adjuvantes

Adjuvantes, in the context of immunology and vaccinology, are substances added to vaccines to boost the immune response to an antigen. They help increase the magnitude and duration of immunity, can reduce the amount of antigen required, and may broaden protection across different populations and variants.

Mechanisms: Adjuvants act by creating an inflammatory milieu at the injection site, recruiting and activating antigen-presenting cells, and enhancing antigen uptake and presentation. Many adjuvants stimulate innate immune receptors such as Toll-like receptors, NOD-like receptors, or promote cytokine production. Others function as delivery systems that improve antigen delivery to lymph nodes or protect the antigen from degradation.

Examples: Aluminum salts (alum) are the oldest and still widely used adjuvants. Modern adjuvant systems include oil-in-water emulsions such as MF59 and AS03, liposomal formulations, and saponin-based matrices like Matrix-M. They also include Toll-like receptor agonists such as MPL (monophosphoryl lipid A) and CpG oligodeoxynucleotides, and combination systems like AS04 (alum with MPL).

Safety and regulation: Adjuvants undergo safety assessment in preclinical and clinical trials and are subject to regulatory approval before use in vaccines. Common local reactions include pain, redness, and swelling; systemic reactions such as fever may occur but are generally uncommon. Rare inflammatory or autoimmune events are monitored through post-marketing surveillance.

Other use of the term adjuvant: In medicine, adjuvant therapy refers to additional treatment given after the primary therapy to reduce recurrence or improve survival, notably adjuvant chemotherapy, radiotherapy, or hormonal therapy in cancer. The term underscores the aim of enhancing outcomes beyond the primary intervention.