Immunizations

Overview

• US-bound refugees are not required to receive vaccinations before arrival in the United States. Therefore many may not be fully up to date with Advisory Committee on Immunization Practices (ACIP)-recommended immunizations at arrival. However, most new arrivals receive some age-appropriate vaccinations through the overseas Vaccination Program for US-Bound Refugees.
• At the first domestic health visit, clinicians should review all available vaccine records, perform any testing, and update or revaccinate, as appropriate.
• Vaccine doses administered outside the United States should be accepted as valid, if schedules and doses are compatible with ACIP recommendations.
• Checking for laboratory evidence of immunity (i.e., antibody levels) is an acceptable alternative to vaccination, when previous vaccinations or disease exposure are likely. However, the clinician should be familiar with the efficacy and interpretation of available serologic tests when relying on testing as proof of immunity.
• Most refugees are familiar with the importance of vaccines and the need for boosters but may be less familiar with the need for primary care or other preventive health maintenance. Appointments for routine vaccinations may be helpful in establishing and ensuring longitudinal primary care services.

Background

US-bound refugees, unlike immigrants, are not required to receive vaccinations before arrival in the United States. Therefore, many may not be fully up to date with ACIP-recommended immunizations at time of arrival. Refugees may have received vaccines before their displacement, from programs run by countries of asylum (depending on healthcare access), through vaccination programs and initiatives in refugee camps, or during the overseas health assessment as part of the Vaccination Program for US-Bound Refugees. Additionally, in settings with vaccine-preventable disease outbreaks, refugees may be required to receive specific immunizations before travel to the United States.

Vaccination Program for US-Bound Refugees

US-Bound refugees are offered some vaccines overseas through the Vaccination Program for US-Bound Refugees. This program was initiated to protect health, prevent travel delays due to disease outbreaks, and allow for more rapid integration into schools after arrival in the United States. US-bound refugees at participating sites are offered 1–3 doses in each vaccine series, depending on age, availability of appropriate vaccines, time to departure, and logistics. First vaccine doses are given during the overseas medical screening examination, approximately 3–6 months before departure for most refugees. Second vaccine doses are typically given 1–2 months after the first doses. Refugees who undergo repeat medical examinations before departure may receive additional vaccine doses. Vaccinations administered through this program are documented on the DS-3025 (Vaccination Documentation Worksheet). Age-appropriate historical vaccinations with valid documentation are also recorded on the DS-3025 in the "Vaccination Record" column.

Evaluating Vaccination Records for Arriving Refugees

During the domestic medical screening, clinicians should:

1. Review the overseas vaccination records for dates of administration, intervals between doses, and age at the time of vaccination.
   1. The DS-3025 will include vaccines given as part of the overseas vaccination program and a record of valid, documented historical vaccines presented at the time of overseas health assessment. Generally, any vaccines documented on this form can be accepted as valid and count toward the refugee's US immunization record.
   2. Historical vaccination records may include camp vaccination cards, as well as records or booklets from other programs or clinics. Whenever possible, overseas panel sites document valid historical immunization records in the "History" section of the DS-3025. Historical records are more likely to predict protection if the documented vaccines, dates of administration, intervals between doses, and the person's age at the time of vaccination are comparable to ACIP recommendations.1 Some documented historical vaccinations may be incompatible with ACIP recommendations (e.g., measles-containing vaccines given before 1 year of age, or monovalent measles vaccines rather than the measles-mumps-rubella [MMR] combination vaccine). Verbal reports of prior vaccination should not be counted toward the routine immunization schedule. Only valid, documented vaccine doses should count toward the immunization schedule. Frequently, vaccine names are documented in languages other than English, or the names or components of vaccines may be unfamiliar to US clinicians. Language translations are available from the Immunization Action Coalition and the CDC Pink Book. The Immunization Action Coalition also has published a list of vaccine manufacturers and product information.
2. Determine which vaccines are due based on ACIP recommendations, age, and immunization history.
   1. Space vaccine doses appropriately, taking into account the correct intervals between any historically documented vaccines and those to be given at the domestic screening (e.g., two live injectable vaccines such as MMR and varicella should be given on the same day or separated by a minimum of 28 days).
   2. TST or IGRA tuberculosis test may be administered simultaneously with live vaccines or deferred for 28 days after vaccination1.
3. Determine whether revaccination is appropriate. Revaccination may be considered in some circumstances:
   1. Invalid or incorrectly documented historical vaccines (e.g., record indicates a vaccine dose was given before birth, taking into account possible transposition of month and day [dd-mm-yyyy])
   2. Clinician concerns about the validity of documented vaccines or falsification of records (rare)
   3. Severe pediatric malnutrition at time of immunization may impair adequate immune response. However, the immunology of malnutrition is poorly understood and data are limited. While most malnourished children can mount a protective immune response following vaccination, the timing, quality, and duration of their immune response may be diminished2. Some experts advise revaccination once the child's malnutrition has resolved.

