Transcript No Slide Title

Novel Influenza A (H1N1)
United States, 2009
ACHA 2009 Annual Meeting
May 27th, 2009, San Francisco
Jane Seward, M.B.B.S., M.P.H
Acting Deputy Director
National Center for Immunization and Respiratory Diseases
Centers for Disease Control and Prevention
The findings and conclusions in this presentation are those of the authors and do not necessarily
represent the views of the Centers for Disease Control and Prevention
Outline
 Influenza and influenza virus
 Antigenic changes and pandemic
viruses
 Novel influenza A H1N1
 U.S.
 Global
 Guidance documents
 Institutions of Higher Learning
 Vaccine and next steps
 Summary
Influenza

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

Highly infectious viral illness
First pandemic in 1580
At least 4 pandemics in 19th century
Estimated 21 million deaths worldwide in pandemic
of 1918-1919
 Virus first isolated in 1933
Seasonal Influenza, U.S.
Annual Average Disease Burden
 15 – 60 million cases
(5 – 20% of U.S. population)
 200,000 hospitalizations
 36,000 deaths
Prevention of Influenza, Recommendations of ACIP
MMWR 2008; 57 (RR-7)
Influenza Virus
 Single-stranded RNA virus
 Orthomyxoviridae family
 3 types:
 A: moderate/severe disease, humans – all ages,
animals
 B: milder disease, children, humans
 C: rarely reported humans
 Subtypes of type A determined by hemagglutinin
and neuraminidase
Influenza Virus
Type of nuclear
material
Neuraminidase
Hemagglutinin
A/Fujian/411/2002 (H3N2)
Virus
type
Geographic
origin
Strain
number
Year of
isolation
Virus
subtype
Influenza Antigenic Changes
 Hemagglutinin and neuraminidase antigens change with
time
 Changes occur as a result of point mutations in the virus
gene (antigenic drift), or due to exchange of a gene segment
with another subtype of influenza virus (antigenic shift)
 Impact of antigenic changes depend on extent of change
(more change usually means larger impact)
 Antigenic drift
 in 2002-2003, A/Panama/2007/99 (H3N2) virus was
dominant
 A/Fujian/411/2002 (H3N2) appeared in late 2003 and
caused widespread illness in 2003-2004
Influenza Antigenic Changes
 Antigenic Shift
 major change, new subtype
 caused by exchange of gene segments
 may result in pandemic
 Example of antigenic shift
 H2N2 virus circulated in 1957-1967
 H3N2 virus appeared in 1968 and completely
replaced H2N2 virus
Influenza Type A Antigenic Shifts
Year
1889
1918
1957
1968
1977
Subtype
H3N2
H1N1
H2N2
H3N2
H1N1
Severity of
Pandemic
Moderate
Severe
Severe
Moderate
Mild
Possible Pathways for Generation of
Pandemic
Influenza
Viruses
Avian
Avian
reassortant
virus
virus
Avian
virus
Reassortment
in swine
Human
virus
Reassortment
in humans
Avian-human
pandemic
reassortant virus
Triple Reassortant Swine Influenza A (H1)
Viruses in Humans, U.S., Dec 2005- Feb 2009


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11 sporadic cases of infections in humans
Age range 16 months – 48 years (median 10 years)
Incubation period 3 – 9 days
Symptoms fever (90%), cough (100%), headache
(60%) and diarrhea (30%)
 All recovered
 9 cases had exposure to pigs
 One suspected case of human to human
transmission
Shinde V et al., NEJM 2009:361
Novel Influenza A Virus Infections
 Novel influenza A virus infections are human infections
with influenza A virus subtypes that are different from the
