Vaccines and Therapeutics

On this earth there are plagues and there are victims, and it’s up to us, as much as possible, not to join forces with the plagues. – Albert Camus, The Plague, 1946

Vaccines

Animal Vaccines

At the present, only one vaccine has been conditionally approved for use in poultry in the United States (Cohen 2025). The vaccine is produced by Zoetis and it contains a killed version of the H5N2 variant of the influenza virus.

Human Vaccines

Reproduced from Taaffe et al. (2025)

Manufacturer Location Vaccine name Subtype Vaccine type Adjuvant Age group indication Licensing authority
AstraZeneca UK Pandemic influenza vaccine H5N1 AstraZeneca H5N1 LAIV, egg based None Children† EMA
Denka Seiken Japan Adsorbed influenza vaccine (H5N1) “Seiken” H5N1 IIV, egg based Aluminium-based Information unavailable PMDA
GC Biopharma South Korea GCFLU H5N1 H5N1 IIV, egg based Aluminium-based Healthy adults MFDS
GlaxoSmithKline UK Adjupanrix H5N1 IIV, egg based AS03 Healthy adults, children, older adults EMA
GlaxoSmithKline UK Q Pan/Influenza A (H5N1) virus monovalent vaccine, adjuvanted H5N1 IIV, egg based AS03 Healthy adults, children, older adults FDA
Daiichi Sankyo Japan Adsorbed cell culture-derived influenza vaccine H5N1 H5N1 IIV, cell based Aluminium-based Healthy adults, children, older adults PMDA
Daiichi Sankyo Japan Adsorbed influenza vaccine (H5N1) “HOKKEN” H5N1 IIV, egg based Aluminium-based Healthy adults PMDA
KM Biologics Japan Emulsion-adjuvanted cell-culture derived influenza HA vaccine H5N1 IIV, cell based AS03 Healthy adults PMDA
Sanofi Pasteur France Influenza virus vaccine, H5N1 H5N1 IIV, egg based None Healthy adults FDA
CSL Seqirus Australia Audenz H5N1 IIV, cell based MF59 Healthy adults, children, older adults FDA
CSL Seqirus Australia Foclivia H5N1 IIV, egg based MF59 Healthy adults, children, older adults EMA
CSL Seqirus Australia Panvax H5N1 influenza vaccine H5N1 IIV, unknown Information unavailable Information unavailable TGA
CSL Seqirus Australia Celldemic H5N1 IIV, cell based MF59 Healthy adults, children, older adults TGA/EMA
CSL Seqirus Australia Incellipan H5N1 IIV, cell based MF59 Healthy adults, children, older adults EMA
CSL Seqirus Australia Zoonotic influenza vaccine, Seqirus H5N8 IIV, egg based MF59 Healthy adults, older adults EMA
CSL Seqirus Australia Panvax H5N8 influenza vaccine H5N8 IIV, egg based Aluminium-based Healthy adults, children, older adults TGA
CSL Seqirus Australia Aflunov H5N1 IIV, egg based MF59 Healthy adults, children, older adults TGA/EMA
Sinovac Biotech China Panflu H5N1 IIV, egg based Aluminium-based Healthy adults SFDA
Takeda Pharmaceutical Japan Cell cultured influenza vaccine (H5N1) “TAKEDA” H5N1 IIV, cell based None Information unavailable PMDA
The Research Foundation for Microbial Diseases for Osaka University Japan Adsorbed influenza vaccine (H5N1) “BIKEN” H5N1 IIV, egg based Aluminium-based Healthy adults PMDA

Therapeutics

Therapeutics for viral infections are generally used after an infection occurs. We know that the human or the the animal host has been infected, and we can use therapeutics such as antivirals or monoclonal antibodies to treat the infection and reduce the severity of the disease (i.e., duration of illness, mortality, etc.).

Antivirals

There are currently four FDA approved antivirals for the treatment of influenza in humans.

  • oseltamivir (also known as Tamiflu)
  • zanamivir
  • peramivir
  • baloxavir

Antivirals interfere with the ability of the virus to replicate in the infected individual. For example oseltamivir is a neuraminidase inhibitor. The flu’s neuraminidase enzyme is responsible for cleaving the sugar molecules (sialic acid) that form the backbone of the viral envelope, and instead of binding to the sialic acid, oseltamivir binds to the enzyme and inhibits its activity. Antiviral are not without risk as some carry side effects such as nausea, vomiting, diarrhea, and headache. Additionally, antivirals add selective pressure to the virus population in the host which can lead to the emergence of antivirual resistant viruses which can be transmitted to other hosts and make antiviruals less effective. This has been seen sporadically with H5N1 (McKimm‐Breschkin 2013).

Monoclonal Antibodies

Monoclonal antibodies are antibodies that are produced in pharamaceutical laboratories rather than being produced by the host’s immune system. They are designed to target a specific antigen and are used to treat a variety of diseases including cancer and viral infections. Unfortunately, no licensed monoclonal antibodies have been approved for the treatment of influenza–though there are groups actively working on developing them (Lederhofer et al. 2024). This is due to a multitude of reasons, mainly that the influenza virus is constant under going changes through mutation, recombination, and antigenic drift.

References

Cohen, Jon. 2025. “U.s. Conditionally Approves Vaccine to Protect Poultry from Avian Flu.” Science, February. https://www.science.org/content/article/u-s-conditionally-approves-vaccine-protect-poultry-avian-flu.
Lederhofer, Julia, Yaroslav Tsybovsky, Lam Nguyen, Julie E. Raab, Adrian Creanga, Tyler Stephens, Rebecca A. Gillespie, et al. 2024. “Protective Human Monoclonal Antibodies Target Conserved Sites of Vulnerability on the Underside of Influenza Virus Neuraminidase.” Immunity 57 (3): 574–586.e7. https://doi.org/10.1016/j.immuni.2024.02.003.
McKimm‐Breschkin, Jennifer L. 2013. “Influenza Neuraminidase Inhibitors: Antiviral Action and Mechanisms of Resistance.” Influenza and Other Respiratory Viruses 7 (Suppl 1): 25–36. https://doi.org/10.1111/irv.12047.
Taaffe, Jessica, Shuyi Zhong, Shoshanna Goldin, Kate S. Rawlings, Benjamin J. Cowling, and Wenqing Zhang. 2025. “An Overview of Influenza H5 Vaccines.” The Lancet Respiratory Medicine 0 (0). https://doi.org/10.1016/S2213-2600(25)00052-9.