CDC Antiviral Treatment Recommendations

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					                       CDC Influenza Division Key Points
                                       April 19, 2013

In this document:

      Summary Key Points
      FluView Activity Update
      Influenza-Related Pediatric Deaths
      CDC Antiviral Treatment Recommendations
      Message to Health Care Providers: Ordering Flu Vaccine for 2013-2014
      Human Infections of Avian Influenza A (H7N9) Virus in China

Please note, this is the final issue of CDC (Seasonal) Influenza Key Points for the 2012-2013
influenza season. After today, Seasonal Influenza Key Points will no longer be released on a
fixed schedule, but will be issued as warranted, such as in conjunction with the release of
important publications or guidance, unexpected increases in flu activity, etc. H7N9 influenza
key points will continue to be issued weekly unless the epidemiology of the outbreak
changes. Reporting for the 2013-2014 influenza season will begin October 13, 2013 for
Week 40 and appear in FluView, the weekly surveillance report.

Summary Key Points
      Influenza activity continues to decline in the United States. (See Flu Activity Update.)
      However, influenza may continue to spread at low levels and cause illness for several
       weeks in some parts of the country.
      Ten additional pediatric deaths were reported this week, bringing the total to 126
       pediatric deaths for the 2012-2013 influenza season. (See Influenza-Related
       Pediatric Death section.)
      CDC routinely recommends vaccination as long as influenza viruses are circulating,
       but since it takes two weeks for vaccine to become protective and flu activity is
       winding down, the window for vaccination this season is closing.
      However, ongoing vaccination is still recommended in institutional outbreak settings,
       for children needing to complete the second dose in their two-dose regimen, and for
       people preparing to travel to the Southern Hemisphere, which is beginning to enter
       its flu season.
      Because of the ongoing influenza activity, CDC continues to urge people at high risk
       from flu complications, including people 65 and older, to seek treatment quickly if
       they develop flu symptoms including cough, fever, sore throat, and body aches.
      Antiviral treatment can avert serious outcomes and should begin as quickly as
       possible in high risk persons, including people 65 and older, young children,
       pregnant women, and people with certain underlying conditions like asthma, heart
       disease, diabetes and neurological disorders. (See section on CDC’s Antiviral
       Treatment Recommendations.)
      The 2013-2014 influenza vaccine can be ordered at this time from manufacturers
       and distributors. (See section Message to Health Care Providers: Ordering Flu
       Vaccine for 2013-2014.)

CDC Influenza Division Key Points
April 19, 2013

      The World Health Organization (WHO) has reported several human infections with
       avian influenza A (H7N9) viruses in China. These infections have resulted in severe
       illness and, in some cases, death. (See section Human Infections of Avian Influenza
       A (H7N9) in China below.)

FluView Activity Update
      According to the latest FluView report, seasonal influenza activity remains low and
       continues to decline nationally. While the flu season continues to wind down, it’s
       important to remember that flu viruses remain in circulation in the United States
       throughout the year.
      Below is a summary of the key indicators for the week of April 7-13, 2013.
      For the week of April 7-13, the proportion of people seeing their health care provider
       for influenza-like illness (ILI) decreased once again and remains below the national
       baseline for the fourth consecutive week.
      49 states and New York City experienced low or minimal ILI activity. One state
       (Vermont) reported moderate ILI activity. Data from the District of Columbia were
       insufficient to determine an ILI activity level. ILI activity data indicate the amount of
       flu-like illness that is occurring in each jurisdiction.
      41 states, Puerto Rico, and the District of Columbia reported local or sporadic
       geographic influenza activity. Only 9 states reported widespread or regional
       geographic influenza activity. Geographic spread data show how many areas within a
       state or territory are seeing flu activity.
      Since October 1, 2012, 12,170 laboratory-confirmed influenza-associated
       hospitalizations have been reported; an increase of 118 hospitalizations from the
       previous week. This translates to a cumulative rate of 43.7 influenza-associated
       hospitalizations per 100,000 people in the United States for the 2012-2013 season.
          o   Hospitalization data are collected from 15 states and represent approximately
              9% of the total U.S. population. The number of hospitalizations reported does
              not reflect the actual total number of influenza-associated hospitalizations in
              the United States.
      The proportion of deaths attributed to pneumonia and influenza (P&I) based on the
       122 Cities Mortality Reporting System increased slightly this week, but remains
       below the epidemic threshold.
      Ten influenza-related pediatric deaths were reported during the week of April 7-13,
       2013. One of the deaths was associated with an influenza A (H3) virus, one was
       associated with an influenza A 2009 (H1N1) virus, and one was associated with an
       influenza A virus for which the subtype was not determined. Seven of the deaths
       were associated with influenza B viruses. This brings the total number of influenza-
       associated pediatric deaths reported to CDC for 2012-2013 to 126. Additional
       information regarding pediatric deaths is available through FluView Interactive.
      Nationally, the percentage of respiratory specimens testing positive for influenza in
       the United States during the week of April 7-13 decreased for the fifteenth

