Centers for Disease Control and Prevention
Office of Communications
Update on Highly Pathogenic Avian Influenza A(H5N1)
Virus for Clinicians and Healthcare Centers
Clinician Outreach and Communication Activity (COCA) Call
Tuesday, July 16, 2024
Free Continuing Education
▪ Free continuing education is offered for this webinar.
▪ Instructions for how to earn continuing education will be provided at the
end of the call.
Continuing Education Disclosure
▪ In compliance with continuing education requirements, all planners, presenters, and moderators
must disclose all financial relationships, in any amount, with ineligible companies over the previous
24 months as well as any use of unlabeled product(s) or products under investigational use.
▪ CDC, our planners, and presenters/moderators wish to disclose they have no financial
relationship(s) with ineligible companies whose primary business is producing, marketing, selling,
re-selling, or distributing healthcare products used by or on patients.
▪ Content will not include any discussion of the unlabeled use of a product or a product under
investigational use with the exception of Dr. Tim Uyeki who will discuss using oseltamivir at higher
dosing for post-exposure prophylaxis than for controlling seasonal influenza.
▪ CDC did not accept financial or in-kind support from ineligible companies for this continuing
education.
Objectives
At the conclusion of today’s session, the participant will be able to
accomplish the following:
1. Discuss the epidemiology and clinical features of human cases of HPAI
A(H5N1) virus infection.
2. Describe risk of human infection with HPAI A(H5N1) viruses, identify
higher risk populations, and what to assess in clinical settings.
3. Describe testing, using antivirals, and infection prevention and control
recommendations for patients with HPAI A(H5N1) virus infection.
To Ask a Question
▪ Using the Zoom Webinar System
– Click on the “Q&A” button
– Type your question in the “Q&A” box
– Submit your question
▪ If you are a patient, please refer your question to your healthcare provider.
▪ If you are a member of the media, please direct your questions to CDC
Media Relations at 404-639-3286 or email [email protected].
Today’s Presenters
Tim Uyeki, MD, MPH, MPP
Chief Medical Officer
Influenza Division
National Center for Immunization and Respiratory Diseases
Centers for Disease Control and Prevention
Ryan Fagan, MD, MPH&TM
Medical Officer
Prevention and Response Branch
Division of Healthcare Quality Promotion
National Center for Emerging and Zoonotic Infectious Diseases
Centers for Disease Control and Prevention
Alicia Budd, MPH
Team Lead, National Surveillance and Outbreak Response Team
Epidemiology and Prevention Branch
Influenza Division
National Center for Immunization and Respiratory Diseases
Centers for Disease Control and Prevention
Highly Pathogenic
Avian Influenza
A(H5N1) Virus
Tim Uyeki, MD, MPH, MPP
Chief Medical Officer, Influenza Division
National Center for Immunization and Respiratory
Diseases
Centers for Disease Control and Prevention
July 16, 2024
• HPAI A(H5N1) virus first detected in a poultry outbreak in
Scotland (1959)
▪ Infect respiratory and gastrointestinal tracts of birds
▪ High mortality in infected poultry
▪ Continue to evolve (classified into virus clades)
• Clade 2.3.4.4b viruses emerged in 2020 in wild birds
▪ Unprecedented wide global spread
▪ Many bird species infected, poultry outbreaks
▪ Many terrestrial and marine mammals infected (often fatal)
▪ Detected in wild birds in North America (end of 2021)
▪ Poultry outbreaks, wild bird detections since 2022 (ongoing)
▪ >99 million commercial poultry/backyard birds affected (48 states)
▪ >9500 wild birds (50 states or territories)
▪ 2024: Livestock (goats, dairy cattle)
Overview of Highly Pathogenic Avian Influenza (HPAI) A(H5N1) virus
• HPAI A(H5N1) viruses bind preferentially to receptors most prevalent in the human
lower respiratory tract
▪ Virus receptors are also found on conjunctivae
• First human infections identified in 1997 (Hong Kong)
▪ 18 cases, 6 deaths
