Vaccinations are one of the most effective methods of disease prevention, drastically reducing illness, hospitalizations, and deaths from infectious diseases. In order to prevent a resurgence of vaccine-preventable illnesses in the US, the Centers for Disease Control and Prevention (CDC) and Advisory Committee on Immunization Practices (ACIP) publish yearly immunization schedule recommendations. These schedules are formulated based on extensive research and aim to protect individuals at the age at which they have the highest risk for infection. Specific recommendations are available for the general population (children and adults), individuals with certain health conditions, and those traveling to areas with high rates of infection. Education on the importance of vaccination and the implementation of catch-up schedules for underimmunized individuals are vital to ensuring and preventing infectious diseases.
Routine immunization 
- Immunizations are a vital component of primary prevention; see “Pathogens affecting unvaccinated individuals.”
- Follow the recommended ACIP immunization schedules.
- Age-appropriate vaccines should be administered at the same visit when feasible; see simultaneous vaccination and combination vaccines.
- Be aware of . 
- Identify individuals with risk factors and/or medical indications that necessitate altered immunization schedules.
- See “Immunization schedule by medical indication.”
- See the “Special patient groups” section
- Educate individuals on the disease that each vaccine aims to prevent and the possible adverse effects; provide Vaccine Information Statements.
- Report any vaccine-related adverse events to the Vaccine Adverse Event Reporting System (see “Tips and links”).
Vaccine dose is not adjusted for weight but may vary based on age.
Vaccinations against multiple diseases at the same visit 
Administration of > 1 vaccine on the same day, but in different syringes and at different anatomical locations
- May include a combination of inactivated vaccines, live attenuated vaccines, or immunoglobulins
- Most vaccines can be administered simultaneously; exceptions include:
If injectable or nasally administered live vaccines are not administered on the same day, they must be administered ≥ 4 weeks apart. 
Combination of different vaccine components in a single product
- Preferred over simultaneous single-component vaccines, when feasible
- Examples of commonly used combination vaccines:
- MMRV 
Timing and spacing of vaccines 
- Follow the ACIP recommendations for the minimum age for the first dose and minimum intervals between doses to ensure optimal protection.
- Unapproved delayed or alternate immunization schedules put individuals at risk.
Delayed or missed vaccines (undervaccination) 
- Follow recommended undervaccinated individuals. for
- Do not restart the immunization series from the beginning.
- Continue with the next dose in the immunization series.
Vaccines administered before the recommended minimum age or interval 
In general, any vaccine administered ≥ 5 days earlier than the minimum age or interval is considered invalid and needs to be repeated.
- First dose administered ≥ 5 days earlier than the recommended minimum age
- Repeat the dose when or after the individual attains the minimum recommended age.
- For live vaccines, repeat the first dose ≥ 28 days after the invalid first dose.
- Additional doses administered ≥ 5 days earlier than the recommended minimum interval
- Repeat the dose; the minimum interval restarts from when the invalid dose was administered.
Doses administered ≤ 4 days before the minimum age or interval (grace period) are considered valid. 
Overview of ACIP immunization schedule 
Routine immunization schedule
Catch-up immunization schedule and immunization schedule by medical indication
Hepatitis B vaccine
Tetanus, diphtheria, and acellular pertussis vaccines
Diphtheria, tetanus, acellular pertussis vaccine
|Tetanus, diphtheria, acellular pertussis vaccine (Tdap) |
and tetanus, diphtheria vaccine (Td)
|Inactivated poliovirus vaccine (IPV)|| |
|Rotavirus vaccine (RV)|| || |
|Haemophilus influenzae type b vaccine (Hib vaccine)|| || |
| || |
|Hepatitis A vaccine (HepA vaccine)|| |
| Measles, mumps, rubella vaccine (MMR) |
Measles, mumps, rubella, varicella vaccine (MMRV)
| || |
|Varicella vaccine (VAR)|| || |
|Human papillomavirus 9-valent vaccine (HPV vaccine)|| || || |
|Meningococcal vaccines||Meningococcal conjugate vaccines (MenACWY vaccines)|| || |
|Meningococcal B vaccine (MenB vaccine)|| |
|Pentavalent meningococcal vaccine (MenABCWY vaccine) || |
| Zoster recombinant vaccine (RZV) |
| || |
|Influenza vaccine || || |
COVID-19 vaccines 
|Pfizer-BioNTech COVID-19 vaccine|| || |
|Moderna COVID-19 vaccine|| |
|Novavax COVID-19 vaccine|| |
|Dengue vaccine |
|Respiratory syncytial virus vaccine || |
The use of combination vaccines can decrease the number of injections needed at each encounter. Combination vaccines are frequently used for the 2-month, 4-month, 6-month, and 4–6-year immunizations. They may also be used for catch-up immunizations.
|Immunizations at each health maintenance or well-visit encounter |
|Newborn follow-up at 2 weeks|
|15 months|| |
|24, 30, and 36 months|| |
|6–10 years|| |
|12–15 years|| |
- Adjustments to the routine immunization schedule are needed for certain indications. 
