Immunization in Children PDF

Immunization in Children Dr. Lamis Aziz Hameed Immunization Immunization is defined as the procedure by which the body is prepared to fight against a specific disease. It is used to induce the immune resi...

Immunization in Children Dr. Lamis Aziz Hameed Immunization Immunization is defined as the procedure by which the body is prepared to fight against a specific disease. It is used to induce the immune resistance of the body to a specific disease. Immunization is of two types: 1. Passive immunization 2. Active immunization Passive Immunization Passive immunization or immunity is produced without challenging the immune system of the body. It is done by administration of serum or gamma globulins from a person who is already immunized (affected by the disease) to a non-immune person.Passive immunization is acquired either naturally or artificially. Examples – gamma globulin for hepatitis or measles protection, tetanus Ig, rabies Ig Protects for short period, usually months only Maternal passive immunity is important for protecting infants until their own immune system is mature enough to protect them. Artificial passive immunity is conferred by the injection of antibodies generated by a different person or animal, or artificially in the laboratory. This type of immunity is useful for providing immediate protection against acute infections like tetanus, measles, etc. Active Immunization Active immunization or immunity is acquired by activating immune system of the body. Body develops resistance against disease by producing antibodies following the exposure to antigens. Active immunity is acquired either naturally or artificially. Examples – polio, diphtheria, pertussis, measles Active natural immunization Naturally acquired active immunity involves activation of immune system in the body to produce antibodies. It is achieved in both clinical and subclinical infections. Active artificial immunization Active artificial immunization is a type of immunization that is achieved by the administration of vaccines or toxoids. Vaccines Vaccine is a substance that is introduced into the body to prevent the disease produced by certain pathogens. Vaccine consists of dead pathogens or live but attenuated (artificially weakened) organisms. The vaccine induces immunity against the pathogen, either by production of antibodies or by activation of T lymphocytes. *** Edward Jenner produced first live vaccine. He produced the vaccine for smallpox from cowpox virus. Vaccination The process of distributing and administering vaccines is referred to as vaccination Significance: 1.Reduce the mortality and morbidity of infectious diseases 2. Eradication of certain diseases, such as smallpox, polio 3. Decreased transmission of other diseases such as pertussis, measles, hepatitis B 4. Improvement in national economy – less health care cost caring for sick children, less time off work of parents Types of vaccine 1. Live=attenuated (weakened) vaccines These vaccines contain modified strains of a pathogen (bacteria or viruses) that have been weakened but are able to multiply within the body and remain antigenic enough to induce a strong immune response. Advantage: Single dose is sufficient for immunization Generally must be refrigerated to preserve potency The vaccine should be cooled from the time of production to the time of administration “cool chain” Example – oral polio, measles, varicella Heterologous vaccines A subgroup of live attenuated vaccines produced from strains that are pathogenic in animals but not in humans. Examlpe: cowpox vaccine that protects against smallpox in humans. 2. Killed-inactivated vaccines To produce this type of vaccines, bacteria or viruses are killed or inactivated by a chemical treatment or heat. This group includes for example the inactivated poliovirus (IPV) vaccine, pertussis vaccine, rabies vaccine, or hepatitis A vaccine. Repeated dosing is required. 3. Sub-unit vaccines Instead of the entire microbe, subunit vaccines include only the antigens that best stimulate the immune system. In some cases, theses vaccines use epitopes: the very specific parts of the antigen that antibodies or T cells recognize and bind to. Because subunit vaccines contain only the essential antigens and not all the other molecules that make up the microbe, the chances of adverse reactions to the vaccine are lower. Eg: Hepatitis B vaccine 4. Toxoid vaccines These vaccines are used when a bacterial toxin is the main cause of illness. When the immune system receives a vaccine containing a harmless toxoid, it learns how to fight off the natural toxin. E.g. Vaccines against diphtheria and tetanus. Type Vaccine Live, attenuated Measles, mumps, rubella(MMRcombined vaccine) Varicella (chickenpox) Rota virus, OPV, influenza (nasal spray) Inactivted/killed Polio (IPV) Hepatitis A Toxoid (inactivated toxin) Diphtheria, tetanus Subunit/conjugate Hepatitis B Influenza (injection) Haemophilus influenza type b (Hib) Pertussis Pneumococcal Meningococcal Periods of maintained immunity due to vaccines: Short period (months): cholera vaccine Two years: TAB vaccine (typhoid-paratyphoid A and B vaccine) Three to Five years: DPT vaccine Five or more years: BCG Ten years: yellow fever vaccine Solid immunity: measles, mumps, and rubella vaccines Practical aspects of immunization 1. An In-activated live virus vaccines can be administered simultaneously at different sites without interference with immune response. 