Less B Cell Adaptation Could Cut Influenza Vaccine Efficacy in Older Adults

Influenza vaccines may be less effective in the elderly due to a lack of antibody diversity, according to a new study. However, the findings also suggest a path forward to create even more effective flu vaccines.

The vast majority of influenza-related deaths occur in patients over the age of 65, making it a leading cause of death for the elderly. It is believed that this is due to changes in the immune systems of older patients, but a cross-country team of investigators wanted to find out exactly what was leading to the phenomenon.

The investigators decided to look more closely at B cells, the cells responsible for producing antibodies, to see how they acted differently in young patients and old patients.

Writing in the journal Cell Host & Microbe, Carole Henry, PhD, of the University of Chicago, and colleagues report that the B cells secreted by elderly patients acquire fewer mutations, rendering them less adept at combating the rapidly changing influenza virus.

While the B cells of young patients mutated in such a way as to be able to tackle new evolutions in the flu virus, Henry and colleagues found that elderly patients’ B cells were essentially stagnant.

“We were surprised to see how striking the difference was between adaptability of the antibody response from elderly individuals compared to young adults,” Henry told Contagion®'s sister publication MD Magazine®. These older patients’ B cells were less potent and less able to fight off the influenza virus, the study found.

"The major implication is that when a newly circulating influenza virus infects elderly individuals, they don't have quite the right tool to fight it because their antibodies are not as protective," says senior study author Patrick Wilson, PhD, also of the University of Chicago, in a press release.

The research also showed that the B cells of older patients were better able to fight off older strains of influenza—the strains of flu that would have been pervasive when the elderly patients were younger. Conversely, the B cells of elderly patients were less effective against newer mutations of the virus, a deficit not seen in younger patients.

The good news, Henry said, is that improvements to the flu vaccine could help solve the problem.

“More recent vaccines developed especially for the elderly population (high dose, adjuvanted) are now on the market,” Henry said. “The next step will be to evaluate antibody adaptability (if we can drive mutations) in elderly individuals immunized with these vaccines. Understanding the underlying biological basis of the observation that we see in the elderly population will be particularly important.”

Henry added that while the research offers insights into the reasons why the flu vaccine may not work as well for older patients, the findings in no way mean that older patients should not get the vaccine.

“To this day, vaccination is the best way to protect elderly individuals from influenza virus infection and we are NOT saying that people shouldn’t be vaccinated or that the current vaccines are useless for elderly individuals,” she said.

The article, "Less B Cell Adaptation Reduces Flu Vaccine Efficacy in Older Adults," originally appeared on MDMag.com.