Vaccine Basics: Why Do Adjuvants Matter?

( Newport Laboratories )

When it comes to understanding vaccines, it’s important to recognize the differences between the two basic ingredients in a killed vaccine: antigens and adjuvants.

Although antigens are well understood, there’s far less understanding of the vital role adjuvants play in a vaccine. According to the Centers for Disease Control and Prevention, adjuvants simply help vaccines work better. Adjuvants are ingredients used in some vaccines that help create a stronger immune response.

“Adjuvants are the biggest variable that impact vaccine performance,” says Keith Wilson, DVM, senior professional service veterinarian at Boehringer Ingelheim. “Nearly everything else within a killed vaccine is fixed, such as the antigens and routes of administration.”

Adjuvants vary, so it’s important to be able to identify the adjuvant that has the right properties needed to solve your herd’s health challenges. 

Antigens in killed vaccines are viruses or bacteria that have been inactivated so they don’t cause disease. However, even in an inactivated state, antigens set off an alarm within the immune system, signaling that a foreign invader is present. The adjuvant responds by amplifying that alarm, allowing the immune system to build up its defenses so it’s better prepared to fight off the real thing.

Some adjuvants kickstart an earlier onset of immunity or a longer duration of immunity. Wilson says others can help create a stronger immune response or even a specific type of immune response.

Antigens and adjuvants react differently to one another. Wilson says an antigen needs to be compatible with an adjuvant to enable optimum vaccine efficacy and stability, especially in custom-made vaccines where there is often more than one antigen.

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