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Influenza and COVID-19 Clinical Trials & Studies

The flu is a highly contagious disease caused by the influenza virus, and if left unchecked, can lead to severe respiratory conditions and potentially hospitalization.1  

The influenza virus is a highly adaptable virus that mutates continuously.2 As such, vaccines effective for one flu season may not be effective for the next. This means that clinical research and development are constantly ongoing for the next influenza season.3  

COVID-19 is often confused for the flu due to its similar symptoms, but it is a different disease caused by the SARA-CoV-2 virus that gave rise to the COVID-19 pandemic of 2020.4 The race towards the COVID-19 vaccine revolutionized clinical research for coronaviruses and influenza viruses with the development of mRNA vaccines.5 

What are Influenza (Flu) and COVID-19 Clinical Trials?

Influenza and COVID-19 clinical trials are studies where researchers, volunteers and pharmaceutical companies come together and collaborate for the controlled testing of new and innovative treatment or prevention options on volunteer participants.  

Volunteers for clinical trials are shortlisted through a rigorous screening and informed consent process. Data obtained from clinical trials is used as evidence for approval of a treatment by regulatory bodies like the FDA.  

Why is Influenza Vaccine Research Important?

There are around a billion cases of influenza every year, including 3-5 million severe cases globally.1 Influenza vaccination is important at both the individual and the community level. It prevents millions of illnesses and influenza-related doctor visits. It is also important for patients with chronic diseases like COPD to reduce the risk of Influenza-related complications.6

Influenza vaccine (or ‘flu shot’) research and development is a constant seasonal effort by scientists worldwide, as they try to predict the influenza strains which are most likely to be dominant and in circulation the following influenza season and adapt vaccines to counter them.3,7

Healthcare bodies globally have dedicated initiatives for seasonal influenza research. For instance, the CDC (Centers for Disease Control and Prevention) conducts research on how well flu vaccines work every season.8 The WHO (World Health Organization) recognizes seasonal influenza as a healthcare concern, and provides strategic guidance and support for member states against seasonal influenza under the Global Influenza Programme.9

Like most infectious diseases, care for influenza is focused on prevention.3 Influenza vaccines can help protect against potentially serious complications and prevent hospitalization. Therefore, it is important for every eligible person to stay up-to-date on their influenza shots/vaccines.6

Studies are also ongoing to develop vaccinations with a potential broader immunity against the influenza virus which could help protect against several flu strains.10

How is COVID-19 Different From Influenza?

Influenza and COVID-19 are often confused due to similar respiratory symptoms and ways of spreading, but they have different causes. Influenza is caused by the influenza family of viruses, meanwhile COVID-19 is caused by the SARS-CoV-2 virus. From what we know, COVID-19 also appears to spread more easily than influenza.4 

The WHO has been keeping a record of SARS-CoV-2 variants since the COVID-19 pandemic of 2020, and has developed capabilities to track potential variants of concern to guide vaccine development.11,12 

Why is COVID-19 Vaccine Research Important?

The 2020 COVID-19 pandemic presented a challenge for the research community to fast-track the development of coronavirus vaccine candidates.  

Researchers rose to this challenge by accelerating the research and development of the mRNA vaccine technology. This enabled scientists to develop vaccines for different virus variants in a relatively short amount of time.5  

mRNA is a molecule which instructs your cells how to make proteins based on the information stored in genes. An mRNA vaccine tells your cells to make a harmless part of the virus (called an antigen) in the body. The body can then learn to recognize and produce antibodies to fight the real virus.13

mRNA vaccine technology is now being adapted to create vaccines for influenza. Sanofi has collaborated with the Anderson Lab for mRNA vaccine research and accelerated development of new mRNA vaccine candidates and therapies for genetic diseases. All influenza and COVID-19 vaccine candidates can only be made available for the general public after rigorous testing and randomized controlled clinical trials.

Sanofi’s Commitment to Influenza and COVID-19 Vaccine Trials

Sanofi is committed to adapting to the ever-evolving influenza research landscape with clinical trials.

Sanofi’s COVID-19 Vaccine Clinical Research

In May 2024, we collaborated with another company to commercialize a non-mRNA COVID-19 vaccine and accelerate potential for the development of novel flu-COVID combination vaccines.14 In December 2024, two of our influenza-COVID-19 combination vaccine candidates were granted the Fast Track designation by the FDA.15 Two clinical studies were initiated for these candidates shortly after (NCT06695117 and NCT06695130).

