The Basics of Pediatric Immunizations

Pediatric Immunizations

In the early 1950s there were four vaccines routinely used in the United States: diphtheria, tetanus, pertussis, and smallpox. Three of these vaccines (diphtheria, tetanus, and pertussis) were combined into a single shot (DTP). Children received five shots by the time they were 2 years old and not more than one shot at a single visit.^[3]

By the mid 1980s, there were seven vaccines routinely given to children: DTP; measles, mumps, rubella (MMR); and polio (smallpox was discontinued in the early 1970s). DTP and MMR were given in two shots, and polio vaccine was given by mouth. Children still received five shots by the time they were two years of age and not more than one shot at a single visit.

Since the mid-1980s, several vaccines have been added to the schedule. Haemophilus influenza B vaccine (Hib) was added in the mid 1980s; Hib was originally given in a single dose to toddlers and then as a series at two, four and six months. In the 1990s, hepatitis B and varicella (chicken pox) vaccines were added, and the polio vaccine shot (IPV) replaced the oral polio vaccine. Then, in 2000, the pneumococcal conjugate vaccine (PCV) was added and hepatitis A was recommended to children in high-risk areas. Table 1 provides information about the vaccine-preventable diseases, including type of organism, incidence for the year 2000, mode of transmission, symptoms, and complications.

As a result of the many additions and multiple doses required for most vaccines, the vaccine schedule has become very complicated. Now children may receive as many as 20 shots by two years of age and up to five shots in a single visit. By age two, children born today will have three doses of hepatitis B, four doses of DTP, four doses of Hib, three doses of polio, four doses of PCV, one dose of MMR, and one dose of chicken pox vaccine. At around four to six years they will be given booster doses of DTP and polio and second doses of MMR and chicken pox. This information is summarized in Table 2 .

Vaccines are also recommended for teens. Depending on which immunizations they received when they were younger or other factors (such as contracting chicken pox as a child), they will need vaccinations for chicken pox, hepatitis B, MMR, and diphtheria-tetanus (pertussis is not recommended after age 7). Additionally, many colleges are recommending, and some even requiring, that college students receive vaccination against meningococcal diseases.

In many public health clinics or school systems, immunizations are given under standing orders of the chief public health officer of a given state or another designated medical professional. Immunizations given in private practice are administered as any medication, under the orders of a treating provider. The National Childhood Vaccine Injury Act of 1986,^[8] requires that "informed consent" be obtained from the legal representative of a child receiving any vaccine. Informed consent is very specifically stipulated to include the provision of standardized "Vaccine Information Sheets" (VIS) to parents or guardians. These VIS are available on the CDC's website^[9] or through a local public health office.

Documentation that is required includes: date the vaccine is given; vaccine manufacturer; vaccine lot number; name, address, and title of the person giving the vaccine; and the date of the edition of the vaccine information materials that were provided. A parent signature is not required by law, but is customary in the documentation of the immunization. This information must be maintained in permanent medical records. Official vaccine information cards have been established in each of the 50 States, US territories, and the District of Columbia. These cards are personal medical records that assist the client in providing documentation of immunization status for schools and child-care centers and should be established for every newborn.

Vaccine manufacturers provide detailed recommendations for storage and handling of their products. Most vaccines require cold storage and some require freezing, while freezing damages many. All have a shelf life indicated by an expiration date. Live attenuated virus vaccines (eg, MMR, Varicella, and Yellow Fever) are sensitive to increased temperature and all others are sensitive to freezing. Failure to meet storage and handling recommendations could reduce potency of a vaccine, resulting in an inadequate immune response on the part of the recipient.

Manufacturer's package inserts also describe the expected appearance of a vaccine. All vaccines should be inspected on receipt and again before administration, even though it is not always possible to tell on visual inspection if a vaccine has been mishandled. Any vaccine dose that has been inadvertently given under questionable storage circumstances should not be counted as a true dose.^[10] Vaccines that require reconstitution should be reconstituted exactly according to manufacturer's instructions and given immediately after reconstitution. Vaccines that are distributed in multidose vials can be administered once opened, until their expiration date, given proper storage and the scrupulous use of sterile technique.

Vaccine recommendations are based on risk of exposure and burden of disease, balanced against any possible untoward effects of a particular immunobiologic. The Advisory Committee on Immunizations (ACIP) of the Centers for Disease Control and Prevention (CDC) and the American Academy of Family Physicians (AAFP) devises immunization standards in the United States. Recommendations for immunization are made with respect to the nature of the immunobiologic, the immunocompetence of the recipient, the age-specific risk for the disease, disease complications, and the potential interference with an immune response by passively transferred maternal antibodies. Vaccines are recommended for the youngest age group at risk for the disease for which efficacy and safety have been demonstrated.^[10] The childhood immunization schedule approved by the ACIP and AAFP in 2003 can be viewed at https://www.cdc.gov/nip/recs/child-schedule.pdf.^[11] This schedule is revised yearly and published every January.

