CDC Recommends Stronger Flu Vaccine for Seniors

Pam Harrison

July 11, 2022

For years, the Centers for Disease Control and Prevention (CDC) has stressed the importance of seasonal flu shots for adults aged 65 and older. Now, the CDC recommends certain stronger flu vaccines for seniors, the CDC reports.

The CDC director has approved a new guideline that indicates that adults aged 65 and older should preferentially receive one of the higher-dose or adjuvanted influenza vaccines over standard-dose or unadjuvanted flu vaccines. The recommendation was made June 22 by majority vote of the Advisory Committee on Immunization Practices (ACIP) and will become official once published in the Morbidity and Mortality Weekly Report (MMWR), according to the the CDC.

The CDC specifically indicated three stronger flu vaccines for older adults: Fluzone High-Dose Quadrivalent (Sanofi Pasteur), Fluad Quadrivalent (Seqirus), and Flublok quadrivalent (Sanofi Pasteur). "In recent years, CDC has not recommended any one flu vaccine over another for any age group, and there is still no preferential recommendation for people younger than 65," the ACIP reports.

Dr Gregg Sylvester

"It boils down to immunosenescence, so if you look at where the most vulnerable population is for complications from influenza, it probably starts around the age of 50, but by the age of 65, the risk starts to go up quite a bit," Gregg Sylvester, MD, chief health officer, Seqirus, told Medscape Medical News. "And we know that people 70 and older really do have more severe complications from influenza."

He added, "One of the things we can do to an influenza vaccine is we can adjuvant it and rev up the immune system to make the appropriate antibodies, and that puts us in a much better place against influenza infection. So Fluad is designed to enhance our immune system and better protect us against the flu."

Real-World Studies

No direct, head-to-head studies have compared the three types of stronger flu vaccine with each other, according to a slide presentation prepared for the CDC meeting by Lisa Grohskopf, MD, MPH, team lead for the CDC Vaccine Policy Unit.

But observational (real-world) studies have compared aduvanted and higher-dose vaccines to standard-dose egg vaccines in seniors. For example, in a systematic review and meta-analysis that evaluated the effectiveness of the MF-59 adjuvanted trivalent (aTIV) or quadrivalent influenza vaccine in adults aged 65 years and older (, an analysis of 21 studies that compared the effectiveness of the aTIV to either no vaccination or standard-dose or high-dose, egg-based influenza vaccines showed that aTIV reduced outpatient office visits by 41% (95% CI, 21.9% – 54.9%) and that it reduced hospitalization by 58.5% (95% CI, 40.7% – 70.9%) relative to nonadjuvanted standard doses and that it was comparable to high-dose TIV. The authors received funding from Seqirus.

"The world's influenza experts say that if you've seen one influenza season, you've seen one influenza season, so the range of protection for vaccines is hard to predict each year," Sylvester noted.

"But the CDC does track protection rates [with standard vaccines], and they can be in the 40% range, [which is why] the CDC came out and said that we should preferentially give Fluad or the high-dose vaccine over standard egg vaccines for those 65 years of age and older," he reaffirmed.

According to the CDC, about 80% of influenza-related deaths and between 50% to 70% of influenza-related hospitalizations occur among adults 65 years of age and older. A cost-effectiveness analysis presented at the June 22 ACIP meeting found wide variation, depending upon the individual vaccine effectiveness and flu season severity, but enhanced vaccines for those older than 65 represent "a reasonable and efficient allocation of resources," the CDC ACIP influenza workgroup concluded.

More Effective Vaccines

Asked by Medscape Medical News to comment on the recommendation, Brenda Coleman, PhD, assistant professor of public health, Dalla Lana School of Public Health, Toronto, Ontario, Canada, reaffirmed that standard-dose egg vaccines are not nearly as effective for people 65 years and older as they are for younger patients.

"So we need to protect these people by being vaccinated ourselves but also by providing them with vaccines that are more effective [than standard-dose vaccines], and this adjuvanted vaccine as well as the high-dose vaccine are both much more effective in that age group," she said.

Coleman also noted that people don't often talk about the long-term sequelae that can occur following acute influenza infection, but Parkinson's-like syndrome and chronic fatigue do occur, and they can be as burdensome as long-COVID can be. "So we want to prevent these patients from getting sick, ending up in the hospital, and dying," she emphasized.

Sylvester is an employee of Seqirus. Coleman has disclosed no relevant financial relationships.

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