currently circulating human subtypes (A/H1 and A/H3)
Swine origin influenza
virus (S-OIV) infection in
humans is a novel
influenza A virus
infection
Novel Influenza, U.S., 2009
 April 17, 2009, 2 children in
Counties in Southern
California with febrile
respiratory illnesses
confirmed to be a swine
influenza A H1N1 virus
infections
 No contact with pigs
 No links between the 2 cases
 Source of infection unknown
 MMWR dispatch April 21st
Novel Influenza, U.S., 2009
 April 24th, 6 additional cases
reported from southern CA and
TX including 2 cases in the same
family
 Outbreaks of severe respiratory
disease and deaths in Mexico
reported due to the same
influenza virus
 April 26th: Public health
emergency declared DHHS
United States, March 28--May 4, 2009
Number of confirmed (N = 394)* and
probable (N = 414) cases of novel
influenza A (H1N1) virus infection
with known dates of illness onset
Mexico, March 11--May 3, 2009
Number of confirmed (N = 822) and
Suspected (N = 11,356) cases of novel
influenza A (H1N1) virus infection
with known dates of illness onset
MMWR May 8th, 2009
MMWR May 8th, 2009
http://content.nejm.org/cgi/content/full/NEJMoa0903810?query=TOC
www.cdc.gov/H1N1flu
 Comparison of H1N1 Swine
genotypes
 Novel Influenza A H1N1
(quadruple reassortant) virus
 Triple reassortant swine virus
 Novel Influenza A H1N1 contains
genes from:
 North American swine lineage
 Eurasian swine lineage
 Avian, North American
lineage
 Seasonal H3N2
www.cdc.gov/H1N1flu
Swine Flu investigation team
NEJM May 7, 2009
Clinical Symptoms (N=354 Confirmed Cases)
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Fever (94%)
Cough (92%)
Sore throat (66%)
Diarrhea (25%)
Vomiting (25%)
Dawood FS et al., NEJM 2009:361 (May 7)
Age Distribution of Confirmed Cases
(N=532)
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
< 5 years
5-9 years
10-19 years
19-50 years
≥ 51 years
Dawood FS et al., NEJM 2009:361 (May 7)
18%
12%
40%
35%
5%
The Lancet: Volume 373, Issue 9674, Page 1495 (2 May 2009-8 May 2009)
www.cdc.gov/H1N1flu
Surveillance Transition
 State reporting
 From line list to aggregate reporting
Total cases, deaths, hospitalizations
 Population-based surveillance using existing
surveillance systems
 Laboratory
 State confirmation testing of novel H1N1
Guidance to PH lab clinicians has been distributed
 CDC is focusing on validation of state lab testing and
viral isolation and genetic testing
U.S. Human Cases of H1N1 Flu Infection
 As Of May 26, 2009
 6,764 cases, 10 deaths in 48 states including DC
 http://www.cdc.gov/h1n1flu/update.htm
Percentage of Visits for ILI Reported by the U.S.
Outpatient ILI Surveillance Network (ILINet)
ILINet Data by Region
Ongoing and Current Seasonal Influenza
Surveillance – Mortality 122 U.S. Cities
Pandemic Alert Status
WHO
Phase
USG
Stage
CDC
Interval
Inter-Pandemic
1
Pandemic Alert Period
2
3
Pandemic Period
4
5
6
Animal Outbreak
Suspected Human
Outbreak Overseas
Confirmed Human
Outbreak Overseas
Widespread
Outbreaks
Overseas
First Human
Case in N.A.
Spread Throughout United States
Recovery
0
1
2
3
4
5
6
Investigation
Recognition
Initiation
Accel
Peak
Decel
Resolution
Pandemic Severity Index?
Mexico estimate 0.4% (0.3% - 1.5%)
Fraser C et al, Science Express 11 May 2009
US: estimate of true # cases?