CDC Influenza Division Key Points
April 19, 2013

       consecutive week. Influenza B viruses accounted for 74% of all reported influenza
       positive specimens this week.
      Influenza A (H3N2), 2009 influenza A (H1N1), and influenza B viruses have all been
       identified in the U.S. this season. During the week of April 7-13, 93 of the 354
       influenza-positive tests reported to CDC were influenza A viruses and 261 were
       influenza B viruses. Of the 34 influenza A viruses that were subtyped, 52.9% were
       H3 viruses and 47.1% were 2009 H1N1 viruses.
      Since October 1, 2012, CDC has antigenically characterized 2,144 influenza viruses,
       including 209 2009 influenza A (H1N1) viruses, 1,200 influenza A (H3N2) viruses and
       735 influenza B viruses.
          o   Of the 209 2009 influenza A (H1N1) characterized, 206 (98.6%) were
              characterized as A/California/7/2009-like. This is the influenza A (H1N1)
              component of the Northern Hemisphere vaccine for the 2012-2013 season.
          o   Of the 1,200 influenza A (H3N2) viruses, 1,196 (99.7%) were characterized
              as A/Victoria/361/2011-like. This is the influenza A (H3N2) component of the
              Northern Hemisphere influenza vaccine for the 2012-2013 season.
          o   Of the 735 influenza B viruses characterized, 67.2% belonged to the
              B/Yamagata lineage of viruses, and were characterized as
              B/Wisconsin/1/2010-like, the influenza B component for the 2012-2013
              Northern Hemisphere influenza vaccine. The remaining 32.8% of the tested
              influenza B viruses belonged to the B/Victoria lineage of viruses.
      Since October 1, 2012, 483 2009 influenza A (H1N1), 1,821 influenza A (H3N2), and
       783 influenza B virus samples have been tested for resistance to neuraminidase
       inhibitors. While the vast majority of the tested virus samples (>99%) showed
       susceptibility to the antiviral drugs oseltamivir and zanamivir, two 2009 H1N1
       viruses (reported during week 3 and week 6) and two influenza A (H3N2) viruses
       (reported during weeks 10 and 11) showed resistance to oseltamivir. High levels of
       resistance to the adamantanes (amantadine and rimantadine) persist among 2009
       influenza A (H1N1) and A (H3N2) viruses. Adamantanes are not effective against
       influenza B viruses.
      FluView is available – and past issues are archived – on the CDC website.
   Note: Delays in reporting may mean that data changes over time. The most up to date
   data for all weeks during the 2012-2013 season can be found on the current FluView
   webpage at

Influenza-Related Pediatric Deaths
      Ten pediatric deaths were reported during the week of April 7 – 13, 2013.
      A total of 126 influenza-associated pediatric deaths have been reported during the
       2012-2013 season from Chicago [1], New York City [4] and 37 states (AL [1], AR
       [4], AZ [3], CA [4], CO [5], FL [8], GA [2], HI [1], IA [1], IL [1], IN [4], KS [2], KY