• 1997 to date: 919 human cases reported (24 countries)*
▪ 51% case fatality proportion
Human Infections with HPAI A(H5N1) Viruses
*Includes some A(H5)+, presumed H5N1 cases
HPAI A(H5N1) Cases Since 1997*
2022-2024: 36 cases
(Australia 1, Cambodia 13, Chile 1, China 2,
Ecuador 1, Spain 2, UK 5, US 9, Vietnam 2)
*Includes some A(H5)+, presumed H5N1 cases
➢Unprotected exposures (without respiratory or eye
protection)
▪ Poultry exposures
▪ Direct/close contact with sick/dead poultry
▪ Visiting a live poultry market
▪ Exposure to other infected animals
▪ Direct contact or close exposure (swans,
dairy cows)
▪ Limited, non-sustained human-to-human
transmission from prolonged exposure to a
symptomatic H5N1 patient (last reported 2007)
Human Infections with HPAI A(H5N1) Viruses
▪ Human cases (n=9)
▪ Associated with poultry exposures: 5 (H5N1: 2; H5: 3)
▪ April 2022: 1 case reported fatigue while depopulating poultry (CO)
▪ July 2024: 4 cases in poultry workers performing poultry depopulation (CO)
▪ All cases were clinically mild, not hospitalized
▪ Associated with dairy cattle exposures: 4 (H5N1: 3; H5: 1)
▪ March - July 2024: 4 cases in dairy farm workers (TX, MI, CO)
▪ All cases were clinically mild, not hospitalized
HPAI A(H5) Cases, U.S. 2022-2024
Clinical findings in mild illness:
▪ Fever or feverishness, nonproductive cough, muscle
aches, malaise, headache, sore throat, myalgia
▪ Abdominal pain; vomiting and diarrhea can occur
▪ Eye discomfort/redness/eye discharge (conjunctivitis)
alone is uncommon but can occur
Progression to lower respiratory tract disease (5-7 days
after symptom onset): difficulty breathing, shortness of
breath, chest pain, tachypnea
▪ Hospital admission findings:
▪ Clinical: hypoxia, signs of pneumonia
▪ Laboratory: leukopenia, lymphopenia, mild-to-moderate
thrombocytopenia
▪ Radiographic findings: patchy, interstitial, lobar, and/or
diffuse infiltrates and opacities, consolidation
Signs and Symptoms of HPAI A(H5N1) Virus Infection
▪ Pneumonia is the most common complication
▪ Progression to respiratory failure, ARDS
▪ Community-acquired bacterial co-infection is rare; ventilator associated
pneumonia in intubated patients
▪ Other complications
▪ Acute kidney injury
▪ Sepsis, shock, DIC, multi-organ failure (respiratory & renal failure)
▪ Cardiac failure
▪ Atypical complications
▪ Encephalitis, meningoencephalitis
▪ Reye syndrome with salicylate exposure
▪ Spontaneous miscarriage in a pregnant woman
Clinical Complications of HPAI A(H5N1) Virus Infection
• People with close, prolonged, or unprotected exposures to infected animals
(including livestock), or to environments contaminated by infected animals, are at
greater risk of infection
• Potential occupationally exposed persons
▪ Dairy farm workers
▪ Slaughterhouse workers
▪ Milk processing facility employees
▪ Poultry workers
▪ Veterinarians, veterinary assistants
• Unprotected exposure to a symptomatic person with H5N1 virus infection
Potential Exposures to H5N1 Virus
• Monitor for signs or symptoms of acute
respiratory illness and/or conjunctivitis and seek
clinical care if signs/symptoms occur
(testing, potential antiviral treatment)
• If A(H5N1) virus infection is suspected (use recommended PPE*):
▪ Patients with acute respiratory symptoms:
› Collect (1) a nasopharyngeal swab, and (2) a combined nasal and throat swab specimen
» Place each specimen into separate tubes of viral transport media
▪ Patients with conjunctivitis:
› Collect (1) a conjunctival swab, and (2) a nasopharyngeal swab
» Place each specimen into separate tubes of viral transport media
➢ Influenza A virus, and A(H5) virus testing must be done at a public health laboratory
Influenza tests available in clinical settings
▪ Cannot specifically identify A(H5N1) virus
▪ Cannot differentiate A(H5N1) virus from seasonal influenza A(H3N2) and A(H1N1)pdm09 viruses
▪ Need to perform subtyping of influenza A viruses (H1, H3), and A(H5) assays
*PPE: NIOSH approved N95 filtering facepiece respirator, eye protection, gown, gloves
Influenza Testing (Outpatients)