Using reported cases and deaths, CFR = 0.15%
If 1/10 cases confirmed/reported, CFR = 0.02%
Epidemiology/Surveillance
Novel Influenza A (H1N1) - 21 May 2009 1100 EDT
U.S. WHO/NREVSS Collaborating Laboratories Summary, 2008-09
A(H1N1-Sw ine)
50
A(Could not be subtyped)
Number of Positive Specimens
3000
32%*
A(H1)
A(Unknow n)
2500
46
43%*
A(H3)
B
* Percentage of all positive influenza
specimens that are Novel Influenza
A(H1N1) or Influenza A (unable to
subtype) for the week indicated
42
38
34
Percent Positive
30
2000
26
22
1500
18
73%*
14
1000
10
6
500
2
Week ending
8/8
8/2
2
7/1
1
7/2
5
6/1
3
6/2
7
5/1
6
5/3
0
4/1
8
5/2
3/2
1
4/4
2/2
1
3/7
1/2
4
2/7
-2
11
/1
11
/15
11
/29
12
/13
12
/27
1/1
0
10
/4
10
/18
0
Percent Positive
3500
Anti-viral Resistance
www.cdc.gov/H1N1flu
Recent Publications
CDC Goals and Interim Guidance related
to Novel Influenza A H1N1
 Goals: prevent transmission and reduce disease
severity
 Guidance documents:
 Surveillance case definitions, laboratory testing
 Schools, colleges, and universities
 Pregnant and breastfeeding women
 Travel industry
 Emergency personnel
 Clinician guidance for patients and specific audiences
 Infection control guidance for healthcare facilities
 Correctional and detention facilities
Laboratory Testing
 Real-time PCR assay to detect seasonal influenza A, B, H1,
H3 and avian H5 serotypes is approved by FDA and
distributed in December 2008 to U.S’s public health
laboratories and WHO’s global influenza surveillance
network
 CDC has developed primers and probes specific for swine
influenza (H1 and H3 subtypes) – protocol available at CDC
website
 Under Project BioShield act of 2004, FDA has issued an
emergency use authorization, allowing the use of this assay
by state public health laboratories
Preventive Measures
 Cover your nose and mouth with a tissue
when you cough or sneeze
 Throw the tissue in the trash after you use it
 Wash your hands often with soap and water,
especially after you cough or sneeze.
Alcohol-based hand cleaners are also
effective
 Avoid close contact with sick people
 Avoid touching your eyes, nose or mouth.
Germs spread this way
 If you get influenza-like illness symptoms,
stay home from work or school except to
seek medical care and limit contact with
others to keep from infecting them
How Influenza Viruses Are Thought To Be
Spread
 Probably through respiratory
droplets:
 Coughing
 Sneezing
 Touching respiratory droplets on
self, another person, or an
object, then touching mucus
membranes (e.g., mouth, nose,
eyes) without washing hands
 Droplet nuclei (airborne
transmission) may also occur
Length of Contagiousness
 Likely similar to seasonal influenza viruses but data
are needed
 One day before ill person develops symptoms to
up to 7 days after they get sick
 Children may shed virus for longer periods
Guidance for Sick Persons
If you are sick, you
should stay home and
avoid contact with
other people as much
as possible.
If you get sick and
experience any of
these warning signs,
seek emergency
medical care.
Warning Signs in Children:
• Fast breathing or trouble breathing
• Bluish skin color
• Not drinking enough fluids
• Not waking up or not interacting
• Irritable, the child does not want to be held
• Flu-like symptoms improve but then return
with fever and worse cough
• Fever with a rash
Warning Signs in Adults:
• Difficulty breathing or shortness of breath
• Pain or pressure in the chest or abdomen
• Sudden dizziness
• Confusion
• Severe or persistent vomiting
Interim CDC Guidance for Institutions of Higher
Education (May 11, 2009)
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CDC is not currently recommending that institutions cancel or dismiss classes or
other large gatherings
If confirmed cases of novel influenza A (H1N1) virus infection or a large number
of cases of influenza like illness (ILI) (i.e. fever with either cough or sore throat)
occur among students, faculty, or staff or in the community, institutions officials
should consult with state and local health officials regarding an appropriate
response
Because the spread of novel influenza A (H1N1) within a health professions
school may pose special concerns, school administrators are strongly
encouraged to contact their state and local public health authorities if they
suspect that cases of ILI are present on their campuses
Students, faculty or staff who live either on or off campus and who have ILI
should self-isolate (i.e., stay away from others) in their dorm room or home for 7
days after the onset of illness or at least 24 hours after symptoms have resolved,
whichever is longer
If possible, persons with ILI who wish to seek medical care should contact their
health care provider or campus health services to report illness by telephone or
other remote means before seeking care. Institutions should assure that all
students, faculty and staff receive messages about what they should do if they
become ill with ILI, including reporting ILI to health services
Interim CDC Guidance for Institutions of Higher
Education (May 11, 2009)
 If persons with ILI must leave their home or dorm room (for example, to seek
