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Influenza A Virus Biological Agent Reference Sheet (BARS)

Last updated 09/11/2023

This BARS covers Influenza A viruses, including High Pathogenic Avian Influenza (HPAI) strains.


Agent Type Risk Group Biosafety Level Animal Housing Biosafety Level
Virus  RG-2 BSL-2



Agent Characteristics

Risk Group: RG-2 associated with human disease, rarely serious; preventive, or therapeutic interventions often available.

Agent Type: Virus 

Description: Influenza A viruses are segmented, negative sense, single-stranded RNA viruses in the Orthomyxoviridae family. Influenza A viruses are divided based on the nature of the glycoproteins present on the envelope, haemagglutinin (HA) and neuraminidase (NA). Variation in the surface antigens allows Influenza A viruses to have a broad host range, including humans and other animals. Only three of the 16 HA subtypes (H1, H2, and H3) and two of the 9 NA subtypes (N1 and N2) have established stable human lineages since the 1918 pandemic. Pandemics, epidemics, localized outbreaks, and sporadic cases have been caused by influenza A viruses, including High Pathogenic Avian Influenza (HPAI) strains. While many strains produce mild symptoms such as headache, sore throat, cough, and sneezing, at-risk populations can experience pulmonary complications, myocarditis, and pericarditis. Secondary bacterial pneumonia after influenza is one of the leading causes of mortality worldwide.

Host Range: Includes avian, swine, and primates, including humans, and can be broader depending on strain.

Host Shedding: Blood, saliva, feces

Route of Exposure to Humans: Aerosol/inhalation, animal bites, contaminated items, direct contact, mucous membranes, and broken skin

Infectious Dose: 100-1000 viral particles for humans, varies by strain

Incubation Period: 1-7 days

Health Hazards

Signs and symptoms of infection may include:

  • Flu-like symptoms (i.e., fever, headache, dehydration, weight loss, lethargy)
  • Gastrointestinal symptoms (i.e., loss of appetite, nausea, vomiting, diarrhea)
  • Respiratory symptoms (i.e., coughing, sneezing)

Immunizations: Available                             Prophylaxis*: Antiviral drugs available

*Formal medical advice is obtained during medical consultations with Cornell Health or a primary healthcare provider as needed.

Agent Viability

Survival Outside Host Disinfection Inactivation

24 to 48 hours on nonporous surfaces

8 to 12 hours on porous materials

1:10 Bleach Dilution 

70% ethanol

Providone iodine 

Quarternary ammonia 

Boil for 10 minutes

For more guidance on disinfection, see: disinfectant selection.

Laboratory Hazards

  • High-energy-creating activities (centrifugation, sonication, high-pressure systems, vortexing, tube cap popping)
  • Handling of sharps (needles, scalpels, microtome blades, broken glass, etc.)
  • Splash/droplet-creating activities (shaking incubators, liquid culturing, mechanical pipetting)
  • Equipment contamination
  • Exposed skin/uncovered wounds

Laboratory Acquired Infection (LAI) History: Research published in 1997 describes a case in which two people showed signs of infection after exposure to experimentally infected pigs.

Laboratory Handling Guidelines

Laboratory Biosafety Level (BSL): BSL-2 or BSL-3 for highly pathogenic avian influenza.


Lab Engineering Controls Personal Protective Equipment

More Information


  1. David E. Wentworth, Martha W. McGregor, Michael D. Macklin, Veronica Neumann, Virginia S. Hinshaw. Transmission of Swine Influenza Virus to Humans after Exposure to Experimentally Infected Pigs. The Journal of Infectious Diseases,,1997;  175 (1).
  2. Influenza A/H1N1. Biological Agent Reference Sheets.  Pathogen Safety Data Sheets: Infections Substances - Influenza virus type A.
  3. CDC. 2009. Biosafety in Microbiological and Biomedical Laboratories. Center for Disease Control and Prevention.
  4. Influenza virus type A. Pathogen Safety Data Sheet. Public Health Agency of Canada.
  5. Department of Health and Human Services, National Institutes of Health. 2019. NIH Guidelines for Research Involving Recombinant or Synthetic Nucleic Acid Molecules (NIH Guidelines). NIH Office of Science Policy