2. Two or more killed antigens may also be given simultaneously or at any interval between the doses. Exception Cholera and Yellow fever- 4 weeks gap 3. A minimum interval of 4 weeks is required between administration of two live antigens (if not administered simultaneously) 4. Lapse of schedule of immunization does not necessitate reinstitution of the total course. If OPV 2nd dose missed or delayed, can be continued. 5. Following are not contraindications: 1. mild acute illness 2. low grade fever 3. mild diarrheal disease 4. current antibiotic therapy 5. prematurity 6. recent exposure to an infectious disease 7. history of allergens e.g. Penicillin 8. Malnutrition 6. If immunization status of a child is unknown, there is no harm in giving appropriate vaccines again. 7. It is desirable not to reduce the dose of vaccine as it may cause inappropriate immunological response. Dose should not be exceeded to avoid side effects. 8. Measles, mumps and rubella vaccines should not be given to children, who were given immune globulin within the previous three months, since this may hinder adequate response to active immunization. 9. Live virus vaccines of all types and BCG should not be given to patients with congenital disorders of immune functions. 10. Children suffering from progressive neurological disorders or with history of convulsion to a previous dose are at high risk of adverse reactions following whole cell pertussis vaccine. Immunogenic and protective efficacy Immunogenic efficacy of a vaccine refers to its ability to induce an immune response. Protective efficacy refers to actual protection against disease. In case of killed bacterial vaccines and BCG, antibody response almost always results in protection. The breakthrough disease after immunization is indicative of vaccine failure. When the administration of recommended doses of vaccine does not result in immune response sufficient to protect against disease, the vaccine failure is primary. When disease occurs in spite of immune response, it is referred to as secondary vaccine failure Immunological adjuvants Are substances given along with antigens in order to enhance their immunogenic efficacy. Aluminum salts are used as adjuvants in diphtheria-pertussis-tetanus vaccines. Vaccine Age of administration Route of administration BCG At birth Intradermal Hepatitis B At birth intramuscular st OPV AT birth, 2, 4,6 ,18 months (1 booster), Oral nd 4-6 years (2 booster) Pentavalent (DPT, 2,4,6 months Intramuscular Hep B, Hib) PCV 2,4,6 months Intramuscular Rota virus 2,4 months Oral IPV (injectable polio vaccine) 3,6 months Intramuscular Measles 9 months Subcutaneous MMR 12, 18 months Subcutaneous DPT (booster doses) 18 months, 4-6 years Intramuscular BCG Vaccination BCG –Protects against tuberculosis, primarily in children Type – live bacterial vaccine Freeze dried (lyophilized) and stored at 4 C. After reconstitution, shelf life is 1-2 weeks. UV light kill the organisms rapidly. Route- ID over deltoid muscle. After 2-3 weeks, a papule develops- heals to scar, local LNs can enlarge. 4-12 weeks after immunization Tuberculin test becomes positive. 60 – 80% effective in preventing TB in infants, but protection decreases significantly after 2-3 years. Much less effective in adults. Timing- Any time after birth since mother's immunity not transferred to fetus. Side effect- Disseminated BCG infection (Axillary LN suppuration) Triple vaccine - DPT -Protects against diphtheria, tetanus and pertussis -Type; D toxoid, T toxoid, P inactivated bacterial antigen -Require minimum of three doses and one booster dose for full immunization. -Efficacy – 90% Adverse effects 1. Fever and malaise – up to 30% of children. 2. Swelling at injection site – can be minimized by deep IM injection. 