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IMMUNIZATION

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IMMUNIZATION

Immunization is the process of inducing immunity against a specific disease.

Immunity can be induced either passively through administration of antibody-containing preparations or actively by administering a vaccine or toxoid to stimulate the immune system to produce a prolonged humoral and/or cellular immune response.

Immunization

It is the process of rendering a subject immune by inoculating with a specific antigen.

It is the method of choice for prevention of infectious disease.

Goal of Immunization

The immediate goal of immunization is to prevent disease in individuals, but the ultimate goal is to eliminate or even eradicate a communicable disease.

As a result of effective and safe vaccines, smallpox has been eradicated, polio is close to worldwide eradication, and measles and rubella are no longer endemic in the U.S.

Immunization

Active immunity

Passive immunity

Herd immunity

Active immunity

Active immunization involves administration of all or part of a micro-organisim or modified product of that micro-organisim(eg.  a toxoid, a purified antigen ,or an antigen produced by genetic engineering) to evoke an immunologic response mimicking that of natural infection but that usually presents little or no risk to the recipient.

Passive immunity

Passive immunization entails administration of preformed antibody to a  recipient.

This produces immediate protection, which only lasts for some weeks or months, until donated antibodies are broken down or used up by the individual

Herd immunity

Herd immunity exists if the number of people in a community who have active immunity against an infection exceeds a critical level.

If these level is achieved then even non-vaccinated individuals are protected from getting the disease.

In this way transmission falls or stops without universal immunity.

Vaccine

Vaccines are defined as whole or parts of microorganisms administered to prevent an infectious disease.

The vaccine is usually  a protein similar to part of a virulent infectious organism that can be recognized by the individual’s immune system, which then produces antibodies or cell mediated immunity against the antigen in the vaccine.

Types of Vaccine

Live attenuated vaccines

Killed, or inactivated vaccines

Conjugated vaccines

Toxoid vaccines

Genetically engineered vaccines

Live attenuated vaccines

Live attenuated vaccine is one, which produces active immunity by causing a mild infection.

A virulent organism is weakened so that it produces an antigenic response without the serious consequences of a wild organism.

Live attenuated vaccines

BCG

Polio drops

MMR

Yellow fever

Killed, or inactivated vaccines

Killed, or inactivated vaccine is prepared from virulent organisms  or preformed antigen inactivated by heat, phenol, formaldehyde or some other means.

Killed, or inactivated vaccines

Pertussis

Cholera

Influenza

Injectable polio

Rabies

Conjugated vaccines

The response to polysaccharide vaccine is incomplete and unreliable and consequently these have sometimes been conjugated with other antigens in an attempt to improve the immunological response.

Polysaccharide vaccines

Meningococcal

Pneumococcal

H.influenzae type b.

Toxoid vaccines

These are toxins, which have been rendered non-toxic by treatment with formaldehyde, but their antigenicity is maintained.

Toxoid vaccines

Diphtheria toxoids

Tetanus toxoids

Genetically engineered vaccines

Hepatitis B

Vaccination Schedule

The followings are the common infectious diseases against which world health organization(WHO) recommends routine immunization.

Tuberculosis

Diphtheria

Pertusis

Tetanus

Polio

Measles

Hepatitis B.

Expanded Programme on Immunization (EPI)

Expanded Programme on Immunization (EPI)

Vaccination Schedule
Pregnant women

Pregnant women(pregnancy 4th-8th mo)

TT1 & TT2 at one moth interval(1st pregnancy)

TT one dose (subsequent pregnancy; if within 5 yr)

TT two doses (subsequent pregnancy; if beyond 5 yr)

Vaccination Schedule
General women

General women(age 15-49)

TT-1  at any age

TT-2 after one month

TT-3 after 6 month

TT-4 after 1yr

TT-5 after 5 yr

Precautions and recommendations

Live vaccines should not be administered to children with immuno-deficiency disease.

Injection should be given into the lateral thigh or into the deltoid.

Deep injection and massage reduces the incidence of antigenic cysts.

DPT injection may cause mild fever within 12-24 hours and it is not a contraindication for further immunization.

Precautions and recommendations

If convulsions occur within 72 hours of DPT injection further administration of pertussis vaccine is contra-indicated. Then give DT alone

After 2 years of age children should not receive pertussis vaccine.

Children with brain damage or previous history of convulsion should not receive pertussis vaccine.

In case of high risk due to contact with a case of pertussis, DPT can be initiated at 2 week of age.

In the event of an epidemic or high risk, measles vaccine can be given at 6 months age.

Precautions and recommendations

Immunization should be delayed only in case of illness with high fever, so that any sign of the illness will not attributed to the vaccination.

