How immunity ages
The immune system ages like every other organ. The thymus, where T cells mature, shrinks with age. The supply of "naive" T cells that can respond to new threats dwindles, while the body fills with memory cells tuned to old infections. At the same time, a low-grade, body-wide inflammation called inflammaging sets in. A 2023 review links these changes, together called immunosenescence, to more frequent and severe infections, weaker responses to vaccines, and more age-related disease and cancer.
Two practical consequences follow. First, infections that a 30-year-old shrugs off, such as flu, RSV, and pneumonia, become leading causes of hospitalization and death after 65. Second, standard vaccines work less well in older bodies, which is why there are high-dose and adjuvanted (boosted) versions for people 65 and older. Healthy habits matter, but none replaces vaccination. Why aging happens at all is covered in The science of aging.
Why vaccines are a longevity tool
Vaccines prevent the infection they target, and several appear to do more.
- Shingles and dementia. In natural experiments in Wales, Australia, and Canada, people who became eligible for shingles vaccination had fewer new dementia diagnoses; in Wales, about 20% fewer over seven years. The details are in Brain health.
- Flu and the heart. In a meta-analysis of six randomized trials with 9,001 people, flu vaccination cut major cardiovascular events from 5.4% to 3.6%, a 34% relative reduction. The benefit was concentrated in people with a recent heart attack or unstable angina; in other participants the trials showed no clear effect.
- RSV in older adults. Respiratory syncytial virus causes an estimated 60,000 to 160,000 hospitalizations and 6,000 to 10,000 deaths a year among Americans 65 and older, a burden in the same range as flu.
- Measles is back. The US recorded 2,289 measles cases in 2025 and 4,588 in 2026 as of October 22. Adults born in 1957 or later who are unsure of their immunity should check.
Most recommended vaccines are covered without cost-sharing, common side effects such as a sore arm or a day of fatigue pass quickly, and the protection is largest for the oldest and sickest.
What changed in US vaccine policy
For more than 60 years, the CDC's Advisory Committee on Immunization Practices (ACIP), an independent expert panel, reviewed evidence and voted on recommendations, and the CDC adopted them into yearly schedules. Insurance coverage, and pharmacy rules in some states, follow ACIP. Since 2025 that system has been disrupted. The key events, as summarized by the Congressional Research Service and later reporting:
| Date | Event |
|---|---|
| April 2025 | ACIP recommends RSV vaccine for adults 50 to 59 at increased risk; this remains in effect |
| May 2025 | HHS Secretary Robert F. Kennedy Jr. announces the CDC will stop recommending COVID-19 vaccines for children and pregnant women |
| June 9, 2025 | All 17 ACIP members are removed and new members appointed |
| June 2025 | New ACIP votes to stop using flu vaccines containing the preservative thimerosal |
| September 2025 | ACIP moves COVID-19 vaccination for all ages from routine to individual decision-making |
| December 2025 | ACIP moves the infant hepatitis B vaccine, including the birth dose, from universal to individual decision-making |
| January 2026 | HHS issues a new childhood schedule with fewer routinely recommended vaccines |
| March 16, 2026 | A federal court in American Academy of Pediatrics v. Kennedy stays the new ACIP members' appointments, all their votes after June 11, 2025, and the 2026 childhood schedule |
| October 6, 2026 | A federal appeals court hears HHS's appeal; ACIP has not met since the ruling and has issued no guidance for the 2026–27 season |
The result, as of October 2026: the CDC's posted adult schedule is the July 2025 version, and the stayed votes have no effect for now. Separately, the FDA since 2025 has approved COVID-19 vaccines only for people 65 and older and for younger people with at least one condition that raises their risk; the FDA label describes who a product is approved for, not who should get it. Several medical societies now publish their own recommendations: the American Academy of Family Physicians (AAFP) for adults, the American College of Obstetricians and Gynecologists (ACOG) for pregnancy, and the Infectious Diseases Society of America (IDSA) for people with weakened immune systems. The American College of Physicians (ACP) formally supports the AAFP and ACOG schedules.
