# Adult Immunization Strategies and Catch-Up Schedules

## Overview

Adult vaccination rates in the U.S. are significantly below Healthy People 2030 targets for most vaccines. Only ~50% of adults receive annual influenza vaccine; pneumococcal, shingles, and Tdap coverage remain suboptimal. ACIP (Advisory Committee on Immunization Practices) provides evidence-based recommendations for adult immunizations. New vaccines (RSV, updated COVID-19, updated pneumococcal) have expanded the adult immunization landscape. Preventive medicine physicians must be proficient in catch-up schedules, contraindications, and immunization for special populations (immunocompromised, pregnant, travelers)

## ACIP Adult Immunization Schedule (Key Vaccines)

### Influenza

Annual vaccination for all adults >=6 months (including pregnant women) Standard-dose inactivated (IIV4), recombinant (RIV4), or live attenuated (LAIV4, ages 2-49, non-pregnant) High-dose (Fluzone High-Dose) or adjuvanted (Fluad) preferred for adults >=65. Effectiveness varies by season (10-60%); greatest benefit in preventing severe illness and hospitalization.

### Tdap/Td

One dose Tdap for all adults who have not previously received it (regardless of interval since last Td) Td or Tdap booster every 10 years. Tdap during each pregnancy (27-36 weeks) Wound management: Tdap preferred if not previously received; Td acceptable for boost.

### MMR

Adults born in 1957 or later without evidence of immunity: 1 dose MMR. Two doses for healthcare workers, international travelers, and students at post-secondary institutions. Contraindicated in pregnancy and severe immunodeficiency. Evidence of immunity: documented vaccination, laboratory confirmation, or birth before 1957.

### Varicella

Two doses (4-8 weeks apart) for adults without evidence of immunity. Evidence of immunity: 2 documented doses, lab confirmation, U.S.-born before 1980 (except healthcare workers and pregnant women), or history of disease. Contraindicated in pregnancy and severe immunodeficiency (live vaccine)

### HPV (Gardasil 9)

Routine: ages 11-12 (2-dose series if started before age 15; 3-dose if started at >=15) Catch-up: through age 26 for all. Shared clinical decision-making: ages 27-45 (not routine; limited benefit if prior exposure) Not recommended after age 45. Contraindicated in pregnancy (defer doses until postpartum)

### Pneumococcal

**PCV20 (Prevnar 20)**: one dose for all adults >=65 and adults 19-64 with risk factors. **Alternative**: PCV15 followed by PPSV23 (>=1 year later) Risk conditions: chronic heart/lung/liver disease, diabetes, alcoholism, smoking, cochlear implant, CSF leak, immunocompromising conditions, asplenia, sickle cell. Simplified in 2023: PCV20 alone is preferred (replaces complex prior sequencing)

### Shingles (Recombinant Zoster Vaccine -- Shingrix)

Two doses (2-6 months apart) for all adults >=50. Also recommended for immunocompromised adults >=19. ~97% efficacy against shingles at age 50-69; ~91% at >=70; efficacy sustained through 10+ years. Replaces live zoster vaccine (Zostavax), which was discontinued. Can be given regardless of prior history of shingles or Zostavax vaccination.

### COVID-19

Updated (variant-adapted) COVID-19 vaccine recommended annually for all adults >=6 months. Additional doses for immunocompromised individuals. mRNA (Pfizer, Moderna) or protein subunit (Novavax) options. Schedule varies by prior vaccination history and immune status.

### RSV

RSV vaccine (Abrysvo or Arexvy) for adults >=60 through shared clinical decision-making. Single dose; targets RSV seasons. Also approved for pregnant women at 32-36 weeks (Abrysvo) to prevent infant RSV.

### Hepatitis B

Universal vaccination for all adults 19-59 (2022 ACIP update) Adults >=60: shared clinical decision-making (with risk factor-based recommendation) Options: Engerix-B/Recombivax HB (3-dose), Heplisav-B (2-dose, ages >=18), PreHevbrio (3-dose) Heplisav-B: higher seroconversion rates, especially in immunocompromised and older adults.

### Hepatitis A

Not universally recommended for all adults (unlike HepB) Recommended for: travelers to endemic areas, MSM, persons who use drugs, persons with chronic liver disease, persons experiencing homelessness, HIV-positive individuals. Two-dose series (0, 6-12 months) or combination HepA-HepB (Twinrix, 3-dose)

### Meningococcal

**MenACWY**: routine for first-year college students living in dorms (if not previously vaccinated at >=16); recommended for asplenia, complement deficiency, HIV, travel to meningitis belt. **MenB**: shared clinical decision-making for ages 16-23 (preferred 16-18); recommended for asplenia, complement deficiency, outbreak settings. **Pentavalent MenABCDWY (Penbraya)**: FDA-approved 2023; single-product coverage of all five serogroups.

