Even if we’re otherwise healthy, our immune systems naturally become less efficient at fighting off infection as we age. That’s why older adults face a higher risk of severe illness from viruses like influenza and COVID.

mRNA vaccines, like the ones for COVID, and the just-approved mRNA flu vaccine (mFLUSIVA), are vaccines that give your cells temporary instructions to make a harmless protein from a virus. Your immune system recognizes the protein as foreign and builds an immune response against it.

Explore how these vaccines work, and their distinct advantages over conventional vaccines, so you can make informed decisions about your health.

What are mRNA vaccines?

Messenger RNA (mRNA) vaccines are a type of vaccine that instructs cells in the body to produce a harmless piece of a virus—like the spike protein found on the surface of the COVID-19 virus (SARS-CoV-2).This small piece of the virus triggers our immune system to recognize it and produce antibodies in response. If we’re later exposed to the actual virus while out shopping or at a social gathering, our immune system is already primed to fight it off and protect us from serious illness.

Unlike traditional vaccines, which typically use a weakened or inactive form of the virus, mRNA vaccines use a small piece of genetic code to achieve the same result. This technology allows for faster development and a more targeted immune response, making it especially valuable in preventing serious illness from viruses like the flu and COVID. 

It's important to know that mRNA technology is not new; it has a long history behind it. According to the Centers for Disease Control and Prevention (CDC), scientists have been researching and working with mRNA vaccines for decades.

What are the advantages of mRNA-based vaccines?

Why are mRNA vaccines so important for older people? Common infectious diseases can lead to severe illness, hospitalization, or even death in this population. For example:

• Older adults continue to be at highest risk for getting very ill from COVID. Between July 2024 and June 2025, COVID deaths were highest among adults age 65 and older (4,009 deaths), with rates jumping significantly among those 75 and older (16,375 deaths).¹ In addition, the risk of severe illness from COVID grows along with the number of chronic conditions a person has—such as obesity, diabetes, or sickle cell disease.²
• The seasonal flu, which typically causes mild illness in younger people, poses a real danger to older people. Adults age 65+ are at much greater risk for developing serious complications from the flu compared with their younger, healthier counterparts.³ Seasonal flu-related hospitalizations and outpatient visits reached a 15-year high during the 2024-25 respiratory virus season.⁴ According to CDC, there were more than 710,000 flu-related hospitalizations and 45,000+ deaths.5

Although mRNA and traditional vaccine can't prevent you from catching COVID, they do provide a powerful line of defense that can significantly reduce the risk of negative health outcomes.

Five key advantages of mRNA vaccine technology

1. High efficacy in preventing infection and severe illness. In a large phase 3 clinical trial, Moderna's new mRNA flu vaccine was found to be 26.6% more effective than a licensed standard-dose flu shot at preventing influenza in adults age 50+. The relative efficacy rate was even higher for adults age 65+ (27.4%).⁶ Early clinical trials for the two COVID mRNA vaccines showed a minimum 94% efficacy in preventing infection and high efficacy in preventing severe disease, hospitalization, and death.⁷ For older Americans who already have an elevated risk, this level of protection can mean the difference between a mild infection and a life-threatening one.
2. Rapid vaccine development. Why are mRNA vaccines faster to develop? Since they don’t require the growth of live virus cultures in a lab—a very time-consuming process—these vaccines can be developed with much greater speed than traditional vaccines. Once the mRNA is designed and synthesized, it can be quickly mass-produced. This was an important advantage at the peak of the COVID pandemic, as the swift development of mRNA vaccines enabled a faster and more efficient national and global vaccination effort. For older adults, this means quicker access to critical protection during viral outbreaks.
3. Adaptability to different strains and pathogens. As viruses like COVID and the flu mutate, new variants can emerge that might make traditional vaccines less effective. One of the key advantages of mRNA vaccines is their adaptability. Because mRNA technology allows for faster vaccine development, scientists can quickly update the vaccine formula to target new variants. This is a valuable advantage for older adults, as it ensures they’re protected against the most current strains of the virus. The adaptability of mRNA vaccines also means they can potentially be used to target entirely different pathogens—even in one vaccine. 
4. Positive safety profile. Like all vaccines, mRNA vaccines must go through rigorous clinical testing and meet the FDA's high standards for safety, effectiveness, and manufacturing quality before they can be approved. The mFLUSIVA clinical trial found no major safety concerns with the vaccine. Some participants experienced temporary side effects, including arm soreness, fever, headache, fatigue, and muscle aches after vaccination. Pfizer-BioNTech’s COMIRNATY® and Moderna’s Spikevax® were thoroughly tested for safety through multiple phases of clinical trials before being approved for public use. The trials included tens of thousands of volunteers of all ages—including older adults and those with underlying health conditions—to ensure the vaccine is both safe and effective in all types of people. Since then, both COVID mRNA vaccines have been updated yearly to protect against current and emerging variants circulating in communities. They continue to be monitored for any rare side effects through ongoing safety surveillance systems.
   
