In the United States, the annual influenza vaccine is recommended for everyone age six months and older. Since older adults bear a disproportionate burden of influenza (flu), it is vitally important that every older adult in a nursing, assisted living, or any other type of long term or post-acute care center is vaccinated annually. It is also important that everyone who works in these environments be vaccinated annually to further reduce the spread of influenza.
The good news is that more health care workers in long term care facilities are getting their influenza vaccine than ever before (70 percent last season). For the benefit of patients and health care workers, these rates should continue to be pushed even higher.

Flu Outcomes In Older Adults

Adults aged 65 years and older are six times more likely to die from the flu and its related complications than all other age groups combined.

What are the risks?The 65-plus age group also makes up the largest portion of flu-related hospitalizations. In a recent severe season (2014-2015), nearly four in every five hospitalizations (more than 750,000) were among individuals aged 65 years and older.

These outcomes are only part of the story. Less well known, but extremely important, is the fact that in adults aged 65 years and older, influenza increases the risk of heart attack by three to five times and the risk of stroke by two to three times in the first two weeks of the infection. The risk of heart attack and stroke remains elevated by about one-third for up to three months after influenza infection. This long-term effect means that well after flu symptoms have subsided, the infection may still cause harm.

A study that included nearly 250,000 U.S. nursing center residents showed a strong connection between the severity of influenza circulating in the community and a decrease in the residents’ abilities to perform activities of daily living. The level of decline measured in the study can be reversed in fewer than 10 percent of long term care residents, suggesting that the debilitating impact of influenza in this population is permanent.

Flu Symptoms In Older Adults

Older adults infected with influenza can have somewhat different symptoms than what many think of as traditional flu. The sudden onset of fever typical in children and younger adults may be replaced by malaise in older adults, who cannot mount the same strong immune response that triggers the fever.

In addition, older adults sometimes have gastrointestinal symptoms, including pain, diarrhea, nausea, and vomiting along with the more common symptoms—aches, chills, runny nose, and nasal congestion.

This all can add up to a challenging diagnosis in older adults and a situation where they can remain undiagnosed but still able to spread the infection easily to others in the long term care setting.

The Aging Immune System Impact

The aging of the immune system leaves the body less prepared to fight infections, which is why influenza is often harder on older adults. Unfortunately, this is also why older adults have a less robust response to vaccines.

Annual vaccinationIn the United States, high-dose and adjuvanted vaccines are now available exclusively for use in the 65-plus population. The vaccines were designed specifically to provide a more robust immune response in older adults.

More than 50 million high-dose vaccines have been distributed in this country since its introduction in 2009. The vaccine has been shown to be more effective than the standard-dose vaccine for adults 65 years and older. In several post-licensure studies, compared with older adults who receive the standard-dose vaccine, those who received high-dose vaccine had a 24 percent lower risk of laboratory-confirmed influenza, a 7 percent reduction in all-cause hospitalizations, an 18 percent reduction in cardiorespiratory events, and a 40 percent reduction in pneumonia.

The adjuvanted influenza vaccine, which includes an ingredient that helps create a stronger immune response, was recently approved in the United States, and has been used for many years in other countries, including Canada and many across Europe, including Italy, where it was first approved 19 years ago.

More than 60 million doses have been distributed worldwide for use in older adults. There has not been a large-scale effectiveness trial for this vaccine, but in case studies it has been shown to be more effective specifically for older adults living in long term care settings.

Both of these vaccines cause more injection site reactions compared with standard-dose vaccines, but they are otherwise very well tolerated and safe. Older adults may receive either the high-dose or adjuvanted vaccine if available but should not forego vaccination in any case.

In fact, the Centers for Disease Control and Prevention strongly recommends using any influenza vaccine that is available versus waiting for one to become available. In other words, a vaccine deferred is often a vaccine not received, which leaves vulnerable patients with no protection at all.
William Schaffner, MD
William Schaffner, MD, is medical director at the National Foundation for Infectious Diseases. He is also professor of preventive medicine in the Department of Health Policy and professor of medicine in the Division of Infectious Diseases at Vanderbilt University School of Medicine in Nashville, Tenn. Additionally, he serves as an epidemiologist at Vanderbilt University Hospital. He can be reached at or (615) 322-2037.