The adult vaccine schedule
This table gives the optimal plan. It follows the CDC's posted 2025 schedule and its detailed notes, with the 2026–27 AAFP guidance where it adds to it; where the optimal plan goes further, the Notes column gives the guideline minimum.
| Vaccine | Who | When | Notes |
|---|---|---|---|
| Flu | Everyone 19 and older | Every year, ideally September or October | At 65+, high-dose, adjuvanted, or recombinant preferred |
| COVID-19 | Adults 19 and older | Each season's updated vaccine | 65+: two doses, 6 months apart; FDA label covers 65+ or high risk under 65 |
| RSV | 75 and older; 50 to 74 at increased risk; consider from 60 if healthy | One dose | Not repeated; 60 to 74 without risk factors is a shared decision (AAFP) |
| Pneumococcal | 50 and older; 19 to 49 with risk conditions | Once: PCV20 or PCV21 (or PCV15 then PPSV23 a year later) | If you only had PCV13, one PCV20 or PCV21 dose a year later |
| Shingles (Shingrix) | 50 and older; 19+ with weakened immunity | Two doses, 2 to 6 months apart | No upper age limit |
| Tdap / Td | All adults | Tdap once, then Td or Tdap every 10 years | Tdap in every pregnancy, weeks 27 to 36 |
| HPV | Through 26; through 45 if you may have new partners | Two or three doses, depending on starting age | Guideline: routine through 26, shared decision 27 to 45 |
| Hepatitis B | All adults who are not immune | Two, three, or four doses, by product | Guideline: routine 19 to 59; 60+ with risk factors or on request |
| Hepatitis A | All adults who are not immune | Two doses (three with the combined A and B vaccine) | Guideline: with risk factors (travel, liver disease, HIV, drug use, homelessness) or on request |
| MMR | Born in 1957 or later without evidence of immunity | One or two doses | Proof is a vaccine record or a blood test |
| Chickenpox | Born in 1980 or later without evidence of immunity | Two doses | Not for people with weakened immunity |
| Others | By risk: meningococcal, mpox, Hib, polio, travel vaccines | Varies | Ask your doctor or a travel clinic |
Flu
Get a flu shot every year; the virus changes and protection fades within months. For adults 65 and older, the CDC prefers high-dose, adjuvanted, or recombinant vaccines. The AAFP adds Moderna's mRNA flu vaccine, mFlusiva, which the FDA approved in August 2026 for people 50 and older, to that preferred list. In a Spanish trial of 103,169 adults aged 65 to 79, high-dose vaccine cut flu or pneumonia hospitalizations by 23.7% compared with standard dose, while a Danish trial of 332,438 people missed its main endpoint; the benefit of the enhanced products is real but modest Moderate. Don't delay vaccination waiting for a preferred product. People 65 and older should avoid July and August shots, because protection wanes before the season ends. The June 2025 vote against thimerosal-containing vials is stayed; large studies have found no harm from those amounts.
COVID-19
As of October 2026, the CDC's posted schedule recommends COVID-19 vaccination for adults (the stayed September 2025 vote would have made it an individual decision), and the AAFP recommends an updated vaccine for all adults, especially those 65 and older, those at increased risk, and anyone never vaccinated. Adults 65 and older should get two doses each season, six months apart. The 2026–27 vaccines target the XFG variant of the JN.1 lineage. Current vaccines protect much better against severe disease than against infection, and protection against infection fades within months. The evidence is strongest for adults 65 and older and those at high risk Strong. If you are a healthy adult under 65, you are outside the FDA label; the AAFP notes that most adults qualify for at least one listed risk condition (such as obesity, physical inactivity, or past smoking) and can self-attest, and that vaccinating outside the label is within normal medical practice.
RSV
A single dose of RSV vaccine is recommended at 75 and older, and from 50 to 74 if you are at increased risk: chronic heart or lung disease, diabetes with complications, kidney failure, severe obesity, weakened immunity, nursing home residence, or frailty Strong. Three products are available (Arexvy, Abrysvo, mResvia), with no preference among them. Revaccination is not recommended yet. Post-licensure monitoring found a small excess of Guillain-Barré syndrome, about 18 cases per million doses for one product type, far smaller than the risk from RSV in high-risk older adults.
