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Flu Vaccine Usage in Older Adults

April 13, 2017

Laura Haynes, PhD, a professor of immunology at UConn Health in Farmington, Conn., has conducted research funded by the National Institute on Aging that explored how advanced age impacts the immunity duration of the influenza vaccine.

Her current research compares the effectiveness of the traditional inactivated influenza vaccine with the high-dose vaccine in young and old patients with the ultimate goal of preventing influenza infection in the elderly, who are at higher risk of flu-related hospitalization or other serious health complications. Dr. Haynes recently shared why it’s important to administer effective and timely flu vaccines to older patients, who she said account for 90% of flu-related deaths and half of flu-related hospitalizations.

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What’s the main challenge of vaccinating the elderly against the flu?

It’s not about getting the flu shot to the elderly, because out of all the patient populations, they’re the most amenable to being vaccinated. The biggest challenge is using a vaccine that works well and ensuring it’s administered at the right time, because the duration of protection must last throughout the entire flu season for this high-risk population. That’s why older individuals shouldn’t receive the vaccine in August, when community pharmacies begin to promote the availability of flu shots. Ideally, they should wait until late October to be vaccinated, so the protection extends through March. The timing of the vaccine isn’t as big a deal for younger people, whose immune systems provide longer-lasting protection against the flu.

Why doesn’t the immune system in the elderly offer that same duration of protection?

We don’t have all the answers to that yet. The T cells that respond to the influenza vaccine offer short-lived protection with advanced age, and why that happens is the focus of our current research. We administered flu vaccines to young and old volunteers during the last fall season and collected blood samples from them throughout the fall and winter. We now have a kinetic examination for each participant before and after vaccination, so we can examine how CD8 and CD4 T cells react and determine how those reactions differ in younger and older individuals. Ultimately, we can interrogate changes in T cell expression and induction of protective immunity during the months after vaccination in both patient groups.

Will the research allow you to improve influenza vaccination in older adults?

The goal is to understand the different impact the vaccine has on the young and the aged, and to use that information to develop a more intelligently designed vaccine for older people. There are currently two vaccines geared toward the elderly population: a high-dose vaccine, which has proven to work well, and a new adjuvant vaccine, which is the normal dose vaccine with an adjuvant that’s designed to make it more immunogenic. Both the high-dose and the adjuvant vaccines induce more inflammation in patients. That means they’ll hurt more and may feel under the weather after administration. Patients with underlying inflammatory conditions might not be good candidates for either vaccine. That’s a decision providers need to make based on the health conditions of individual patients.

Is the additional cost of the more potent vaccines justified?

If the vaccines are more effective than the standard vaccine in keeping elderly patients healthier, that in and of itself results in significant healthcare savings and justifies the increased cost. We’re also examining how influenza leads to physical disabilities in the elderly, who suffer more muscle loss when they get the flu than younger infected individuals. They might need a walker or cane to move around, and lose their ability to live independently. Keeping the elderly healthy and in their own homes is a huge societal cost savings.

What other strategies improve vaccine effectiveness in the elderly?

Pre-treating individuals with vancomycin can improve the effectiveness of a vaccine, although I’m not sure how mainstream that practice is. More research is needed to determine what vancomycin does at the cellular level and along chemical pathways to determine if its effect can be mimicked with other agents. We do know that vancomycin reduces inflammation. In general, inflammation is lowered by managing metabolic disorders such as diabetes and pre-diabetes, keeping blood sugar and metabolism under control, and lowering body mass through lifestyle interventions. Vaccines work better in healthy individuals, so efforts to improve the effectiveness of the influenza vaccine must be part of larger, multifaceted patient care model.

Dan Cook

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