| Vaccine | Target Population | Schedule | Key Notes |
|---|---|---|---|
| Influenza | All adults annually | 1 dose/year | High-dose or adjuvanted preferred for ≥65 |
| Tdap/Td | All adults; each pregnancy | Tdap ×1, then Td/Tdap q10yr; Tdap 27-36 wks each pregnancy | Wound management: Tdap if not previously received |
| PCV20 | Adults ≥65; 19-64 with risk | 1 dose | Preferred over PCV15 + PPSV23 sequence |
| Shingrix (RZV) | Adults ≥50; immunocompromised ≥19 | 2 doses (0, 2-6 months) | ~97% efficacy ages 50-69; non-live |
| HPV (Gardasil 9) | Through age 26 (routine); 27-45 (shared decision) | 2-dose (<15) or 3-dose (≥15) | Not recommended after 45 |
| Hepatitis B | All adults 19-59; ≥60 shared decision | 2-dose (Heplisav-B) or 3-dose | Universal adult recommendation since 2022 |
| COVID-19 | All adults annually | Updated variant-adapted dose | Additional doses for immunocompromised |
| RSV | Adults ≥60 (shared decision); pregnant 32-36 wks | 1 dose | Abrysvo for both adult and maternal indications |
| MenACWY | College students; asplenia; complement deficiency | 2 doses (booster at 16) | Travel to meningitis belt |
| MenB | Ages 16-23 (shared decision); asplenia | 2 or 3 doses (product-dependent) | Pentavalent MenABCDWY now available |

## Special Populations

### Immunocompromised Patients

**Avoid live vaccines**: MMR, varicella, LAIV, live zoster (Zostavax) Shingrix (recombinant, non-live) IS recommended for immunocompromised adults >=19. Additional pneumococcal and meningococcal doses may be needed. COVID-19: additional primary and booster doses recommended. Hepatitis B: check anti-HBs titers after vaccination; Heplisav-B may provide better response. Timing: ideally vaccinate before immunosuppression; if on immunosuppressive therapy, response may be blunted.

### Pregnant Women

**Recommended**: Tdap (27-36 weeks each pregnancy), inactivated influenza, COVID-19, RSV (Abrysvo, 32-36 weeks seasonal) **Contraindicated**: live vaccines (MMR, varicella, LAIV, live zoster); HPV (defer) **If indicated**: Hepatitis A, Hepatitis B, pneumococcal, meningococcal (inactivated) are safe.

### Healthcare Workers

Required/strongly recommended: annual influenza, Tdap, MMR (2 doses), varicella (2 doses or titer), Hepatitis B (with titer confirmation) COVID-19: per facility policy. TB screening: per occupational health protocol.

### Travelers

Destination-specific: yellow fever (live vaccine), typhoid, Japanese encephalitis, rabies pre-exposure, meningococcal (meningitis belt) Routine catch-up: ensure all age-appropriate vaccines are current. Hepatitis A: for all travelers to endemic areas. Malaria chemoprophylaxis (not a vaccine): separate consideration.

<image>A comprehensive adult immunization schedule chart organized by vaccine (rows) and age group (columns: 19-26, 27-49, 50-64, >=65). Each cell is color-coded: green for routine recommendation, yellow for shared clinical decision-making, orange for risk-based, and red for contraindicated. Vaccines include influenza, Tdap, MMR, varicella, HPV, PCV20, Shingrix, COVID-19, RSV, HepB, HepA, and meningococcal. Adult immunization schedule education illustration.</image>

<image>A flowchart for pneumococcal vaccination in adults showing two pathways: (1) PCV20 alone (preferred, one dose) or (2) PCV15 followed by PPSV23 (>=1 year later). Entry criteria branch into adults >=65 (routine) and adults 19-64 with risk conditions (list provided). Previously vaccinated individuals have a separate pathway showing how to complete the series. Pneumococcal vaccination algorithm education illustration.</image>

<image>An infographic showing adult vaccination coverage rates compared to Healthy People 2030 targets for key vaccines: influenza (~50% vs. 70% target), Tdap (~40% vs. 90%), shingles >=50 (~35% vs. 50%), pneumococcal >=65 (~65% vs. 90%), and HPV series completion ages 19-26 (~60% vs. 80%). Bars show the gap between current coverage and targets, with annotations about disparities by race, insurance status, and geography. Adult immunization coverage education illustration.</image>

## Clinical Pearls

Shingrix is a recombinant (non-live) vaccine and CAN be given to immunocompromised patients -- this is a common point of confusion; Zostavax (live) was contraindicated, but Shingrix is specifically recommended for immunocompromised adults >=19. PCV20 has simplified pneumococcal vaccination -- one dose for adults >=65 or those 19-64 with risk conditions replaces the complex prior PCV13/PPSV23 sequencing. HPV vaccination through shared clinical decision-making for ages 27-45 is generally of limited benefit -- most adults in this range have already been exposed to vaccine-type HPV; the greatest population benefit comes from vaccinating at ages 11-12. For boards: know the adult schedule by age group, live vaccine contraindications (pregnancy, immunocompromised), the pneumococcal algorithm, and Tdap timing in pregnancy (27-36 weeks each pregnancy) Adult vaccination rates remain far below targets for most vaccines -- systems-level interventions (standing orders, EHR reminders, pharmacist-administered vaccines) are more effective than clinician reminders alone.

## References

- CDC. Recommended Adult Immunization Schedule, United States, 2024-2025. MMWR. 2024.
- Dooling KL, et al. Recommendations of the Advisory Committee on Immunization Practices for use of recombinant zoster vaccine. MMWR. 2018;67(3):103-108.
- Kobayashi M, et al. Use of 15-valent and 20-valent pneumococcal conjugate vaccines among U.S. adults: ACIP recommendations. MMWR. 2023;72(RR-3):1-39.
- Meites E, et al. Human papillomavirus vaccination for adults: ACIP recommendations. MMWR. 2019;68(32):698-702.
- Lu PJ, et al. Surveillance of vaccination coverage among adult populations -- United States, 2022. MMWR Surveill Summ. 2023.