If You're in a Hurry
Older adults, especially those 65 and older, have weaker immune systems and face much higher risks from the flu. Standard flu shots may not offer enough protection for them. High-dose and enhanced flu vaccines, designed specifically for older adults, provide stronger protection and have been proven to reduce severe complications, hospitalizations, and deaths. The CDC and health authorities in many countries recommend these enhanced vaccines for seniors. If you’re eligible, ask your healthcare provider about getting an improved flu shot for the best protection this season.
If you’re not in a hurry, the full blog post is below...
Introduction
Every fall, millions of people roll up their sleeves for their annual flu vaccine. For most adults, a standard dose works just fine. But if you’re over 65, your doctor might recommend something different: a high-dose flu vaccine. These vaccines are not a marketing ploy. They are a specially formulated vaccine designed to overcome a challenge that comes with aging, and understanding why it exists can help you make better decisions about your health.
When Our Immune System Slows Down
As we get older, our immune system doesn’t work quite as well as it used to. Scientists call this process , which is a fancy way of saying that our body’s defense system becomes less responsive over time. Think of it like a security alarm that takes longer to sound or doesn’t ring as loudly when there’s a threat.
This change happens to everyone as they age. Our bodies produce fewer fresh immune cells that can recognize and fight new infections. At the same time, we develop a low-level inflammation throughout our body, sometimes called . These two processes working together mean that when an older adult gets a standard flu vaccine, their body might not respond as strongly as a younger person’s would.
The consequences of this weakened response are serious. People 65 and older account for about 70% to 85% of all flu-related deaths in the United States each year. Even after surviving a flu infection, older adults are much more likely to end up in the hospital. In fact, someone over 85 is 32 times more likely to die from flu-related pneumonia than someone between 65 and 69. These aren’t just statistics. They represent parents, grandparents, and friends whose aging immune systems struggled to fight off what younger people might experience as a manageable illness.
Building a More Powerful Vaccine
The high-dose flu vaccine was created specifically to address this problem. Instead of containing the standard amount of antigen (the part of the vaccine that trains your immune system to recognize the flu virus), the high-dose version contains four times as much. The brand name you’ll most likely encounter is , which Sanofi Pasteur manufactures.
The antigen in flu vaccines is a protein called . This protein sits on the surface of the flu virus and helps it attach to cells in your respiratory system. When you receive a flu vaccine, your immune system learns to recognize this protein. If the real flu virus tries to infect you later, your body can quickly identify it and mount a defense.
In a standard flu vaccine, there are 15 micrograms of hemagglutinin for each flu strain. The high-dose vaccine bumps this up to 60 micrograms per strain, giving your immune system more material to work with. The idea is straightforward: if your aging immune system needs more help getting activated, provide more of the signal it needs to respond.
This approach works. A major clinical trial involving about 32,000 adults over age 65 found that the high-dose vaccine was at preventing laboratory-confirmed flu than the standard vaccine. More recently, a massive real-world study called involving nearly half a million older adults showed that the high-dose vaccine reduced hospitalizations from flu by an additional 31.9% compared to standard vaccines.
Who Should Get the High-Dose Vaccine
In the United States, the high-dose flu vaccine is approved for people 65 years and older. The (CDC) and its Advisory Committee on Immunization Practices (ACIP) specifically recommend that seniors receive either a high-dose vaccine, an adjuvanted vaccine (a different type of enhanced vaccine), or a recombinant vaccine rather than a standard flu shot.
The recommendation exists because the benefits are measurable. Research shows that high-dose vaccines help prevent not just flu infections but also the serious complications that land older adults in the hospital. These complications include pneumonia, heart and breathing problems, and even death. When you consider that older adults who are hospitalized with flu have a substantial risk of dying within 30 days, even after they’re discharged from the hospital, the value of better protection becomes clear.
Some people between 18 and 64 years old might also receive the high-dose vaccine, specifically those who have had solid organ transplants and take medications that suppress their immune system. These individuals face similar challenges to older adults because their medications intentionally weaken their immune response to prevent organ rejection.
What to Expect from the High-Dose Vaccine
The high-dose flu vaccine is given as a single injection in your upper arm muscle, just like the standard flu shot. Because it contains more antigen, you might experience slightly more noticeable side effects compared to a standard vaccine. These reactions are usually mild and temporary, typically lasting just a few days.
The most common side effects include where you received the shot. You might also experience muscle aches, tiredness, or a headache. In clinical studies comparing the two vaccines, about 36% of people who got the high-dose vaccine reported pain at the injection site, compared to 24% of those who received the standard vaccine. Similarly, muscle aches occurred in about 21% of high-dose recipients versus 18% of standard-dose recipients.
These differences might sound concerning, but it’s worth putting them in perspective. First, most side effects resolve within three days. Second, these reactions are signs that your immune system is responding to the vaccine. They’re not dangerous. Third, the slight increase in temporary discomfort is a reasonable trade-off for significantly better protection against a disease that kills tens of thousands of older Americans every year.
