K-State research suggests obesity reduces influenza vaccine effectiveness in male animals

Newly published research at Kansas State University has observed a notable difference in influenza vaccine responses between male and female mice with obesity. While the research has not yet been evaluated in humans, early results in animals suggest that males with obesity derive less protective benefit from the influenza vaccine than females with obesity.

"Obesity is increasing globally and is known to reduce the effectiveness of influenza and other vaccines," said Santosh Dhakal, assistant professor of infectious diseases in the College of Veterinary Medicine. "However, little is known about whether this reduction affects males and females in the same way."

Using a research model of obese and non-obese control animals, Dhakal's team investigated sex differences in influenza vaccine-induced immunity and protection. Males and females, with or without obesity, received two doses of an inactivated influenza vaccine at three weeks apart.

The results showed that females, whether they had obesity or not, generated higher levels of protective antibodies and experienced milder disease following virus challenge.

Dhakal said vaccinated males with obesity produced the weakest antibody responses. When exposed to the virus, they developed more severe disease and were unable to clear the virus from the lungs effectively.

"Our findings highlight an important gap in understanding how obesity and biological sex interact to shape vaccine effectiveness," Dhakal said. "These findings could inform future influenza vaccine design and testing, particularly for the globally rising populations with obesity."

The study, "Females with obesity exhibit greater influenza vaccine-induced immunity and protection than males in a mouse model," was published in the Dec. 17 issue of Frontiers in Immunology.

"Although the vaccine was not as protective in males as in females, it is important to emphasize that flu vaccination still provided benefits for males with obesity compared to remaining unvaccinated," Dhakal said.

Dhakal's lab team and co-authors, all from K-State's Department of Diagnostic Medicine and Pathobiology, include Brian Wolfe, Saurav Pantha, doctoral candidate in pathobiology; Saranya Vijayakumar, research assistant; Shristy Budha Magar, master's student in veterinary biomedical science; and Tawfik Aboellai, clinical professor and anatomic pathologist for the Kansas State Veterinary Diagnostic Laboratory.