3. Rarely – convulsions, prolonged crying, unresponsiveness Hepatitis B Type- Conjugate protein Requires total of 3 doses Adverse effects- mild fever and soreness at injection site If mother is HBsAg (+), administer HBV and HBIg (0.5mL) within 12 hours of life. If HBsAg status is unknown, administer HBV within 12 hours of birth and determine mother’s HBsAg HAEMOPHILUS INFLUENZAE TYPE B CONJUGATES VACCINE - Polysaccharide-protein conjugate vaccine - Three to four doses are required (at age two, four, six and 12–15 months of age. Efficacy- more than 95% - Adverse events- are uncommon. The most common reactions are local reactions at the injection site, and fever ROTAVIRUS VACCINE (RV) Indicated for the prevention of rotavirus gastroenteritis Live attenuated vaccine The monovalent human rotavirus vaccine (RV1) is given as a two-dose series with the first dose administered beginning at 6 weeks of age and the second dose administered not later than 24 weeks of age. The pentavalent human bovine rotavirus vaccine (RV5) is given as a three-dose series with the first dose given between 6 weeks to 14 weeks of age and the third dose administered not later than 32 weeks of age. The minimum interval between doses is 4 weeks. ***There is insufficient data on efficacy and safety of rotavirus vaccines given in older age groups. Efficacy- 85%-98% protective against severe rota virus disease Side effects: A small increase in intussusception cases during the first week after the first dose. Stomach pain, vomiting, blood in the stool, weakness, irritability. MEASLES/MMR Given subcutaneously (SC) - Live attenuated Children who received a dose of a measles-containing vaccine at less than 12 months of age should be given 2 additional doses beginning at 12 through 15 months of age and separated by at least 4 weeks, the latter two preferably as MMR. **Measles vaccine may be given as early as 6 months of age in cases of outbreaks as declared by public health officials. Minimum age of MMR is administered at age 12 months. Children 12 months of age and older should receive two doses of MMR vaccine separated by at least 28 days. Oral polio -Protects against polio, given by oral administration -Live, attenuated (weakened) virus -Requires minimum of three doses and one booster dose for maximum public immunity -Efficacy – 95% -Adverse effects very rare incidence of vaccine related polio (< 1 per million children) Injectable polio vaccine Type: inactivated poliovirus Doses of IPV: four doses at these ages: 2 months, 4 months, 6-18 months, and a booster dose at 4-6 years. PNEUMOCOCCAL CONJUGATE VACCINE (PCV) Protects against pneumococcal disease , or pneumonia Three doses are recommended for infants at 2,4 and 6 months of age Given intramuscularly 60 – 70% effective in preventing invasive disease Side effects of this vaccine include decreased appetite, slightly raised temperature, irritability, redness and swelling at injection site Serious side effects are rare and include *a high temperature and possibly febrile convulsion * Allergic reactions Immunization contraindications & precautions: Contraindications (general for all routine vaccines 1. Anaphylactic reaction to a vaccine contraindicates further doses of that vaccine. 2. Anaphylactic reaction to a vaccine constituent contraindicates the use of vaccines containing that substance. 3. Moderate or severe illness with or without fever. 4. Immunodeficiency disease including AIDS. BCG Immunodeficiency disease including AIDS DTaP/DTP Contraindications 1.DTP should not be given to children older than six years of age. Instead of DTP Td or aP are suitable for those children 2. Encephalopathy within 7 days of administration of previous dose Precautions: 1. Temp. of > 40.5 C within 48 hr 2. Convulsions within 3 days 3. Persistent, inconsolable crying lasting > 3 hr. within 48 hr. 4. Guillian-Barre syndrome within 6 wk after a dose OPV Contraindications 1. Infection with HIV or a household contact with HIV infection. 2. Known immunodeficiency (hematologic and solid tumors; long-term immunosuppressive therapy) 3. Immunodeficient household contact MMR Contraindications 1. Severe allergic reaction/anaphylaxis after a previous dose or after one of the components of the vaccine (e.g., gelatin, neomycin) 2. Pregnancy 3. Known immunodeficiency 4. Immunosuppressive therapy, HIV infection with evidence of immunosuppression Precautions 1.Recent administration of a blood (< 11 months) product or immune globulin preperation 2. Thrombocytopenia 3. History of thrombocytopenic purpura Hepatitis B Contraindications Severe allergic reaction to previous dose or vaccine component. precautions 1.Infant weighing < 2,000 grams 2.Moderate or severe acute illness with or without fever  Rota virus Contraindications 1. Severe allergic reaction to a previous dose 2. Children younger than six weeks of age 3. Moderate or severe acute illness Hib Contraindications 1.Allergy after getting a dose of the vaccine 2. Immunodeficiency syndrome IPV: is contraindicated if patient has developed severe adverse effect to its use in the past. PCV: Severe allergic reaction after a previous dose