About This Page
This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Annual influenza vaccine for all adults unless contraindicated; use age-appropriate product for adults >=65
- Tdap once in adulthood if not previously received, then Td or Tdap booster every 10 years; Tdap during every pregnancy at 27-36 weeks
- Recombinant zoster vaccine (Shingrix) 2 doses for adults >=50 and immunocompromised adults >=19
- Pneumococcal vaccination is recommended for all adults >=50 and adults 19-49 with risk conditions using current PCV-based schedules
- HPV vaccination through age 26 if not adequately vaccinated; shared decision-making age 27-45
Overview
Adult immunization questions on USMLE Step 2 CK test age cutoffs, pregnancy timing, immunocompromised contraindications, catch-up vaccination, and postexposure prophylaxis. The CDC adult schedule is updated regularly by ACIP, so the exam typically emphasizes durable principles: inactivated vaccines are generally safe in pregnancy and immunocompromise, live vaccines are contraindicated in pregnancy and severe immunocompromise, and missed vaccines should be caught up rather than restarted. Vaccine decisions are based on age, prior immunization, pregnancy, occupational exposure, travel, sexual risk, chronic disease, immunocompromising conditions, and asplenia.
Epidemiology
Vaccination prevents morbidity, mortality, hospitalization, congenital infection, and outbreaks. Adults often have lower vaccination coverage than children, particularly for zoster, pneumococcal, hepatitis B, and HPV catch-up. Disparities are driven by access, insurance, misinformation, language barriers, transportation, mistrust, and missed opportunities during routine visits. ACIP recommendations are population-level recommendations, but local epidemiology and product availability can affect implementation.
Eligibility and Contraindications
Symptoms
All adults need assessment of vaccine history at routine visits, hospital discharge, pregnancy care, immigration visits, and pre-travel consultation
Pregnancy: give Tdap during every pregnancy at 27-36 weeks; give inactivated influenza vaccine during flu season
Immunocompromise: avoid live vaccines such as MMR, varicella, and live attenuated influenza when severely immunocompromised
Asplenia or complement deficiency: meningococcal, pneumococcal, Hib, and influenza vaccination are high-yield
Healthcare personnel: ensure hepatitis B immunity, annual influenza vaccination, and immunity to MMR and varicella
Adults with unknown or incomplete vaccine records generally receive indicated vaccines rather than relying on uncertain history
Signs
Severe allergic reaction to a vaccine component or prior dose is a contraindication to that vaccine
Moderate or severe acute illness usually warrants deferring vaccination until improved; minor URI is not a reason to defer
Pregnancy is a contraindication to live vaccines but not to Tdap or inactivated influenza vaccine
Guillain-Barre syndrome within 6 weeks of certain vaccines is a precaution, especially for influenza and tetanus-toxoid vaccines
Assessment Before Vaccination
First-line
Vaccine historyCheck prior records, state immunization registry, childhood series, military/immigration records, and disease history. Do not restart a vaccine series because of long intervals
Pregnancy statusRelevant before live vaccines; Tdap and inactivated influenza are specifically recommended in pregnancy
Immunocompromise assessmentHIV status, transplant, chemotherapy, biologics, high-dose steroids, asplenia, complement inhibitor use, CKD, liver disease, and diabetes affect vaccine selection
Second-line
SerologyUseful selectively: hepatitis B surface antibody after vaccination in healthcare workers, dialysis, and immunocompromised patients; varicella or MMR immunity if uncertain and vaccination contraindicated
Risk factor reviewSexual risk, injection drug use, homelessness, incarceration, travel, occupational exposure, MSM status, and chronic liver disease influence hepatitis A/B, meningococcal, mpox, and other vaccines
Medication reviewBiologic therapy, chemotherapy, high-dose glucocorticoids, and complement inhibitors may require timing vaccines before immunosuppression
Specialist
Travel medicine consultationFor yellow fever, typhoid, Japanese encephalitis, rabies preexposure, polio booster, malaria prophylaxis, and destination-specific risks
Allergy/immunology inputFor suspected severe vaccine allergy, complex immunodeficiency, or need for supervised challenge/desensitization
Core Adult Vaccination Recommendations
CDC/ACIP Adult Immunization Schedule1
Vaccines recommended broadly by age
- Influenza: annually for all adults; high-dose, adjuvanted, or recombinant formulations are often preferred for adults >=65
- COVID-19: follow current CDC age- and risk-based schedule
- Tdap/Td: one Tdap if never received as adult, then Td or Tdap every 10 years; use Tdap for wound management if indicated
- Zoster recombinant vaccine: 2 doses for adults >=50, regardless of prior shingles; also for immunocompromised adults >=19
- Pneumococcal: PCV-based vaccination for adults >=50 and younger adults with risk conditions according to current CDC schedule
2
Vaccines based on age, risk, or shared decision-making
- HPV: vaccinate through age 26 if not adequately vaccinated; shared clinical decision-making age 27-45
- Hepatitis B: universal vaccination for adults 19-59; vaccinate adults >=60 with risk factors and offer based on patient preference
- Hepatitis A: chronic liver disease, homelessness, injection/non-injection drug use, MSM, travel, occupational risk, or patient request
- RSV: older adults and pregnancy indications depend on current ACIP guidance and product-specific recommendations
3
Special populations
- Pregnancy: Tdap every pregnancy at 27-36 weeks; influenza during season; COVID-19 per current guidance; RSV maternal vaccine when indicated by season and gestational age
- Asplenia: pneumococcal, MenACWY, MenB, Hib if not previously vaccinated, and annual influenza
- HIV/immunocompromise: avoid live vaccines when severely immunocompromised; give inactivated vaccines but anticipate lower response
- Healthcare workers: hepatitis B series and post-vaccination serology, annual influenza, MMR and varicella immunity, Tdap
4
Wound prophylaxis and catch-up principles
- Clean minor wound: tetanus booster if >10 years since last tetanus-containing vaccine
- Dirty or major wound: booster if >5 years since last tetanus-containing vaccine; add TIG if unknown/incomplete primary series
- Interrupted series: continue where left off; do not restart
- Live vaccines not given same day should generally be separated by at least 4 weeks
Complications
- Missed opportunities: Failure to vaccinate at routine visits, hospitalizations, pregnancy care, or chronic disease visits
- Contraindication errors: Live vaccines in pregnancy or severe immunocompromise can cause fetal or disseminated infection risk
- Reactogenicity: Local pain, fever, fatigue, and myalgias are common and usually self-limited
- Anaphylaxis: Rare but requires immediate recognition and epinephrine
- Outbreak risk: Low coverage enables influenza, measles, pertussis, meningococcal disease, and hepatitis A outbreaks
USMLE Step 2 CK Exam Tips
- 1Tdap is given during EVERY pregnancy at 27-36 weeks, regardless of prior Tdap history
- 2Live vaccines are contraindicated in pregnancy and severe immunocompromise; inactivated vaccines usually are not
- 3Shingrix is recombinant, not live — give at age >=50 and in immunocompromised adults >=19 when indicated
- 4Unknown vaccine records: vaccinate if indicated; do not restart a documented series because of delay
- 5Dirty wound + unknown tetanus history = tetanus vaccine plus tetanus immune globulin
- 6Asplenia = pneumococcal + meningococcal + Hib + influenza
- 7HPV routine catch-up through 26; age 27-45 is shared decision-making, not routine universal catch-up
- 8Minor illness without fever is not a contraindication to vaccination
practicetest your knowledge on immunization schedule (adult)Apply what you've learnt with USMLE Step 2 CK-style questions from the iatroX Q-Bank — preventive medicine and beyond.
open q-bank