• Patients with lower respiratory tract disease (use recommended PPE*)
▪ Collect upper respiratory specimens (NP swab, combined nasal & throat swabs),
and sputum for influenza A and A(H5) virus testing at public health laboratories
▪ Intubated patients: Also collect endotracheal aspirate specimens (or BAL fluid)
➢ Collect multiple respiratory specimens from different sites on multiple days for
patients with suspected HPAI A(H5N1) virus infection to maximize potential for
diagnosis
*PPE: NIOSH approved N95 filtering facepiece respirator, eye protection, gown, gloves
Influenza Testing (Hospitalized Patients)
• If A(H5N1) virus infection is suspected
▪ Start empiric antiviral treatment with oseltamivir as soon as possible
(while awaiting results)
▪ Recommend home isolation for mild illness, notify local and state public health
for testing, monitoring and follow-up as soon as possible
▪ If A(H5N1) virus infection is confirmed: home isolation
▪ Consider: until clinically improved and repeat respiratory specimens are
negative for influenza
▪ Post-exposure antiviral prophylaxis
▪ If A(H5N1) virus infection is confirmed, household and other close contacts are
recommended to receive oseltamivir at treatment dosing as soon as possible
(twice daily x 5 days; longer duration for ongoing exposures)
» Monitor for any illness signs/symptoms x 10 days after the last exposure
Antiviral Treatment and Prophylaxis
• Isolate patients, follow recommended infection prevention and control
measures, use recommended PPE
• Oseltamivir treatment
• Supportive care of complications
▪ Advanced organ support, critical care
• Immunomodulators
▪ Avoid moderate to high-dose corticosteroids
› Associated with prolonged viral shedding
› May increase risk for ventilator-associated pneumonia and death
▪ No data for other immunomodulators (e.g., IL-6 receptor blockers, JAK
inhibitors)
Clinical Management: Hospitalized Patients
HPAI A(H5N1) in Dairy Cattle: Current
Situation and Response Updates
HPAI A(H5N1) in U.S Dairy Herds
Highly Pathogenic Avian Influenza (HPAI) Detections in Livestock; WAHIS (woah.org)
21
• Since March 2024: USDA has
confirmed A(H5N1) virus infections
of dairy herds in >155 farms (13 states)
▪ Clade 2.3.4.4b virus
▪ High levels of virus in raw milk
• Other animal species reported in
association with infected dairy herds in
the U.S. include:
▪ Wild birds, cats, racoons, opossums
A(H5) Human Cases related to
Dairy Cow Exposure
• 4 human cases identified to date (H5N1: 3)
▪ Late March/early April: Texas: 1 case
▪ May: Michigan: 2 cases
▪ July: Colorado: 1 case
• Adult dairy farm workers in contact with
cows, all with clinically mild illness
➢ Not wearing recommended PPE (no respiratory or eye
protection)
▪ 3 cases with conjunctivitis only, 1 case with acute
respiratory symptoms
▪ All offered oseltamivir, and recovered without
hospitalization
▪ No human-to-human transmission
* Health Alert: First Case of Novel Influenza A (H5N1) in Texas, March 2024 | Texas DSHS
†
Influenza A (H5N1) (michigan.gov)
CDC Recommendations on Raw Milk
• A(H5N1) virus has been detected in raw cow
milk of infected cows.
• Pasteurization kills A(H5N1) viruses and
pasteurized milk is safe to drink.
• People should not drink raw milk or consume
products made from raw milk.
• CDC recommends against consuming raw milk
contaminated with live A(H5N1) virus as a
way to develop antibodies against A(H5N1)
virus to protect against future disease.
https://www.cdc.gov/food-safety/foods/raw-milk.html
Self-knowledge Check: What are possible signs and
symptoms of HPAI A(H5N1) Virus Infection in humans?
A. Nonproductive cough
B. Conjunctivitis
C. Fever
D. Signs of pneumonia
E. A and B only
F. All of the Above
Self-knowledge Check: What are possible signs and
symptoms of an HPAI A(H5N1) Virus Infection in humans?
A. Nonproductive cough
B. Conjunctivitis
C. Fever
D. Signs of pneumonia
E. A and B only
F. All of the Above
Rationale: Based on past clinical and hospital admission findings, these are all
signs and symptoms observed in patients with H5N1 virus infection.