How Other Countries Protect Their Older Adults
The high-dose flu vaccine isn’t just an American innovation. It’s used in many countries around the world, though it goes by different names depending on where you are. In Europe, the same high-dose vaccine is marketed under the brand name and is approved for adults 60 years and older. The vaccine has been approved and is available in countries including the United Kingdom, Canada, Australia, Germany, and Italy.
Several European countries now specifically recommend enhanced vaccines (either high-dose or adjuvanted) for their older populations. Austria, Germany, Greece, Italy, the Netherlands, the Republic of Ireland, and the UK all recommend both adjuvanted and high-dose vaccines for protecting older adults against flu. Germany’s Standing Committee on Vaccination at the Robert Koch Institute initially recommended only the high-dose vaccine but updated its guidance in 2024 to recognize that both high-dose and adjuvanted vaccines offer comparable protection.
Canada also approves the high-dose vaccine for adults 65 and older. Their National Advisory Committee on Immunization provides guidance on flu vaccination, and about 74% of Canadian adults over 65 received a flu vaccine during the 2022-2023 season. In Australia, the high-dose vaccine is available for people 60 and older and has been approved by the Therapeutic Goods Administration. Australian health authorities recommend that adults over 65 receive either an adjuvanted vaccine (which is funded through their National Immunisation Program) or a high-dose vaccine in preference to standard flu shots.
What About Countries That Don’t Use High-Dose Vaccines
Not every country uses the high-dose flu vaccine, but that doesn’t mean older adults in those places go unprotected. Many countries use adjuvanted flu vaccines instead, which work differently but achieve a similar goal of boosting immune response in older people.
An adjuvant is a substance added to a vaccine to enhance the body’s immune response. The most widely used adjuvant in flu vaccines is called , which is an emulsion containing squalene oil (a naturally occurring substance found in humans, animals, and plants). The adjuvanted flu vaccine marketed as has been used in Italy since 1997 and is currently approved in 38 countries. More than 160 million doses of MF59-adjuvanted flu vaccines have been administered globally.
The adjuvanted vaccine contains the same amount of antigen as a standard flu shot but includes the adjuvant to help stimulate a stronger immune response. Multiple real-world studies have shown that adjuvanted vaccines offer better protection for older adults compared to standard vaccines. In fact, recent research from Kaiser Permanente found that among people 65 and older during the 2022-2023 flu season, adjuvanted flu vaccines were 62% more effective than standard vaccines at preventing hospitalizations for flu.
Many European countries that prioritize vaccination for their elderly populations recommend adjuvanted vaccines. In Denmark, France, Germany, Ireland, Italy, Spain, and Sweden, adjuvanted trivalent (three-strain) influenza vaccines are available and recommended for people 65 and older. The United Kingdom has recommended adjuvanted flu vaccines for older adults since the 2018-2019 flu season.
Some countries use a mix of approaches. For instance, in regions where high-dose vaccines aren’t available or affordable, standard flu vaccines are still provided to older adults because some protection is always better than none. The World Health Organization and the European Centre for Disease Prevention and Control recommend that all adults 65 and older receive an annual flu vaccination, even in places where enhanced vaccines aren’t accessible.
The Bottom Line on Flu Protection for Older Adults
The high-dose flu vaccine represents an evidence-based response to a biological reality: aging changes how our immune system works, and standard vaccines don’t always provide adequate protection for older people. By quadrupling the amount of antigen, the high-dose vaccine helps overcome age-related immune decline and provides substantially better protection against flu and its complications.
If you’re 65 or older, talk with your healthcare provider about which flu vaccine is right for you. The CDC recommends enhanced vaccines (high-dose, adjuvanted, or recombinant) over standard vaccines for older adults. If an enhanced vaccine isn’t available when you’re ready to get vaccinated, getting a standard flu vaccine is still worthwhile, but it’s worth asking when an enhanced option might become available.
The research backing these recommendations is substantial and continues to grow. The recent included nearly half a million participants and demonstrated clear benefits for hospitalization prevention. Dozens of other studies conducted over more than a decade have consistently shown that enhanced vaccines work better for older adults.
Getting vaccinated protects not just you but also the people around you. When you’re less likely to get sick, you’re less likely to spread flu to others, including people who might be even more vulnerable than you are. And by reducing your risk of serious complications and hospitalization, you’re helping to ease the burden on healthcare systems during flu season.
The high-dose flu vaccine won’t eliminate all risk. No vaccine is perfect, and even with enhanced protection, some people will still get the flu. But the goal isn’t perfection. It’s better odds. It’s reducing your chances of ending up in the hospital or experiencing life-threatening complications for older adults facing an immune system that doesn’t respond as vigorously as it once did; that extra protection can make all the difference.