medical care or other necessities) they should cover their nose and mouth
when coughing or sneezing. A surgical loose-fitting mask can be helpful for
persons who have access to these, but a tissue or other covering is
appropriate as well. (See Interim Guidance for H1N1 Flu (Swine Flu): Taking
Care of a Sick Person in Your Home)
 Roommates, household members, or those caring for an ill person should
follow guidance developed for caring for sick persons at home. (See Interim
Guidance for H1N1 Flu (Swine Flu): Taking Care of a Sick Person in Your
Home)
 Persons who are at high risk of complications from novel influenza A (H1N1)
infection (for example, persons with certain chronic medical conditions,
children less than 5 years, persons 65 years or older, and pregnant women)
should consider their risk of exposure to novel influenza if they attend public
gatherings in communities where novel influenza A virus is circulating. In
communities with several reported cases of novel influenza A (H1N1) virus
infection, persons who are at risk of complications from influenza should
consider staying away from public gatherings
Groups at Higher Risk for Severe Illness from
Novel Influenza A (H1N1) Infection
 Children younger than 5 years old
 Persons aged 65 years or older
 Children and adolescents (younger than 18 years) who are receiving
long-term aspirin therapy and who might be at risk for experiencing Reye
syndrome after influenza virus infection
 Pregnant women
 Adults and children who have pulmonary, including asthma,
cardiovascular, hepatic, hematological, neurologic, neuromuscular, or
metabolic disorders such as diabetes
 Adults and children who have immunosuppression (including
immunosuppression caused by medications or by HIV)
 Residents of nursing homes and other chronic-care facilities
Interim CDC Guidance for Institutions of Higher
Education: Large Gatherings
 Institutions should encourage persons with ILI to
stay home and away from large gatherings
 Persons who are sick should be instructed to:
 limit their contact with other people as much as
possible and to stay home for 7 days after their
symptoms begin or until they have been
symptom-free for 24 hours, whichever is longer
 use appropriate respiratory and hand hygiene
CDC Interim Guidance for Institutions of Higher
Learning (cont.)
Institutions should consider the following in preparation for possible outbreaks
of novel influenza A (H1N1):
 Establishing a relationship with their state and local health departments
 Keeping informed regarding the evolving situation through regular visits
to the CDC's H1N1 Flu web site
 Developing educational messages in a variety of formats regarding the
illness and how to reduce the spread of influenza. (See H1N1 Flu and
You)
 Alternative educational delivery such as distance learning, web-based
learning, or other ways to increase social distancing
 Planning for assistance for students with ILI, including provision for
meals, medications, and other care
 Developing contingency plans for how to reduce exposure of non-ill
students, staff and faculty to ill students, staff and faculty
Recommendations for Treatment with
Anti-viral Medications
 All hospitalized patients with confirmed, probable or
suspected novel influenza (H1N1)
 Patients who are at higher risk for seasonal
influenza complications
Note: SNS deployed antiviral medications to all states
Recommendations for Post-exposure
Antiviral Prophylaxis
 Close contacts of cases (confirmed, probable, or suspected)
who are at high-risk for complications of influenza
 Health care personnel, public health workers, or first
responders who have had a recognized, unprotected close
contact exposure to a person with novel (H1N1) influenza
virus infection (confirmed, probable, or suspected) during
that person’s infectious period
Recommendations for Outbreak Control
Pandemic Influenza Vaccine?
 Steps for preparing for potential commercial scale
production of a pandemic vaccine
 Under pandemic flu preparedness contracts, HHS
has allocated $1 billion for clinical vaccine studies,
and supplies of bulk vaccine antigen and adjuvant
 Decisions pending on possible use
Seasonal Influenza Vaccine?
 Anticipated that vaccine production will proceed as
planned using the 3 vaccine strains recommended
by WHO
What May Lie Ahead?
Miller MA et al., NEJM 2009:361 (May 7)
Summary
 A novel influenza A H1N1 virus emerged in the U.S.
and globally in spring 2009
 CDC, WHO and public health officials worldwide are
carefully monitoring the situation
 Recommendations should be followed for slowing
the spread of influenza
 For the most current information on the novel H1N1
influenza outbreak: http://www.cdc.gov/h1n1flu/
Resources
 http://www.cdc.gov/h1n1flu/
 http://www.pandemicflu.gov/
 http://www.who.int/csr/disease/swineflu/en/index.html
* Current and archived MMWR publications are available at:
http://www.cdc.gov/mmwr/
Acknowledgements
Influenza Division, CDC
Dr. Dan Jernigan
Dr. Lyn Finelli
Dr. Carolyn Bridges
Dr. Tony Fiore
EOC Joint Information Center (JIC), CDC
Benjamin Hayes, Curt Shannon
Beth Stover