HPAI A(H5N1) Virus
Healthcare Infection Prevention and Control
Ryan Fagan, MD, MPH&TM
July 16, 2024
CDC Division of Healthcare Quality Promotion
• Historically high morbidity and mortality associated with H5N1 virus
infections
• Extremely low population immunity to H5N1 viruses
• Opportunities for viral mutations and adaptation
• No H5N1 vaccines currently available
• CDC Interim Guidance for Infection Control in Healthcare Settings for Novel Influenza A
Viruses Associated with Severe Disease: https://www.cdc.gov/bird-flu/hcp/novel-flu-
infection-control/?CDC_AAref_Val=https://www.cdc.gov/flu/avianflu/novel-flu-infection-
control.htm
Rationale for CDC Interim Healthcare Infection Control
Guidance for HPAI A(H5N1)
• Patient placement in airborne infection isolation room
• Personal protective equipment for healthcare personnel: gloves, gown, eye
protection, and respiratory protection at least as protective as N95 filtering
facepiece respirator
• Source control
• Additional standard precautions
- Standard cleaning, disinfection, laundry, and food service procedures
- Respiratory hygiene and cough etiquette
• Follow local medical waste regulations
Selected Recommendations from Interim Guidance for
Patients with HPAI A(H5N1) Virus Infections
Self-knowledge Check: Which of these is recommended
for patients with suspected or confirmed HPAI A (H5N1)
infection?
A. Patient placement in AIIR room
B. Personal protective equipment for healthcare personnel: gloves, gown, eye
protection, and respiratory protection at least as protective as N95 filtering
facepiece respirator
C. Source control
D. Follow local medical waste regulations
E. All of the above
Self-knowledge Check: Which of these is recommended
for patients with suspected or confirmed HPAI A (H5N1)
infection?
A. Patient placement in AIIR room
B. Personal protective equipment for healthcare personnel: gloves, gown, eye
protection, and respiratory protection at least as protective as N95 filtering
facepiece respirator
C. Source control
D. Follow local medical waste regulations
E. All of the above
Rationale: All of the options are recommended for patients with suspected or
confirmed HPAI A (H5N1) infection.
Highly Pathogenic
Avian Influenza
A(H5N1) Virus:
Surveillance and
Monitoring
Alicia Budd, MPH
Centers for Disease Control and
Prevention
July 16, 2024
CDC’s Priorities
• Supporting and engaging public
health and agricultural partners
• Protecting human health and
safety
• Understanding risk to people
from HPAI A(H5N1) viruses
• Assessing HPAI A(H5N1) viruses
for genetic changes
Monitoring of Exposed Persons
• Since February 2022
o Active monitoring of people exposed to
infected birds, poultry or
other animals for 10 days after exposure
▪ >9,500 people
▪ About 350 people tested for influenza A
• Current cattle outbreak (2024)
o >1,390 people monitored
o States and CDC tested >60 persons
https://www.cdc.gov/flu/avianflu/h5-monitoring.html
Summer Influenza Surveillance Priorities
• Provider outreach to continue influenza testing through summer,
particularly for patients with recent history of relevant exposures
• Continued monitoring of people with recent exposure to HPAI A(H5N1)
on confirmed farms
• Facilitate detection of HPAI A(H5N1) human cases in the community
through enhanced, national surveillance at seasonal influenza levels
▪ Subtyping of influenza A positive specimens, expanded specimen sources
▪ Continued surveillance of lab-confirmed influenza associated hospitalizations
through FluSurv-NET
• Continued follow-up for areas that flag in syndromic and wastewater
data
CDC Strategy for Enhanced Summer 2024 Influenza Surveillance | Avian Influenza (Flu)
• Since February 2024, public health laboratory monitoring includes testing of 34,091
specimens using a protocol that would have detected HPAI A(H5N1)
Surveillance, Human Monitoring, and Testing
How CDC is monitoring influenza data among people to better understand the current avian influenza A (H5N1) situation | Bird Flu | CDC, Weekly U.S. Influenza Surveillance Report | CDC
35
No indicators of unusual influenza
activity in people, including avian
influenza A(H5N1)
‘High’ Wastewater Sites and Potential HPAI A(H5N1)
Detections
https://www.cdc.gov/flu/avianflu/h5-monitoring.html
Developed Levels for Influenza A
Virus in Wastewater
• Influenza A Virus Level metric
• Compare current level to levels at
the same site during the 2023-2024
influenza season
• Flag >80th percentile as “High”
• Outreach to state/local partners in
"high" areas, as well as notifying
USDA and FDA through the UCG
Epi WG
Epidemiologic Investigations
• Health and agricultural partners at
local, state and federal level, and
affected farms
• Important public health questions
o Evidence of infection in exposed
populations?
o Spectrum of illness and rate of
asymptomatic infections?
o Types of exposure on farms/dairies?
o Behaviors associated with human infections
or protection from infection?