From 60, even if you are healthy, consider it Moderate. Every RSV vaccine is FDA-approved for everyone 60 and older, and in the main trial of 24,966 adults 60 and older, one dose cut RSV lower respiratory illness by 82.6% over the first season. The AAFP's 2026–27 guidance calls vaccination at 60 to 74 without a risk condition a shared decision, within the label. The trade-off: only one dose is recommended for now, so a healthy 62-year-old who uses it may have less protection at 80, when RSV is most dangerous, unless boosters are later approved, and the small Guillain-Barré risk counts for more when your own RSV risk is low. Check coverage first, since some plans pay only for the routine groups.
Pneumococcal
Pneumococcus causes pneumonia, bloodstream infections, and meningitis. Since October 2024, everyone 50 and older is recommended to get one dose of a conjugate vaccine, PCV20 or PCV21, which completes the series; PCV15 is followed by PPSV23 a year later. Younger adults with diabetes, heart, lung, liver, or kidney disease, smoking, or weakened immunity also qualify Strong.
Shingles
About 1 in 3 Americans will get shingles, a painful reactivation of the chickenpox virus that can leave months or years of nerve pain (postherpetic neuralgia). Two doses of Shingrix, 2 to 6 months apart, are about 97% effective in adults 50 to 69 and 91% in those 70 and older, with protection staying high for at least seven years Strong. Adults 19 and older with weakened immunity should also get it. A sore arm, and for some people a day of feeling unwell, is common after each dose. The possible dementia benefit (see Brain health) is an added reason not to wait.
Tetanus, diphtheria, and pertussis
Get one dose of Tdap as an adult if you never had it, then a Td or Tdap booster every 10 years, and Tdap during each pregnancy (preferably weeks 27 to 36) to protect the newborn from whooping cough Strong. A deep or dirty wound may call for an earlier booster.
HPV
HPV causes almost all cervical cancers and many throat, anal, and genital cancers. Get vaccinated through 26 if you were not vaccinated as a child Strong. From 27 to 45, the optimal choice is to get it too if you may have new sexual partners Moderate: it cannot clear an infection you already have, but it protects against the types you have not yet met, and the vaccine is approved through 45. Guideline minimum: the CDC makes 27 to 45 a shared decision with your clinician, because many people that age have already been exposed to some HPV types. Cancer screening is in the cancer chapter.
Hepatitis A and B
The optimal plan is simple: if a blood test or your records do not show immunity, get vaccinated against both, at any adult age Strong. Hepatitis B spreads through blood and sex and causes liver cirrhosis and cancer; hepatitis A spreads through contaminated food and water, and a combined vaccine covers both. Guideline minimum: since 2022, hepatitis B vaccination has been recommended for all adults 19 to 59, and for those 60 and older with risk factors or who ask for it; hepatitis A is recommended for people with travel plans, chronic liver disease, HIV, drug use, or unstable housing, and for anyone who wants protection.
MMR and chickenpox
If you were born in 1957 or later and have no record of two MMR doses or a blood test showing immunity, get vaccinated; people born before 1957 are presumed immune. If you were born in 1980 or later and have never had chickenpox or its vaccine, get two doses. Both are live vaccines and not given to people with severely weakened immunity or during pregnancy.
Travel and other vaccines
Meningococcal, Hib, polio, and mpox vaccines are recommended for specific risk groups, such as people without a working spleen, certain lab workers, and people at risk of mpox exposure. For international travel, check the CDC's Travelers' Health destination pages and see a travel clinic well before departure, since some vaccines (such as hepatitis A, typhoid, or yellow fever) need time or multiple doses. If you have a weakened immune system, the IDSA 2025 guidelines cover COVID-19, flu, and RSV vaccination specifically.