Decisions about revaccination are best made after the options available for various vaccines are discussed with the patient and/or caregiver. Tables discussing approaches to revaccination, including checking for serologic evidence of immunity and "catch-up dosing" are provided by CDC and by the American Academy of Pediatrics Red Book. Clinicians should be aware that adverse events attributed to excess immunization are rare and generally mild. Local adverse effects or reactions are more common with certain vaccines. All adverse events should be reported to the Vaccine Adverse Event Reporting System.

Vaccination Administration

Vaccinations should be given in accordance with ACIP recommendations. Both adults and children should be evaluated and their vaccine needs addressed during the domestic screening visit. See the ACIP childhood immunization schedules (including catch-up schedules), and adult immunization schedules. Although there is no specific limit to the number of vaccines that may be given during one visit, the decision about how many vaccines to give at one time should be agreed upon by the patient (or patient's caregiver) and clinician. Combination vaccines can decrease the total number of injections and may be useful when administering catch-up vaccines. If the number of vaccines needed exceeds the number a patient is willing to receive at one time, the clinician may need to prioritize vaccines. Vaccine prioritization should be based on several factors including the patient's risk of contracting or spreading specific infections, the number of antigens in a vaccine (e.g., a single shot with antigens for five infections or a vaccine with a single antigen), and patient concerns about certain vaccines. The clinician also should consider the compatibility of vaccines (live-virus vaccines should be given concurrently or separated by 28 days), minimum dosing intervals, and the number of doses required to complete a series.

Patients should be assessed for any potential contraindications to vaccination, including severe allergic reactions to a vaccine or vaccine component. Pregnancy or certain immunocompromising medical conditions should also be considered before administering live vaccines. Additional vaccines may be recommended for patients with certain underlying medical conditions. See the recommended schedules by medical indication for adults and children.

Serologic Testing before Vaccination

If vaccination records are unavailable, an age-appropriate vaccination schedule should be initiated. However, serologic testing for immunity (i.e., antibody testing) is an alternative when the provider believes the refugee is likely to have had a previous infection that conveyed immunity or if they received a full series of vaccines that was not recorded.

Multiple factors influence the clinician's decision to check for serologic evidence of immunity before vaccination. Examples include:

• Cost of the vaccine course compared to serologic testing
• Likelihood of previous infection on the basis of the population prevalence or individual history
• Availability of antibody testing and acceptance that antibody presence confers immunity
• The number of doses needed to complete a series
• The level (titer) of antibody known to confer immunity
• The likelihood that the patient will return for results and further management

Healthcare professionals may choose to test for immunity in certain refugees (such as African adults who are likely to be immune to measles, mumps, and rubella, or hepatitis A). Cost-effectiveness will vary according to the prevalence of disease or immunity in the population, as well as the cost of serologic testing in different laboratories. More data are needed on population-specific vaccine-preventable disease prevalence rates to determine cost-effectiveness of serologic screening versus initiation of a vaccine schedule34. Clinicians should be familiar with the appropriate serologic tests to order and how to interpret the results.

Special Considerations

1. Hepatitis B Virus (HBV)

Most US-bound refugees are tested for HBV infection overseas using hepatitis B surface antigen (HBsAg). HBsAg results will be documented on the DS forms, typically in the remarks section of the DS-3026 (Medical History and Physical Examination Worksheet) and/or the DS-3025. HBsAg-positive persons do not receive HBV vaccination overseas. However, individuals are counseled about the infection and transmission prevention. HBsAg-negative persons are offered the hepatitis B vaccine. Most receive 2 doses before departure and may be due for the third dose after arrival. In this situation, serologic testing should not be performed. If serologic testing is performed, results should be interpreted with caution, as vaccination may cause temporary seroconversion (anti-HBs), which does not predict long-term protection. In addition, HBsAg testing should be delayed for at least 4 weeks after the final hepatitis B vaccination because the vaccine can cause a false positive HBsAg for up to 30 days. Therefore, serologic results can be difficult to interpret (and generally avoided) when an individual has received an incomplete hepatitis B vaccine series.