Recommendations for administration and spacing of vaccines are devised to ensure optimal protection and efficacy and so should be followed carefully. There are times, however, modifications to the schedule are required. For example there may be a need to accelerate the schedule (eg, impending travel, being behind schedule), and a minimum interval between doses is provided in the immunization schedule. The recommendation allows for doses given within four days of the recommended minimum interval to be considered acceptable. Doses given in intervals more than four days shorter than recommended cannot be counted as valid doses to complete a series. Any repeat doses should be given four weeks after the invalid dose with consideration of the minimum age for the child. Certain vaccines, such as adult TD, pediatric DT, and tetanus toxoid can produce increased rates of local or systemic reactions if given too frequently.^[10]

The safety and efficacy of simultaneously administered vaccines (ie, at the same visit) is well supported by research.^[12,13,14] Recommendations for nonsimultaneous administration of vaccines vary with the vaccines to be given. Inactivated vaccines do not interfere with other inactivated vaccines or with live vaccines. It is permissible to give inactivated vaccine before, with, or after any inactivated or live vaccine. It is thought, however, that the immune response to one live vaccine may be impaired if administered within 30 days of another live vaccine.^[10] The plan should be to give the needed live vaccines at the same time or at least 30 days apart for optimal response. In the case of lapsed vaccination status, an attempt should be made to bring the client "up to date" using the minimum spacing intervals. When there is no documentation of immunization status, the client should be started on an age-specific schedule and be brought up to date as soon as possible.

The American Academy of Pediatrics (AAP) recommends that preterm and low- birth-weight infants be immunized at the usual chronological age. Doses of vaccine should not be reduced despite the size of the infant. There is some indication that very-low-birth-weight infants have a reduced immune response. The AAP reports that there are some studies that indicate lower rates of seroconversion among infants less than 2 kg who have been immunized against hepatitis B at birth. The optimal time to initiate hepatitis B immunization for low-birth-weight infants has not yet been determined. However, preterm infants with birth weights less than 2 kg, who have HB-sAg-positive mothers, should be immunized within 12 hours of birth with HBIG.^[5]

Internationally adopted children should be provided immunizations appropriate to US recommendations. Comparisons of immunization materials between countries should be made, as all vaccines of a type are not necessarily interchangeable. That is, if an international immunization record lists a measles vaccine, for example, care should be taken to discover the specific product used and to compare it to the US product for equivalency.

Contraindications and precautions are circumstances in which a vaccine should not be given. A contraindication is a condition in the client that increases the risk for a serious adverse reaction. A precaution is a condition in the client that might increase the risk for a serious adverse reaction or that might compromise the client's response to the vaccine. These circumstances are most often temporary and usually only result in delay of immunization. The CDC states that the only absolute contraindication for immunization is the known severe allergic reaction to a previous dose of a given vaccine or vaccine constituent. National standards for contraindications and precautions are updated yearly along with the immunization schedule.^[10] Providers should review these recommendations for precautions and contraindications periodically.

Vaccines for active immunization are administered to essentially well individuals. In many cases this can be a somewhat subjective decision. Minor illnesses such as colds are usually not a contraindication to vaccine administration. Children who are actively ill and significantly febrile should have immunization delayed if possible. This is due to concerns about an adequate immune response by the client, more than concern for potential vaccine injury.

Decisions to vaccinate immunocompromised children must be made individually. Severely immune-deficient persons should not receive live vaccines, as there is a true risk of disease. Persons with lesser degrees of immunodeficiency might benefit from killed vaccines and immune globulin. There is no increased risk of complications, though the benefit is unknown. In children with a secondary immune suppression, adequate immune response is usually reestablished within three months of cessation of immunosuppressive therapy.^[5] Vaccination can then be initiated or resumed at that time.

Breastfeeding is not considered a contraindication to vaccination in any situation. Neither inactivated nor live vaccine administered to a breastfeeding mother affect the safety of breast milk. Likewise, breastfeeding does not limit immune response on the part of the infant or toddler.^[15,16]

Administration of vaccines should employ infection control measures and sterile technique. Recommended routes of injection and needle length are always given by the manufacturer and have been a part of the research on the vaccine. These recommendations should always be followed, as should precautions related to age. For infants, the anterolateral aspect of the thigh should be used for injection; for toddlers and older children, the deltoid may be used if muscle mass is adequate^[5,10] and if institutional policies permit. Jet injectors, needle-free devices that deliver a narrow stream of vaccine that penetrates the skin, can deposit vaccine into intradermal, subcutaneous, or intramuscular tissue. Jet injectors have been proven to be safe and effective delivery systems with comparable rates of immune response in recipients.^[17]

NAINR. 2004;4(1) © 2004 W.B. Saunders

Cite this: The Basics of Pediatric Immunizations - Medscape - Feb 01, 2004.