   When it comes to mRNA vaccine safety, it's important to know the facts. Unlike some conventional vaccines, mRNA vaccines do not contain any live virus. mRNA vaccines do not alter your DNA. The mRNA enters cells and provides temporary instructions for making a harmless viral protein. It does not enter the cell's nucleus, where DNA is stored, and the mRNA is quickly broken down after delivering its instructions.
5. Fewer side effects for people who are immunocompromised. Older adults can be more sensitive to the side effects of traditional vaccines. mRNA vaccines have been found to have a favorable safety profile, with most side effects being mild and short-lived, such as soreness at the injection site, mild fatigue, fever, chills, and body aches. 

Note: There have been rare reports of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the pericardium, the sac-like tissue surrounding the heart) after receiving mRNA vaccines. Males between the ages of 12 and 24 are most impacted by these conditions (roughly 27 cases per million), and most of the affected patients had completed a two-dose primary series of an mRNA COVID vaccine before their diagnosis. Studies are currently underway to determine if there are long-term heart effects in people who have had myocarditis following an mRNA COVID vaccine.

In general, serious side effects related to mRNA vaccines are rare, and the protective benefits far outweigh the risks—especially for older people and those with underlying health conditions.

Get your updated vaccines today

CDC recommends everyone age 6 months and older get a flu vaccine each year, with only a few rare exceptions. Getting vaccinated is still the best defense against serious illness, hospitalization, and death from this virus.

It’s especially important if you:

• Are age 65 or older

• Have health conditions that raise your risk (e.g., cancer or diabetes)
• Live in a long-term care facility

NCOA advises older adults to talk with their doctor, pharmacist, or nurse about their personal health risks and get COVID, flu, and RSV vaccines for the best protection. "Preventing illness is easier than recovering from it," says Dorothea Vafiadis, NCOA Senior Strategist for Healthy Aging. "Vaccines can help lower your risk of major health complications and make it easier to stay active and maintain your independent as you age."

The flu and COVID vaccines will continue to be fully covered by Medicare and Medicaid with no out-of-pocket costs to beneficiaries.

You can be an inspiration and a role model by rolling up your sleeve to get your shots this fall. Encourage people you know to do the same. Sharing the facts about vaccines can help save lives—and we all have a part to play.

Need help getting a flu or COVID vaccine?

Find COVID and flu vaccination sites near you by contacting your health care provider or local pharmacy.

You can also:

• Dial 211 or reach out to your state health department.
• Reach out to organizations that support older adults and people with disabilities:
  • The Aging Network: 1-800-677-1116
  • Eldercare Locator: Search by ZIP code at eldercare.acl.gov
  • Disability Information and Access Line (DIAL): 1-888-677-1199 or email DIAL@n4a.org
  • Medicare hotline: 1-800-633-4227 (TTY 1-877-486-2048)

Sources

1. CDC National Center for Immunization and Respiratory Diseases. Current Epidemiology of COVID-19. June 25, 2025.

2. Centers for Disease Control and Prevention (CDC). People with Certain Medical Conditions and COVID-19 Risk Factors. Found on the internet at https://www.cdc.gov/covid/risk-factors/index.html

3. Centers for Disease Control and Prevention (CDC). Flu and People 65 Years and Older. Found on the internet at https://www.cdc.gov/flu/highrisk/65over.htm

4. CDC Morbidity and Mortality Weekly Report. Influenza-Associated Hospitalizations During a High Severity Season — Influenza Hospitalization Surveillance Network, United States, 2024–25 Influenza Season. September 11, 2025. Found on the internet at https://www.cdc.gov/mmwr/volumes/74/wr/mm7434a1.htm

5. CDC Flu Burden. 2024–2025 Influenza Season Summary: Severity, Disease Burden, and Burden Prevented. March 12, 2026. Found on the internet at https://www.cdc.gov/flu-burden/php/data-vis-vac/2024-2025-prevented.html

6. CIDRAP. Moderna announces promising efficacy results from mRNA flu vaccine trial. June 30, 2025. Found on the internet at https://www.cidrap.umn.edu/influenza-vaccines/moderna-announces-promising-efficacy-results-mrna-flu-vaccine-trial

7. Yahya F. Jamous, et. al. The Safety and Effectiveness of mRNA Vaccines Against SARS-CoV-2. Cureus. September 15, 2023. Found on the internet at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10588549/#REF12