CDC Influenza Division Key Points
April 19, 2013

       [1], LA [1], MA [4], MD [3], ME [1], MI [6], MN [4], MS [1], NE [1], NH [3], NJ [7],
       NM [3], NV [1], NY [8], OH [4], OK [1], PA [1], SC [4], SD [3], TN [3], TX [16], UT
       [3], VA [1], WA [1], and WI [4]).
      A pediatric death is a death in a person younger than 18 who died from an illness
       related to infection with an influenza virus.
      A preliminary review of the available 2012-2013 pediatric death reports indicates
          o   54% of deaths occurred in children who were at high risk of developing
              serious flu-related complications. However, 46% had no recognized chronic
              health problems.
          o   About 90% of flu-related deaths were in unvaccinated children.
          o   The proportions of pediatric deaths that occurred in unvaccinated children and
              among children at high risk from flu complications are largely consistent with
              what has been seen in the past.
      Since 2004, when pediatric deaths associated with influenza infection became a
       nationally notifiable condition, the number of deaths reported to CDC each year has
       ranged from 34 (2011-2012 season) to 122 deaths (2010-2011 season).
      During the 2009 H1N1 pandemic — April 15, 2009 to October 2, 2010 — 348
       pediatric deaths were reported to CDC.
      These deaths are a somber reminder of the danger flu poses to children.
      The single best way to protect against seasonal flu and its potential severe
       consequences is to have children receive a seasonal flu vaccine each year.
      Vaccination is especially important for children younger than 5 years of age and
       children of any age with an underlying medical condition like asthma, a neurological
       or neurodevelopmental disease, or immune suppression. These children are at higher
       risk of serious complications if they get the flu.
      Information about the pediatric deaths, including basic demographics, underlying
       conditions and time and place of death, is collected through the Influenza-Associated
       Pediatric Mortality Surveillance System. Information for the 2012-2013 season is
       now available through the Influenza Associated Pediatric Mortality application of
       FluView Interactive at
      Yearly vaccination also is especially important for people in contact with high risk
       children in order to protect the child (or children) from the flu.
      Even previously healthy children can become seriously ill if they get the flu. The
       latest laboratory-confirmed influenza hospitalization data reported in this week’s
       FluView indicate that approximately 46% of children hospitalized with the flu had no
       identified underlying medical conditions.
      Flu-related deaths in children younger than 18 years old should be reported through
       the Influenza-Associated Pediatric Mortality Surveillance System. The number of flu-

CDC Influenza Division Key Points
April 19, 2013

       associated deaths among children reported during the 2012-2013 flu season will be
       updated each week and can be found at

CDC Antiviral Treatment Recommendations
      Clinical benefit is greatest when antiviral treatment is administered early. When
       indicated, antiviral treatment should be started as soon as possible after illness
       onset, ideally within 48 hours of symptom onset. However, antiviral treatment might
       still be beneficial in patients with severe, complicated or progressive illness and in
       hospitalized patients when started after 48 hours of illness onset, as indicated by
       observational studies.
      Antiviral treatment is recommended as early as possible for any patient with
       confirmed or suspected influenza who
          o   is hospitalized;
          o   has severe, complicated, or progressive illness; or
          o   is at higher risk for influenza complications.
      Treatment of persons with suspected influenza should not wait for laboratory
       confirmation of influenza. While influenza vaccination is the first and best way to
       prevent influenza, a history of influenza vaccination does not rule out the possibility
       of influenza virus infection in an ill patient with clinical signs and symptoms
       compatible with influenza.
      Antiviral treatment also can be considered for any previously healthy, symptomatic
       outpatient not at high risk with confirmed or suspected influenza on the basis of
       clinical judgment, if treatment can be initiated within 48 hours of illness onset.
      More information is available at

Message to Health Care Providers: Ordering Flu Vaccine for 2013-2014
      On April 19, 2013, CDC posted “Interim Recommendations: Prevention and Control
       of Influenza with Vaccines: Recommendations of the Advisory Committee on
       Immunization Practices: (ACIP), 2013” which includes information on flu vaccines in
       the United States for the 2013-2014 season. These recommendations are available
          o   The document summarizes recommendations for the use of influenza vaccines
              approved on February 21, 2013 by ACIP.
          o   An expanded 2013 ACIP influenza vaccination recommendation statement will
              be published in MMWR Recommendations and Reports prior to the start of the
              2013-2014 influenza season.

CDC Influenza Division Key Points
April 19, 2013

          o   Providers should consult the expanded 2013 ACIP influenza vaccination
              statement when available for complete and updated information.
      The 2013-2014 influenza vaccine can be ordered at this time from manufacturers
       and distributors.
      As the 2012-2013 flu season has shown, it is important to pre-book vaccine as soon
       as it is available.
      Most of the flu vaccine offered for the 2013-2014 season will be trivalent (three-
      Some quadrivalent (four-component) vaccine will be available as well according to
       manufacturers; however, supplies are expected to be limited.
      All nasal spray vaccine is expected to be quadrivalent, however, this makes up only a
       small portion of total vaccine availability.
          o   Ordering flu vaccine should not be delayed if quadrivalent flu vaccine is not
      Trivalent vaccine offers important protection from flu.