2. Varicella Serology

The epidemiology of varicella in international settings differs from that in the United States. The median age of varicella infection varies throughout the world but generally occurs later in life in the tropics than in temperate climates (most children will not be infected, and it is common to find nonimmune adolescents and adults). Serologic screening of newly arrived refugees for varicella immunity before vaccinating is cost-effective, especially in older adults56. Factors that commonly lead clinicians to vaccinate rather than screen for varicella antibody include:

• Exposure to a person with varicella or herpes zoster
• Younger age (6 years of age may be cost-effective in most populations tested5)
• Difficulty in arranging follow-up visits
• Inability or lack of mechanism to pay for the screening test
• School entry or work requirements

3. Hepatitis A Virus (HAV) Serology

Additionally, the epidemiology of HAV in international settings differs from that in the United States. Most children coming from areas highly endemic for hepatitis A (most refugee populations) will have been infected (with minimal or no symptoms) and will have immunity. In some situations, testing for HAV infection may be more cost-effective than the two-dose vaccine series, although delays in receiving results and logistical challenges of repeat visits should be considered.

4. Poliovirus Vaccination

All applicants for immigrant visas who are residents of or long-term visitors (i.e., >4 weeks) to countries identified to be infected with WPV1, cVDPV1, cVDPV2, or cVDPV3, with potential risk for international spread, are required to receive one dose of inactivated polio vaccine (IPV) within 12 months before travel to the United States. This requirement is outlined in the Addendum to Technical Instructions for Panel Physicians for Vaccinations: Polio. The countries listed in the addendum are based upon WHO recommendations and are updated regularly.

Those applying for US Refugee or Visa 92 or 93 status are not required to receive vaccinations before travel to the United States. However, they may receive overseas vaccinations through the Vaccination Program for U.S.-bound Refugees and Visa 93 Applicants. Additionally, some may be required to meet other vaccination requirements separate from the immigration medical exam.

CDC recommends that children and adults who were vaccinated against poliovirus outside the United States be fully protected against all three types of polioviruses. In the United States, IPV is the only polio vaccine recommended for routine immunization (see ACIP recommendations on Use of IPV). Oral polio vaccine (OPV) received on or after April 1, 2016, is bivalent (bOPV), only protecting against poliovirus types 1 and 3 and should not be counted toward primary series completion. If a person only received bOPV, they are not vaccinated against type 2 poliovirus, and they need to complete an IPV 3- or 4- dose series depending on their age to be fully protected. If documentation shows administration of age-appropriate vaccination with either IPV or trivalent OPV, then the person is considered fully vaccinated (see Routine Polio Vaccination).

If a person received fractional (1/5 full dose) IPV administered intradermally outside of the U.S., 2 fractional doses of IPV (fIPV) should be considered valid and counted as 1 full intramuscular dose of IPV towards the U.S. vaccination schedule. For more information on fIPV and countries that include fIPV as part of their routine immunization schedule, see Notes about fractional IPV doses.

Children and adolescents ≤ 18 years of age:

• CDC recommends that all children receive 4 doses of polio vaccine to protect against polio, or poliomyelitis, as part of the series of routine childhood vaccines.
• Children who are unvaccinated, lack documentation of vaccination, or have documentation that cannot be validated, should be revaccinated according to the U.S. schedule with the age-appropriate IPV (see Child and Adolescent Immunization Schedule).
• Children and adolescents aged 4 months through 18 years who are delayed in getting all recommended doses should complete their series by following the recommended catch-up schedule.
• Adolescents aged 18 years who completed the primary series and are at increased risk for poliovirus exposure, may be administered a single lifetime booster dose of IPV (see Child Immunization Schedule Notes).

Adults aged >18 years:

• CDC recommends that adults who are known or suspected to be unvaccinated or incompletely vaccinated, may be administered the remaining doses (1, 2 or 3 IPV doses) to complete a 3-dose primary series with IPV (see Adult Immunization Schedule Notes).
• Adults who completed the primary series and are at increased risk for poliovirus exposure, may be administered a single lifetime booster dose of IPV (see Adult Immunization Schedule Notes).

Follow-up Care

While ongoing preventative healthcare may be unfamiliar to some refugees, most will be familiar with the importance of vaccination. Routine vaccinations also provide a good opportunity to establish and assure ongoing primary care. Refugees should be assisted in scheduling follow-up visits to complete their vaccinations.

Adjustment of status to permanent resident alien ("green card") occurs one year after arrival in the United States. Proof of age-appropriate vaccination is required at the time of status adjustment. See the Vaccination Technical Instructions for Civil Surgeons for additional information on vaccination recommendations for adjustment-of-status applicants.