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PAHO Epidemiological Alert: Beginning influenza season in the Caribbean and South America 28 March 2014

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  • PAHO Epidemiological Alert: Beginning influenza season in the Caribbean and South America 28 March 2014

    Epidemiological Alert

    Beginning influenza season in
    the Caribbean and South America
    28 March 2014

    As the Southern Hemisphere influenza season in the Caribbean and South America is
    approaching, the Pan American Health Organization / World Health Organization
    (PAHO/WHO) recommends Member States start preparing for influenza season that might
    be similar to the one seen in the Northern Hemisphere. Actions should include provision of
    seasonal influenza vaccination to reach the most at risk populations, increasing public
    awareness of influenza prevention methods, strengthening influenza surveillance, and
    strengthening of health services.

    Situation summary

    To prepare for the upcoming influenza season in the Caribbean and South America, it is
    important to consider the 2013-2014 influenza season in the Northern Hemisphere. The
    season was characterized by the predominance of influenza A(H1N1)pdm091
    and mainly
    young adults were affected.

    In Canada, the predominant virus was influenza A(H1N1)pdm09. Of more than 18,000
    cases for which information on age and influenza type/sub-type was available, 55%
    occurred in individuals between the ages of 20 and 64 years. Of the influenza-associated
    hospitalizations recorded between the start of the season2
    and epidemiological week (EW)
    11 of 2014, there were 1,250 influenza-associated hospitalizations, 88% of which were due to
    influenza A(H1N1)pdm09. Of those hospitalized, 73% had not been vaccinated against
    influenza. More than three-quarters of the hospitalizations and approximately 80% of
    patients admitted to Intensive Care Units (ICU) were 45 years or older.

    In Mexico, influenza A(H1N1)pdm09 virus was predominant as well. From the beginning
    of the season to EW 12 of 2014, 6,627 influenza cases were recorded. Of these cases, 5,241
    (79%) were confirmed as influenza A(H1N1)pdm09, and a majority occurred among those
    aged 30 to 44 years. Of 704 deaths recorded, 531 (75%) occurred in the 40 to 59 year age
    group, 68% had at least one comorbid condition, and 90% of them had not been
    vaccinated against influenza.

    In the United States of America, influenza A(H1N1)pdm09 virus was also predominant
    and approximately 61% of influenza hospitalizations occurred among those aged 18 to 64
    years. This number is higher than that recorded in the previous influenza season when
    influenza A(H3N2) predominated. During the 2013-2014 influenza season, 25 to 64 year-olds
    accounted for almost 60% of influenza deaths, exceeding numbers from the last three

    1 Influenza A(H1N1)pdm09 is a seasonal virus, signifying that it will continue to circulate like other influenza viruses.
    2 Epidemiological week 40 of 2013.

    influenza seasons when they accounted for 18% (2012-2013), 30% (2011-2012) and 47%
    (2010-2011) of deaths. During the 2009-2010 pandemic, 63% of deaths occurred in those
    between 25 and 64 years of age.

    In summary, the 2013-2014 influenza season in the Northern hemisphere was
    characterized by a predominant circulation of influenza A(H1N1)pdm09 and, according to
    available data, primarily affected young adults. These trends might not be replicated in the
    same manner in the Southern hemisphere; however, they offer possible lines of action for
    countries to prepare themselves.


    The Pan American Health Organization / World Health Organization (PAHO/WHO)
    recommends that those Member States of the Caribbean and South America where the
    influenza season is beginning, start to prepare for an influenza season potentially similar to
    that observed in the Northern hemisphere. In order to prevent hospitalizations and avoid
    deaths, seasonal influenza vaccination efforts should be accelerated to reach the most-at-risk populations. In addition, public awareness campaigns on influenza prevention methods
    should be implemented. PAHO/WHO also recommends strengthening health services to
    address the possible increase in patients, and ensure appropriate clinical management and
    an adequate supply of antivirals and surveillance activities.


    PAHO/WHO recommends that, due to the increased vulnerability to developing
    complications, pregnant women be given the highest priority in influenza vaccination
    programs. Additional at-risk groups include, in no particular order, children aged 6?59
    months (especially those between 6 months to 2 years old), the elderly, individuals with
    specific chronic medical conditions, and health-care workers.

    Countries already implementing influenza vaccination programs targeting any of these
    groups should continue to do so, also making sure to incorporate immunization of pregnant

    Information for the Public

    PAHO/WHO recommends that Member States strengthen their public communication
    and outreach efforts from the earliest point of the onset of the influenza season. The public
    should be informed of what seasonal influenza is, what its risks are, how it can be prevented,
    and how it is treated. The public should be reminded of the fact that the primary form of
    influenza transmission is through interpersonal contact. Given this, it is also important to:

    - Remind the public that washing hands is the most effective way of reducing
    - Disseminate ?respiratory etiquette? knowledge to help prevent transmission of the
    - Recommend that persons with fever not leave their home to go to work or to other
    public places until the fever has subsided.
    continues at
    Twitter: @RonanKelly13
    The views expressed are mine alone and do not represent the views of my employer or any other person or organization.