Infection screening
Several chronic infections cause no symptoms for years while they damage the liver, immune system, or other organs. All of the infections below are curable or controllable once found, and the tests are cheap blood or urine tests, so the optimal plan tests everyone at least once and repeats with any new risk.
| Test | Optimal plan | Guideline minimum | Source |
|---|---|---|---|
| HIV | Every adult at least once, at any age; again with each new partner; every pregnancy | Once from 15 to 65, older or younger if at risk | USPSTF 2019, grade A |
| Hepatitis C | Every adult at least once, at any age; repeat with ongoing risk | Once from 18 to 79 (CDC: all adults) | USPSTF 2020, grade B; CDC |
| Hepatitis B | Every adult once, with a three-part blood panel | Same (CDC); USPSTF: only adults at increased risk | CDC 2023; USPSTF 2020 |
| Chlamydia and gonorrhea | Women 24 and younger who are sexually active, regularly; anyone with a new or multiple partners | Women 24 and younger, and older women at increased risk | USPSTF 2021, grade B |
| Syphilis | With each new partner or other risk | Periodically, at increased risk | USPSTF 2022, grade A |
| Latent tuberculosis | Once, if you were born in or lived in a country where TB is common, or lived or worked in a shelter or prison | Same | USPSTF 2023, grade B |
Hepatitis C is now curable with 8 to 12 weeks of pills, so a positive test is good news compared with finding out after cirrhosis. The CDC's hepatitis B panel also shows whether you are immune or need vaccination. For men, the USPSTF found evidence insufficient to recommend routine chlamydia and gonorrhea screening; testing after a new partner is the sensible default. Men who have sex with men should follow the CDC's schedule of at least yearly testing for HIV, syphilis, chlamydia, and gonorrhea, every 3 to 6 months at higher risk, and anyone at ongoing risk of HIV should ask about preventive medication (PrEP), which the USPSTF recommends (grade A). The HIV screening recommendation is being updated as of October 2026.
Everyday infection prevention
- Wash your hands. Scrub with soap for at least 20 seconds after using the toilet, before eating or cooking, and after caring for someone sick; use sanitizer with at least 60% alcohol when soap isn't available Moderate.
- Use the CDC's layered approach to respiratory viruses. The core steps are staying up to date on vaccines, hand hygiene, cleaner indoor air, and staying home when sick. Masks, distancing, and testing are extra layers for when illness is rising or you are at high risk. Ventilation and air filtering are covered in Avoiding harm.
- Get treated early if you are at high risk. The CDC advises people with risk factors for severe illness to seek care promptly, since treatment may lower the risk; antivirals for flu and COVID-19 are started within days of symptoms. If you are 65 or older or have a chronic condition, test early and call your doctor.
- Handle food safely. The CDC's four steps are clean, separate, cook, and chill: cook poultry to 165°F (74°C), ground meat to 160°F (71°C), and whole cuts and fish to 145°F (63°C); refrigerate leftovers within 2 hours (1 hour above 90°F); keep the fridge at 40°F (4°C) or below. More in Nutrition.
Long COVID
Long COVID is a set of symptoms that persist or begin after a SARS-CoV-2 infection. In 2024 the National Academies defined it as an infection-associated chronic condition lasting at least three months, which can follow asymptomatic, mild, or severe infection, does not require a positive test, and affects children as well as adults.
The scale is large: a 2024 review estimated about 400 million cases worldwide and an economic cost near $1 trillion a year. Suspected mechanisms include persisting virus, immune dysregulation, mitochondrial dysfunction, blood vessel inflammation, and microbiome changes, but none is settled, and research into treatments is still early. The honest guidance is limited: avoid infection where you reasonably can, stay current on vaccination, and if symptoms last more than a few weeks, see a clinician to rule out other causes and ask about a long COVID clinic.
Using antibiotics well
The CDC estimates that at least 28% of outpatient antibiotic prescriptions are unnecessary. Antibiotics kill bacteria, not viruses, so they do nothing for colds, flu, COVID-19, or most sore throats, sinus infections, and bronchitis. Antibiotics can cause side effects, from rashes and diarrhea to serious gut infections, and every unnecessary course adds to resistance that makes future infections harder to treat. Ask "Is this bacterial, and what happens if we wait?" When you do need antibiotics, take them exactly as prescribed, and don't save leftovers for later.