• Assess risk for symptomatic and
asymptomatic infection and a survey to
assess exposures
Public Health Risk
• Overall, current avian influenza A(H5N1)
human health risk assessment for the
U.S. general public remains low
• Increased risk with exposure to infected
animals or environment – occupational,
recreational
• Exposed individuals should monitor for
symptoms after first exposure and for 10
days after last exposure
• Continued monitoring for influenza
throughout summer months
Highly Pathogenic Avian Influenza A(H5N1) Virus in Animals: Interim
Recommendations for Prevention, Monitoring, and Public Health
Investigations | Avian Influenza (Flu) (cdc.gov)
Resources from CDC
―Situation Updates:
―CDC A(H5N1) Bird Flu Response Update | Avian
Influenza (Flu)
―Surveillance Updates
―How CDC is monitoring influenza data among people
to better understand the current avian influenza A
(H5N1) situation | Avian Influenza (Flu)
―Technical Report
―Technical Report: Highly Pathogenic Avian Influenza
A(H5N1) Viruses | Avian Influenza (Flu) (cdc.gov)
―Updated Recommendations
―Highly Pathogenic Avian Influenza A(H5N1) Virus in
Animals: Interim Recommendations for Prevention,
Monitoring, and Public Health Investigations
―Recommendations for Worker Protection and Use of
Personal Protective Equipment (PPE) to Reduce Exposure
to Novel Influenza A Viruses Associated with Severe
Disease in Humans
A. Is there evidence of infection with HPAI A(H5N1) virus in exposed
populations?
B. If human infections with HPAI A(H5N1) virus are identified, what is the
spectrum of illness?
C. What are possible exposures to HPAI A(H5N1) virus in workers
at farms/dairies?
D. What are potential behaviors associated with human infections with HPAI
A(H5N1) virus or protection from infection?
Self-knowledge Check: True or False: All of these are
important public health questions to consider during
epidemiological investigation
Self-knowledge Check: True or False: All of these are important
public health questions to consider during epidemiological
investigation
A. Is there evidence of infection with HPAI A(H5N1) virus in exposed populations?
B. If human infections with HPAI A(H5N1) virus are identified, what is the spectrum of
illness?
C. What are possible exposures to HPAI A(H5N1) virus in workers at farms/dairies?
D. What are potential behaviors associated with human infections with HPAI A(H5N1)
virus or protection from infection?
Answer: True
Rationale: All of these questions are important to gain understanding of the full scope of infection
and to protect public health.
Thank you
To Ask a Question
▪ Using the Zoom Webinar System
– Click on the “Q&A” button
– Type your question in the “Q&A” box
– Submit your question
▪ If you are a patient, please refer your question to your healthcare provider.
▪ If you are a member of the media, please direct your questions to CDC
Media Relations at 404-639-3286 or email [email protected].
TRAIN
• January 1, 2024: Move from Training and Continuing Education Online (TCEO) to CDC TRAIN
(https://www.train.org/cdctrain).
• Existing Activities: Continue to use TCEO for existing activities that have CE set to expire in 2024,
since these courses will not move to CDC TRAIN. You may also use TCEO for existing activities with
CE set to expire in 2025, before the courses transition to CDC TRAIN sometime next year. If you
begin one of these courses in TCEO, we will let you know when the course will move to CDC
TRAIN.
• Transcripts & Certificates: You can access and download CE transcripts and certificates in TCEO
through the end of 2025.
• Instructions will be available on both platforms and a learner support team will be available to
answer questions.
Continuing Education
• All continuing education for COCA Calls is issued online through CDC TRAIN at CDC
TRAIN (https://www.train.org/cdctrain).
• Those who participate in today’s COCA Call and wish to receive continuing education
please complete the online evaluation by August 19, 2024, with the course code
WC4520R-071624. The registration code is COCA071624.
• Those who will participate in the on-demand activity and wish to receive continuing
education should complete the online evaluation between August 20, 2024, and
August 20, 2026, and use course code WD4520-071624.
Today’s COCA Call will be Available to View On-Demand
• When: A few hours after the live call ends*
• What: Video recording
• Where: On the COCA Call webpage
• https://emergency.cdc.gov/coca/calls/2024/callinfo_071624.asp
*A transcript and closed-captioned video will be available about one week after the live session
For more information, contact CDC
1-800-CDC-INFO (232-4636)
TTY: 1-888-232-6348 www.cdc.gov
The findings and conclusions in this report are those of the authors and do not necessarily represent the official position
of the Centers for Disease Control and Prevention.
Thank you for joining us today!
https://emergency.cdc.gov/coca
