Getting older brings changes to our health, including how our bodies respond to infections. Our immune systems naturally change with age, making it harder to fight off certain illnesses. Infections like the flu, respiratory syncytial virus (RSV), and pneumonia can become more serious as we get older, even for people who are otherwise healthy.
Vaccines for older adults are an important part of preventive healthcare. But as our immune systems change, so can our response to vaccination. Understanding these changes can help explain why certain vaccines are recommended at different ages and why researchers continue to study ways to improve protection.
How Does Aging Affect the Immune System?
Our immune systems work every day to protect us from viruses, bacteria, and other germs. As we age, some of the cells responsible for recognizing and fighting infections become less effective.
Scientists call this process immunosenescence. These changes don’t affect everyone in exactly the same way, but they can make it harder for older adults to fight certain infections or develop a strong immune response after vaccination.
Researchers are learning more about why this happens. A 2025 study published in Nature, highlighted by Gavi, the Vaccine Alliance, examined how certain immune cells change with age. The findings may help explain why some vaccines produce weaker responses in older adults.
This research could eventually help scientists develop vaccines better suited to aging immune systems.
Why Are Vaccines Important for Older Adults?
An illness that causes mild symptoms in one person can be much more serious for someone else. Age is one of several factors that can influence how severely an infection affects the body.
Take influenza, for example. While many people recover from the flu within a week or two, older adults are more likely to experience complications that require medical attention or hospitalization.
According to the Centers for Disease Control and Prevention (CDC), adults ages 65 and older face a higher risk of serious flu complications. This is partly due to age-related changes in immune defenses.
Vaccination can reduce the risk of certain infections and lower the chances of severe illness.
Research highlighted by Gavi in 2026 reviewed evidence on influenza, COVID-19, and RSV vaccines, reinforcing their role in reducing serious respiratory illness and hospitalization.
What Vaccines Do Older Adults Need?
Vaccination recommendations change as we get older. Your healthcare provider can help determine which vaccines are appropriate based on your age, medical history, and previous vaccinations.
Here are several vaccines that are particularly relevant for older adults.
Influenza (Flu) Vaccine
Flu viruses change from year to year, which is why annual vaccination is recommended. Getting a flu vaccine can reduce your risk of getting sick and may help prevent serious complications if you do become infected.
For adults ages 65 and older, the CDC preferentially recommends high-dose, recombinant, or adjuvanted flu vaccines. These options may provide better protection than standard-dose flu vaccines for this age group.
If one of these preferred vaccines isn’t available, the CDC recommends receiving another age-appropriate flu vaccine rather than going without vaccination.
Respiratory Syncytial Virus (RSV) Vaccine
RSV is a common respiratory virus that often causes cold-like symptoms. However, it can lead to more serious infections, including pneumonia, in older adults and people with certain health conditions.
The CDC recommends a single dose of RSV vaccine for all adults ages 75 and older and adults ages 50–74 who are at increased risk of severe RSV illness.
Unlike the flu vaccine, RSV vaccination is not currently recommended every year.
Pneumococcal Vaccine
Pneumococcal bacteria can cause pneumonia and other serious infections, including bloodstream infections and meningitis.
The CDC recommends pneumococcal vaccination for adults ages 50 and older, with specific recommendations depending on their vaccination history and health conditions.
Shingles Vaccine
Shingles is caused by the same virus responsible for chickenpox. It can cause a painful rash and, in some cases, nerve pain that continues long after the rash has healed.
The CDC recommends two doses of the shingles vaccine for adults ages 50 and older, as well as adults ages 19 and older who have weakened immune systems because of certain medical conditions or treatments.
Other immunizations, including COVID-19 and tetanus-containing vaccines, may also be recommended based on individual circumstances.
How Clinical Research Is Improving Vaccines for Older Adults
Vaccines have helped prevent infectious diseases for generations, but there is still more to learn about how they work in older adults.
One challenge researchers face is that aging immune systems don’t always respond to vaccines as strongly as younger immune systems. This has led scientists to explore different vaccine formulations, doses, and approaches that may improve protection.
Some vaccines already reflect this research. For example, certain flu vaccines recommended for adults 65 and older are designed to produce a stronger immune response.
Researchers are also studying new vaccines and ways to improve existing ones. These studies help scientists understand how the immune system responds to vaccination, how long protection may last, and whether different approaches could work better for specific populations.
Clinical trials are an important part of this process. Volunteers help researchers evaluate investigational vaccines and gather information about their safety and effectiveness.
Frequently Asked Questions About Vaccines and Aging
Do vaccines work as well in older adults?
Vaccines can still provide important protection as we age, although immune responses may be weaker in some older adults. Certain vaccines, including specialized flu vaccines for adults ages 65 and older, are designed to help improve protection in this age group.
Do older adults need a flu vaccine every year?
Yes. The CDC recommends annual flu vaccination for everyone ages 6 months and older, with rare exceptions. Because flu viruses change and protection can decrease over time, getting vaccinated each season helps maintain protection.
Can I participate in a vaccine clinical trial if I’ve already been vaccinated?
Possibly. Every clinical trial has different eligibility requirements. Some studies may allow participants who have received certain vaccines, while others may have restrictions based on vaccination history or timing. The research team can help determine whether you may qualify.
Are vaccines safe for people with chronic health conditions?
Many vaccines are recommended for people with chronic conditions because they may be at greater risk of serious illness from certain infections. However, recommendations vary depending on the condition, treatment, and type of vaccine. Your healthcare provider can help determine which vaccines are appropriate for you.
Staying Up to Date on Vaccinations
It’s easy to lose track of which vaccines you’ve received or when you might need another dose. Recommendations can also change as new research becomes available.
If you haven’t reviewed your vaccination history recently, consider discussing it with your healthcare provider. They can help identify any vaccines you may need based on your age and individual health risks.
You can also review the CDC’s recommended adult immunization schedule for additional information.
Vaccines are just one part of staying healthy as we age, but they can make a meaningful difference in reducing the risk of preventable illness.
Explore Vaccine Clinical Trials at Rochester Clinical Research
Interested in learning more about vaccine research? Rochester Clinical Research is participating in clinical studies focused on preventing infectious diseases, including:
These studies help researchers evaluate investigational vaccines and other approaches to preventing illness. Opportunities vary by location, and each study has its own eligibility requirements.
Participation in clinical research is voluntary. Investigational vaccines and preventive treatments are being evaluated for safety and effectiveness and may not provide protection against illness.
Sources
Gavi, the Vaccine Alliance. (2025). This discovery could make vaccines more effective for older adults. Read article.
Nature. (2025). Peer-reviewed research on age-related changes in immune cells and vaccine responses. Read study.
Gavi, the Vaccine Alliance. (2026). Major evidence review confirms influenza, COVID-19 and RSV vaccines are safe and effective. Read article.
Centers for Disease Control and Prevention. Flu and People 65 Years and Older. Read CDC guidance.
Centers for Disease Control and Prevention. RSV Vaccine Guidance for Adults. Read CDC guidance.
Centers for Disease Control and Prevention. Pneumococcal Vaccination for Adults. Read CDC guidance.
Centers for Disease Control and Prevention. Shingles Vaccination. Read CDC guidance.
Centers for Disease Control and Prevention. Recommended Vaccinations for Adults. Read CDC schedule.
