rates for suspected cases are slowing. 933 suspected cases are currently hospitalized.
  • In Canada, 19 human cases of Influenza A(H1N1) have been confirmed (2 in Alberta, 4 in the province of New Scotland, 6 in British Columbia and 7 in Ontario); some of them with recent trip history to Mexico.
  • A daily epidemiological report is daily posted on the PAHO website .

Vaccine Recommendations

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

Overall Recommendations

  • It is recommended that National Influenza Centers (NIC) in LAC countries submit to the WHO Collaborating Center for influenza (CDC of the United States) all positive specimens of influenza A that cannot be sub-typed.
  • Seasonal influenza vaccination is to be recommended for all countries, particularly those that do not have seasonal vaccination programs. 
  • WHO/PAHO advises no restriction of regular travel or closure of borders. People who are ill are recommended to postpone travel.
  • There is no risk of infection from this virus from consumption of pork and pork products.

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.


  • At this time, enhanced surveillance is recommended. On its web page , PAHO has published orientations for the enhancement of surveillance activities.
  • 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 refer to their National Influenza Pandemic Plans and implement the steps outlined in them for a Phase 5 alert.

For more information

Map of At-Risk Area

Please click on the map to enlarge it.

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Regional Office for the Americas of the World Health Organization
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