Influenza, or flu, is a contagious respiratory infection caused by several flu viruses that infect the nose, throat and lungs. People infected with the seasonal flu virus feel miserable with fever, chills, muscle aches, coughing, congestion, headache and fatigue for a week or so. Most people who get the flu get better within two weeks, but some people may develop serious complications, such as pneumonia. Pandemic influenza is when a new flu virus strain occurs that can spread easily from person-to-person and the virus is one for which most people have no immunity.

Why Is the Study of Influenza a Priority for NIAID?

Each year, seasonal influenza sickens millions and causes thousands of hospitalizations and flu-related deaths. Even healthy people can get very sick from the flu and spread it to others. Flu infection can present particularly serious problems for young children, the elderly, pregnant women and people with certain medical conditions, such as asthma and heart disease. In addition to seasonal influenza, NIAID is also working to prepare for a potential pandemic flu threat. Pandemic flu occurs when a new flu virus strain emerges for which humans have little to no immunity, which enables the virus to spread easily from person-to-person. Flu viruses of this type can sicken millions around the globe.

How Is NIAID Addressing This Critical Topic?

NIAID is conducting and supporting research to find new and improved ways to diagnose, treat and prevent influenza infection. This includes working toward a universal flu vaccine that could provide long-lasting protection against multiple strains of influenza, such as those that cause seasonal flu as well as emerging forms capable of causing a global pandemic.

To learn about risk factors for the flu and current prevention and treatment strategies visit the MedlinePlus flu site.

Credit: NIAID

A colorized electron micrograph of the structure for a universal flu vaccine. The nanoparticle is a hybrid of a protein scaffold (blue) and eight influenza hemagglutinin proteins on the surface (yellow). The hemagglutinin was specifically engineered to display antibody binding sites common to all human influenza subtypes.

Basic Research

NIAID has a longstanding commitment to conducting and supporting the basic research necessary to understand how influenza strains emerge, evolve, infect and cause disease (called pathogenesis) in animals and humans. Results from this research are used to inform the design of new and improved influenza vaccines, diagnostics and antiviral drugs to treat flu infection.


Developing new and improved influenza vaccines as well as a universal flu vaccine are high priorities for NIAID. Specifically, NIAID conducts and supports research to find innovative technologies to improve vaccine production flexibility; new more broadly protective flu vaccines; create vaccines that are effective against newly emerging influenza viruses; develop adjuvants to boost vaccine results; and create a universal flu vaccine effective against multiple influenza strains.


NIAID conducts and supports research to find faster, more accurate, cost-effective, and portable ways to diagnose the flu. Rapid diagnostics that enable medical professionals to quickly determine if a patient has the flu – and if so, which strain – can ensure that the patient receives the most appropriate care. 


Time is of the essence when treating influenza. Several antiviral drugs are approved for flu treatment, but they are most effective when taken within the first two days after flu symptoms appear. NIAID conducts and supports research to develop a new generation of antiviral drugs to treat the flu and the severe illness that can result from it. 

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Clinical Trials

NIAID conducts and supports clinical research to find new influenza vaccines, treatments and diagnostics through its Division of Intramural Research, the Division of Clinical Research, its Vaccine Research Center and through its Vaccine Treatment and Evaluation Units

Networks & Collaborations

NIAID encourages partnerships among other agencies and foundations, private industry, federal and local government and other organizations with similar goals to help build and sustain research infrastructure and to translate and implement research findings as public health practices.

Content last reviewed on May 12, 2016