Getting a flu shot every year is one of the simplest and most important ways to protect your health. That’s especially true for older adults and those with lung conditions including asthma and chronic obstructive pulmonary disease (COPD), who are more vulnerable to dangerous complications such as pneumonia.
For people with these conditions, “the added risk on top of the potential consequences of pneumonia is that they already have compromised lungs,” said MeiLan Han, a professor of medicine and chief of the pulmonary and critical care division at University of Michigan Health.
Standard flu shots work, but research suggests older adults with lung disease may get additional protection from a high-dose vaccine. In September, researchers presented new findings from the FLUNITY-HD study, a large-scale analysis published last year in the Lancet journal, at the European Respiratory Society Congress. Among adults 65 and older overall, they found that high-dose flu shots reduced hospital admissions for flu or pneumonia by 8.8 percent compared with the standard-dose vaccine.
That might not sound like a major improvement, but people with chronic lung disease “are at particularly high risk of severe influenza and related complications,” said Lisa Steen Duus, a physician and research fellow at Herlev and Gentofte Hospital in Copenhagen who presented the findings. “Gaining just a little bit of extra protection for hospitalizations might be extra important for this group.”
Here’s what to know about high-dose flu vaccines, who should get one and how they may help protect people with chronic lung conditions.
What are high-dose flu vaccines?
Flu vaccines work by training your immune system to recognize the virus and develop antibodies against it. One of their main targets is hemagglutinin, a protein on the surface of the influenza virus that helps it infect cells. If you’re later exposed to a similar strain of flu, those antibodies can help protect you from infection or severe illness.
There are several types of flu vaccines. Most adults get a standard-dose shot such as Fluarix or Fluzone. But because people 65 and older are at higher risk of serious flu complications, the Centers for Disease Control and Prevention Advisory Committee on Immunization Practices (ACIP) recommends they get one of three enhanced vaccines when possible:
- The high-dose unadjuvanted inactivated influenza vaccine, Fluzone High-Dose — the type included in the FLUNITY-HD study, which compared how well high-dose and standard-dose flu vaccines protected older adults. It “contains more influenza antigen than a standard shot, and in theory produces a stronger immune response,” Han explained.
- The recombinant flu vaccine, Flublok, which is manufactured with a different technology and doesn’t use vaccine virus or chicken eggs.
- The adjuvanted flu vaccine, Fluad, which contains a standard dose but has an added ingredient to stimulate a stronger immune response.
ACIP recommended these vaccines for older people after a growing body of research suggested “that in most seasons, all three had about a 22 percent greater effectiveness in actually preventing influenza,” said William Schaffner, a professor of infectious diseases at Vanderbilt University Medical Center. Earlier this year, a meta-analysis of randomized trials with more than 600,000 participants found that among adults 65 and older, high-dose inactivated flu vaccines reduced the risk of hospitalization compared with standard-dose shots.
So if you’re 65 or older — even if you don’t have an underlying condition such as asthma — a high-dose flu vaccine or one of the other two enhanced options may offer additional protection. That can be particularly important for older adults, “who may not produce as robust an immune response as people do when they’re younger,” Han said.
How are high-dose vaccines beneficial for people with lung disease?
The flu can cause a range of symptoms, including fever, muscle aches, a runny nose or fatigue. But complications can quickly become serious. “It can cause both direct pneumonia from the virus itself and inflammation in the lungs, but it can also put people at risk for what’s called a secondary bacterial infection,” Han said. Regardless of a person’s health status, these complications can result in respiratory failure, hospitalization and death, she added.
In the United States, the flu causes an estimated 6,300 to 52,000 deaths each year, according to the CDC, and as many as 710,000 hospitalizations.
Having a chronic lung condition such as asthma, COPD or pulmonary fibrosis can raise those risks even further. “With any lung disease, you are going to be more prone to have complications to infections such as flu,” said Antonio Anzueto, a professor of medicine and section chief of pulmonary at South Texas Veterans Healthcare System.
People 65 and older with an underlying lung condition may already have impaired immune systems, Anzueto said. That makes it especially important for them to receive a higher-dose vaccine “to stimulate the immune response and build antibodies.”
For the latest analysis, Duus and her team looked at data from the FLUNITY-HD study, which combined two large-scale trials in Denmark and Spain over multiple flu seasons and was published in the Lancet last year. The study compared hospitalization outcomes among adults age 65 and up who received either the high-dose inactivated flu vaccine or a standard-dose shot. The high-dose vaccine was more effective at preventing hospitalizations for the flu or pneumonia, as well as cardiorespiratory hospitalizations.
About half of the participants in the FLUNITY-HD study had at least one chronic condition. From that group, the researchers identified participants with lung diseases including asthma, bronchiectasis, bronchitis, COPD, cystic fibrosis, emphysema, interstitial pulmonary disease, respiratory tuberculosis and sarcoidosis, as well as those who had received a lung transplant.
Participants with lung disease were more likely to require hospital care. Among this group, the high-dose flu vaccine significantly reduced flu and pneumonia hospitalizations compared with the standard-dose shot. The effects were “consistent in both participants with or without chronic lung diseases,” Duus said.
So if the high-dose flu vaccine offers superior protection, why doesn’t everyone get it? “Many of us have wondered whether those vaccines could also work for people who are 58 and have chronic lung disease or heart disease or some other chronic medical condition,” Schaffner said. But because enhanced vaccines have not yet been studied as extensively in younger people, there isn’t enough evidence to support a preferential ACIP recommendation for broader use in this population, he explained.
There is one exception: Adults ages 18 through 64 who have had a solid organ transplant and are taking immunosuppressive medications may receive a high-dose or adjuvanted flu vaccine.
How to protect yourself this flu season
The fall and winter respiratory-virus season is approaching, and the flu shot is the best way to protect yourself. Getting vaccinated can also help protect people around you who are at higher risk of developing complications from the flu, including young children, pregnant people and those with underlying health conditions.
It takes about two weeks for your body to develop antibodies, and protection wanes over time. The goal, Anzueto explained, is to time your vaccination so you’re protected through the winter peak of flu season. For this reason, the CDC recommends getting your flu shot between September and the end of October, but your doctor can let you know if there’s a preferred time based on how the virus tends to circulate in your area.
If you’re 65 or older, the CDC recommends one of the three enhanced vaccines when available. “The availability of various vaccines vary widely,” Han said. If your doctor’s office or local pharmacy doesn’t have the high-dose vaccine, you may have to call ahead to a few locations to find somewhere that does. The CDC does not recommend that adults over 65 get the nasal spray vaccine.
All available flu vaccines are safe and effective. But it’s important to have reasonable expectations about what the flu shot can and can’t do, Schaffner said. Even with a high-dose vaccine, you may still get the flu, but that doesn’t mean vaccination isn’t worth it.
Respiratory virus vaccines for flu, the coronavirus and RSV are most effective at preventing serious disease, Schaffner said. “Even though you’ve been vaccinated, you may still get a milder case of influenza, but the vaccine likely kept you out of the hospital,” he said.
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