Human Infections of Avian Influenza A (H7N9) in China
      Cases of human infection with a new avian influenza A (H7N9) virus continue to be
       detected in China.
      No cases of H7N9 have been detected in the United States or anywhere outside of
       China at this time.
      The first human infections with H7N9 were reported by the Chinese National Health
       and Family Planning Commission to the World Health Organization (WHO), which
       formally reported these cases on April 1, 2013.
      As of April 19, 2013, 12:00PM EDT, there have been 91 reported cases of human
       infection with this new H7N9 virus; 17 people have died.
      Most of the reported cases of human infection with this virus have had very serious
       illness. There also are reports of some milder illness and one person who tested
       positive for the virus did not have any symptoms. (This asymptomatic person who
       tested positive for the virus is not included in the case count because they do not
       meet the Chinese case definition for H7N9.)
      There is currently no vaccine available to protect against avian influenza A (H7N9)
       virus. However, CDC is developing an H7N9 vaccine candidate virus that could be
       used to make a vaccine in the event that it is needed.
      Since this H7N9 virus is novel influenza virus with pandemic potential, the situation
       in China is being carefully investigated.
      After the first human infections with H7N9 were detected, Chinese authorities
       detected H7N9 viruses in poultry in the same area where human infections have
      The extent of the avian outbreak in poultry is still being assessed; but China has
       reportedly begun culling birds in live markets.

CDC Influenza Division Key Points
April 19, 2013

      Many of the human cases of H7N9 are reported to have had contact with poultry;
       however, some cases reportedly have not had such contact.
      Since this virus does not normally spread in people, the working assumption is that
       people have been infected with the virus after having contact with infected poultry.
          o   Infected birds can shed a lot of flu virus, for example, in their droppings or
              their mucus. If someone touches an infected bird or an environment
              contaminated with virus and then touches their eyes, nose or mouth, they
              may be infected with bird flu virus.
          o   There is some evidence that infection may also occur if the flu virus becomes
              airborne somehow, such as when an infected bird flaps it wings. If someone
              were to breathe in airborne virus, it’s possible they could get infected.
      China is conducting follow-up investigations among close contacts of people infected
       with H7N9 to try to assess whether human-to-human spread of this virus is
      These investigations suggest that there is no sustained (ongoing) spread of this virus
       from person to person at this time.
      Human infections with avian influenza viruses are rare and most often occur after
       people are in contact with an infected bird (either live or dead) or environments
       contaminated with avian flu virus.
      However, non-sustained person-to-person spread of other avian influenza viruses is
       thought to have occurred in the past, most notably with H5N1 viruses.
      Based on this previous experience with other avian influenza viruses, it’s likely that
       some limited human-to-human spread of this H7N9 virus will be detected.
      However, it’s important to remember that human-to-human transmission ranges
       along a continuum; from occasional, “dead-end” human-to-human transmission, to
       efficient and sustained human-to-human transmission.
      “Dead end” transmission usually refers to when a virus from an animal host infects a
       person and then there is some subsequent transmission that eventually burns out.
      For example, when a host infects one person who then subsequently infects someone
       else that is called “first generation spread.” If that second person then infects
       someone else that is called “second generation spread,” and so forth.
      Previously, third generation transmission of H5N1 viruses has been documented in
       one instance at least (Pakistan). (WHO, Weekly Epidemiological Record. “Human
       cases of avian influenza A(H5N1) in North-West Frontier Province, Pakistan,
       October–November 2007.”)
      However, efficient and sustained (ongoing) transmission in the community is needed
       for an influenza pandemic to begin.
      There is no evidence that the H7N9 virus in China is spreading in a sustained,
       ongoing way at this time, but this is an evolving situation and there is still much to

      On Thursday, April 18, CDC posted Interim Guidance on the Use of Antiviral Agents
       for Treatment of Human Infections with Avian Influenza A (H7N9).

CDC Influenza Division Key Points
April 19, 2013

      On Friday, April 19, 2013, CDC posted a Questions & Answers document called
       “H7N9 Flu and You” for the public. This Q&A is available at


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