Influenza Vaccines

NIAID supports and conducts research to develop vaccines against newly emerging influenza (flu) viruses, improve seasonal flu vaccines, and create a universal flu vaccine that would protect people against multiple flu strains, including potential pandemic strains, over multiple flu seasons. The program also aims to make flu vaccine production and administration more efficient, while improving the body’s immune response to vaccination.

Seasonal Influenza Vaccine

As influenza circulates around the world each year, the virus’ genes mutate, which causes proteins on the surface of the virus to structurally change. Although these changes are usually small, over time, they accumulate to cause “antigenic drift,” which enables the flu virus to partly evade the protections people have built up either through previous flu vaccinations or exposure to flu viruses. Antigenic drift in human flu viruses is what causes the changes in seasonal flu viruses each year and is why the seasonal flu vaccine must be updated annually. The U.S. Centers for Disease Control and Prevention recommends a yearly flu vaccine for everyone six months and older.

Scientists monitor the changes in globally circulating flu strains and use the information to predict which strains are likely to be the most prevalent during the next flu season. The seasonal flu vaccine is then designed to protect against three or four predicted dominant strains. Sometimes, however, the strains selected for the seasonal flu vaccine are a poor match to the circulating strains. Scientists must select vaccine strains months in advance of the upcoming flu season due to the time-consuming production process, and sometimes an existing but unexpected flu strain will become prevalent during the flu season. This occurred during the 2014-2015 flu season; the flu vaccine that season was less than 20 percent effective in protecting against influenza infection. NIAID is supporting research efforts to improve seasonal flu vaccine strain selection and vaccine effectiveness.

Influenza Surveillance and Risk Assessment

NIAID supports and conducts research to further our basic understanding of how flu strains emerge, evolve, infect and cause disease in animals and humans. Read more about influenza surveillance and risk assessment.

Influenza Vaccine Production and Design

NIAID is pursuing technologies and vaccine platforms that could increase the efficiency of vaccine production and manufacturing. Read more about influenza vaccine production and design.

Universal Influenza Vaccine Research

A key focus of NIAID’s influenza research program is developing a universal flu vaccine---one that could protect against multiple flu subtypes and eliminate the need for an annual seasonal flu vaccine. Read more about universal flu vaccine research.

Pandemic Influenza Vaccine Research

Influenza pandemics occur when a new flu strain emerges to which people have little to no immunity and infection is transmitted easily from person-to-person. Read more about pandemic influenza research.

Content last reviewed on June 8, 2017