Types of Influenza Clinical Research

Influenza clinical research is multidisciplinary, featuring elements of epidemiology, public health and also research in disease pathways.1 Influenza clinical research can be grouped into a few broad pillars: 

  • Vaccine development: development of vaccine candidates for influenza prevention3
  • Epidemiological studies: studies observing the prevalence, impact and demographics of influenza outbreaks3
  • Antiviral studies: antivirals are drugs that disrupt the life cycle of the influenza virus post-infection1,16
  • Diagnostic research: studies looking to increase efficiencies in the influenza screening process17

More information on Sanofi’s Influenza and COVID-19 Clinical Trials and Studies

Find more information on our in-progress and upcoming influenza and COVID-19 clinical trials:

Influenza and COVID-19 clinical trials

References

  1. World Health Organization. Influenza (seasonal). WHO website. Accessed May 21, 2025. https://www.who.int/health-topics/influenza-seasonal#tab=tab_1
  2. Uno N, Ross TM. Multivalent next generation influenza virus vaccines protect against seasonal and pre-pandemic viruses. Sci Rep. 2024;14(1):1440. doi:10.1038/s41598-023-51024-0
  3. Trombetta CM, Kistner O, Montomoli E, Viviani S, Marchi S. Influenza viruses and vaccines: the role of vaccine effectiveness studies for evaluation of the benefits of influenza vaccines. Vaccines. 2022;10(5):714. doi:10.3390/vaccines10050714
  4. Centers for Disease Control and Prevention. Similarities and differences between flu and COVID-19. CDC website. Accessed June 12, 2025. https://www.cdc.gov/flu/about/flu-vs-covid19.html
  5. Baden, L.R. et al. Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine. N Engl J Med. 2021;384:403-416
  6. Centers for Disease Control and Prevention. Benefits of the flu vaccine. Flu Vaccines Work. January 14, 2025. Accessed July 1, 2025. https://www.cdc.gov/flu-vaccines-work/benefits/index.html
  7. Vaccine and Infectious Disease Organization. How are flu vaccine strains chosen each year? Accessed September 3, 2025. https://www.vido.org/news/2025/how-are-flu-vaccine-strains-chosen-each-year.php
  8. Centers for Disease Control and Prevention. CDC Seasonal Flu Vaccine Effectiveness Studies. Flu Vaccines Work. May 30, 2025. CDC website. Accessed May 30, 2025. https://www.cdc.gov/flu-vaccines-work/php/effectiveness-studies/index.html
  9. World Health Organization. About us. Global Influenza Programme. WHO website. Accessed May 21, 2025. https://www.who.int/teams/global-influenza-programme/about-us
  10. Huber VC, Thomas PG, McCullers JA. A multi-valent vaccine approach that elicits broad immunity within an influenza subtype. Vaccine. 2009;27(8):1192-1200. doi:10.1016/j.vaccine.2008.12.023
  11. World Health Organization. Tracking SARS-CoV-2 variants. WHO website. Accessed May 21, 2025. https://www.who.int/activities/tracking-SARS-CoV-2-variants
  12. World Health Organization. WHO Coronavirus Network (CoViNet). WHO website. Accessed June 16 2025. https://www.who.int/groups/who-coronavirus-network
  13. Tichy W. How Does a COVID mRNA vaccine really work?: an interview with Dr. Evelyn Tichy. Ubiquity. 2021;2021(July):1-12. doi:10.1145/3477388
  14. Press Release: Sanofi and Novavax announce co-exclusive licensing agreement to co-commercialize COVID-19 vaccine and develop novel flu-COVID-19 combination vaccines. Sanofi website. Accessed May 21, 2025. https://www.sanofi.com/en/media-room/press-releases/2024/2024-05-10-06-00-00-2879379
  15. Press Release: Two combination vaccine candidates for prevention of influenza and COVID-19 granted Fast Track designation in the US. Sanofi website. Accessed May 21, 2025. https://www.sanofi.com/en/media-room/press-releases/2024/2024-12-11-06-00-00-2995072
  16. NFID. What is an antiviral?. Accessed September 3, 2025. https://www.nfid.org/resource/what-is-an-antiviral/
  17. Qian Q, Fan G, Yang W, et al. Advances in diagnostic techniques for influenza virus infection: a comprehensive review. Trop Med Infect Dis. 2025;10(6):152. doi:10.3390/tropicalmed10060152
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