Vaccine Adjuvants

Efforts to develop safe and effective vaccines increasingly involve the use of adjuvants—substances formulated as part of a vaccine to boost immune responses and enhance the vaccine’s effectiveness. NIAID supports a broad portfolio of vaccine adjuvant research, ranging from basic immunology studies to clinical testing of adjuvanted vaccine candidates. 

Vaccine adjuvants accelerate, enhance and prolong the immune responses triggered by antigens—the vaccine components that elicit pathogen-specific immune responses. Certain populations, such as people with compromised immune systems, the elderly and the very young, particularly benefit from vaccines with adjuvants because their immune systems may require an extra boost to provide protection. Adjuvants also can allow vaccine developers to use less antigen, which in some cases may be in short supply or costly. Additionally, adjuvanted vaccines can elicit more durable immune responses, reducing or eliminating the need for booster vaccinations.

Aluminum-containing adjuvants, collectively termed alum, have been safely used in vaccines since the 1930s and are still widely used today. Aluminum is among the most common metals found in nature and is present in food and water. Scientific research has shown that the trace amounts of aluminum in vaccines are safe and not readily absorbed by the body.

For many years, alum was the only adjuvant added to vaccines in the United States. In recent decades, however, technologic and scientific advances have increased understanding of human immunity, and these insights have led to the identification of new adjuvants and many promising adjuvant candidates. In 2009, FDA approved Cervarix, a human papillomavirus vaccine containing a novel adjuvant called AS04. Since then, several additional vaccines containing novel adjuvants have been approved for use in the United States. See CDC’s Adjuvants Help Vaccines Work Better web page for a complete list.

Learning more about how adjuvants work to stimulate specific immune responses is critical to the development of new and improved vaccines. Adjuvant research lays a foundation for vaccine developers to improve the protection that current vaccines offer; design vaccines for emerging infectious diseases; expedite efforts to develop vaccines to protect against diseases without preventive inoculations like HIV and tuberculosis; and develop vaccines to treat allergies, autoimmune diseases and cancer.

The ultimate goal of NIAID’s adjuvant research programs is to develop a “toolbox” of adjuvants that can be matched with antigens to optimize vaccine efficacy. NIAID also aims to strengthen immunology research to further increase understanding of immune mechanisms and fuel the adjuvant pipeline. Other research projects focus on shedding light on how adjuvants can work in combination to enhance immune responses. NIAID developed its first strategic plan for adjuvant research in 2011. Due to advances in adjuvant science, many of which were driven by NIAID-supported programs, NIAID in 2018 updated its adjuvant research agenda, culminating in the 2018 Strategic Plan for Research on Vaccine Adjuvants.

Learn more about NIAID-funded vaccine adjuvant research programs.

Additional Resources

For more information about adjuvants and other vaccine ingredients, see FDA’s Q&A about Common Ingredients in U.S. Licensed Vaccines. For a general overview of adjuvants and a list of adjuvants included in vaccines licensed in the United States, see CDC’s Adjuvants Help Vaccines Work Better web page.

Content last reviewed on July 2, 2019