- An overview of recommendations for vaccinating preterm infants, pregnant individuals, and those with HIV infection is detailed in this section.
- See “Immunization schedule by medical indication” and the latest CDC recommendations for adjustments in:
- Patients with any of the following:
- Health care personnel
- Men who have sex with men
Immunizations in individuals with HIV 
- Inactivated vaccines are generally safe.
- If feasible, vaccination of individuals with HIV should be done before they become immunosuppressed.
- The immune response may be diminished if a vaccine is administered during a period of intense immunosuppression.
- See the latest CDC recommendations for details.
Exceptions to the routine immunization schedule
Varicella vaccine, MMR vaccine, and dengue vaccines
- Contraindicated in individuals with CD4 percentage < 15% or CD4 count 200 cells/mm3 or an AIDS-defining condition.
- In individuals with CD4 is ≥ 15% or 200 cells/mm3 for ≥ 6 months:
- Influenza vaccine
- 2 doses, 2–6 months apart (regardless of previous history of shingles)
- Minimum age for first dose: ≥ 19 years of age
- HPV vaccine: Use a 3-dose series regardless of age at first immunization.
- Rotavirus vaccine: Use with caution in infants.
- Refer to the latest CDC recommendations for adjustments to the immunization schedule for: 
Immunizations in preterm infants 
- Premature infants weighing < 2 kg at birth should receive the first Hep B vaccine at 1 month or at hospital discharge, whichever is first. 
- Preterm infants should receive all other recommended vaccinations according to chronological age unless contraindicated.
Immunizations in pregnancy and lactation 
Prior to pregnancy 
- Recommend all routine .
- Assess for rubella, and hepatitis B, . ; 
- Recommend influenza vaccination (especially if pregnancy is expected during flu season). 
During pregnancy 
For all pregnant individuals, recommend:
- Tdap vaccine once every pregnancy, preferably at 27–36 weeks' gestation 
- RSV vaccine between 32–36 weeks' gestation 
- Inactivated influenza vaccine during flu season (safe in all trimesters) 
Consider additional immunizations based on risk factors, e.g.: 
Avoid contraindicated immunizations.
- Live attenuated vaccines are contraindicated as they carry a theoretical risk of fetal infection (e.g., congenital rubella syndrome; , congenital varicella syndrome). 
- Vaccines lacking safety data in pregnant individuals: HPV vaccine, RZV, certain HepB vaccines (i.e., Heplisav-B and PreHevbrio) 
After pregnancy and/or during lactation 
Lactation is not a contraindication for most vaccines.
- If live attenuated vaccines were deferred during pregnancy, administer them postpartum.
- Contraindicated: smallpox vaccine 
- Avoid the yellow fever vaccine unless the benefits outweigh the risks.
Immunizations for health care personnel (HCP) 
- All HCP should receive routine and catch-up vaccinations according to the .
- In HCP who do not have evidence of pathogen-specific immunity , the following vaccines are recommended:
Additional vaccines in high-risk groups 
- Individuals with 
- HCP who work with individuals at risk for HAV infection : Hepatitis A vaccine is recommended.
- Laboratory workers who handle highly infectious pathogens: Additional vaccinations and/or boosters against specific pathogens are recommended.
- HCP planning travel abroad: Relevant travel vaccinations should be completed prior to travel.
Verify immunization requirements with the local occupational health department.
Immunizations in men who have sex with men 
- Compared to other forms of unprotected sex, unprotected anal sex has the highest risk of HIV transmission. 
- Routine and catch-up vaccinations should be given according to the , especially:
- Adjustments to the immunization schedule may be required if additional risk factors are present.
Immunizations in adults ≥ 50 years of age 
- All adults ≥ 50 years of age
- Adults ≥ 60 years of age: Consider the RSV vaccine in individuals with risk factors for severe RSV infection; use shared decision-making. 
- All adults ≥ 65 years of age: pneumococcal vaccine
Immunizations before travel
- Ensure individuals are up-to-date on age-appropriate immunizations; see ACIP immunization schedule.
- If not already received, recommend HepA vaccine and HepB vaccine.
- Based on travel destinations (see the CDC's Travelers' Health website in “Tips and links”):
- Administer any additional immunizations required.
- Prescribe prophylactic medications as necessary (e.g., ).
- Consider additional protective measures, e.g.:
- Prescribing medication that may be required (e.g., antibiotics to treat )
- Counseling on and
Immunizations are not effective immediately, and certain malaria prophylaxis must be initiated 1–2 weeks before traveling to high-risk areas. 
Overview of immunizations before travel
This table provides an overview of the pretravel immunizations recommended for individuals from the United States who are planning international travel.
|Overview of travel immunizations |
|Immunization||Schedule||Minimum age||Risk areas||Recommendation||Other considerations|
Meningococcal conjugate vaccine 
| || || |
| || || |
|Japanese encephalitis vaccine || || |
Yellow fever vaccine 
| || || || |
Rabies vaccine 
| || || || || |
|IPV)  (|| || || || |