Administration of a live attenuated vaccines should be delayed for at least six weeks when a recent injection of polyvalent immune globulin has been given.

Conditions, which are not contra-indicated to immunization

Minor illness such as upper respiratory tract infections or diarrhea,with fever < 38.5º C.

Allergy ,asthma, or other atopic manifestations.

Prematurity, small for date infants.

Malnutrition

Family history of convulsions

Treatment with antibiotics, low dose corticosteroids or locally acting steroids.

Conditions, which are not contra-indicated to immunization

Dermatitis ,eczema, or localized skin infections.

Chronic diseases of the heart ,lung, kidney and liver.

Stable neurological conditions such as  cerebral palsy and Down syndrome.

History of jaundice after birth.

BCG vaccine

Bacille Calmette Guerin(BCG) is the most widely used vaccine

BCG is made of a live, weakened (attenuated)strain of mycobacterium bovis

Ideal age for vaccination is the newborn period(1st week) if not given at birth then at 6 weeks

It is effective in reducing the likelihood and severity of TB in infants and young children.

Vaccine dose

It is given intra-dermally in a dose of 0.05 ml for newborns and 0.1 ml for all other children

Vaccine Efficacy

0-80% for TB lung

75-86% for meningitis and miliary tuberculosis.

Duration of immunity unknown but some evidence that duration 10-15 yrs.

Course of BCG

The wheal of injection disappears in 30 minutes

Two to three weeks later a nodule forms which indurate and forms a superficial abscess, it ulcerates and heals in 4-6 weeks.

The whole process is completed in 2 months and leaves a scar.

Complications of BCG

Koch’s phenomenon i.e., accelerated reaction which completes in about 10 days

Erythema nodosum

Deep abscess and ulceration

Lymphadenopathy of supra- clavicular or axillary nodes

Generalized tuberculosis.

Poliomyelitis vaccine

Vaccine available against poliomyelitis are:

Live attenuated oral poliovirus vaccine(OPV, Sabin)[Contain attenuated poliovirus I,II and III]

Injectable poliovirus vaccine( IPV, Salk)

Vaccine Efficacy

>90% in industrialized countries

72-98 % in hot climates

Lower protection against type 3

Life long immunity after booster dose

Advantage of OPV

It is easy to administer

It has superior antibody response

Provides rapid immunity within 1 week

Provides herd immunity

Side effect of OPV

Paralytic polio in immunized child(1:6 million)

Contra-indication of OPV

Infection with HIV

Known immune deficiency

Tetanus immunization

Active immunization

Passive immunization

Active immunization

Active immunization:Tetanus toxoid

Tetanus toxoid(TT) is prepared by inactivating the toxin with formaldehyde.

Newborns can be protected from tetanus if mother is actively immunized during pregnancy

Dose of toxoid

Vaccine is administered intra-muscularly in a dose of 0.5 ml

Two 0.5ml dose I/M at 4-8 weeks interval

Third dose after 1 yr

Booster dose after 5-10 yrs

Passive immunization

Passive immunization:Tetanus immunoglobulin(TIG)

It is used for prophylaxis and therapy

Provides protection for 30 days

Prophylactic dose is 250 IU I/M

Therapeutic dose is 1000-10000 IU ,I/M

Tetanus antitoxin(ATS)

Tetanus antitoxin(ATS)

Protection last for 7-15 days

Prophylactic dose is 1500-3000 IU,I/M

Therapeutic dose in neonates 10000 I/M

Therapeutic dose in children 40000-60000 IU(half I/M, half I/V)

Hepatitis B vaccine

Routine  vaccination is given to all infants, children and adolescents

Hepatitis B vaccine Dose

Dose of vaccine is 0.5 ml if age is less than 19 yrs Dose is 1 ml if age is more than 19 yrs

Optimally, three I/M doses of hepatitis B vaccine are needed, schedule ,0,1,and 6moths.

Hepatitis B vaccine should be given only in the deltoid muscle for adolescents and children, and in the antero -lateral thigh muscle for infants and neonants

HEPATITIS B VACCINE

Infant born to HBsAg positive mothers:

Infant born to HBsAg positive mothers should receive 0.5 ml of hepatitis B immune globulin(HBIG) within 12 hours after birth, and hepatitis B vaccine at a separate site.

The second dose of vaccine is recommended at age 1-2 months and third dose at age 6 month.

At 12-15 months of age immunized infants should be tested for antibody to HBsAg(ant-HBs),if anti-HBs is positive, vaccination has been effective.

If negative immunization has failed and the infant is a chronic carrier.

Haemophilius influenzae type b vaccine

  1. influenzae type b (Hib) is a common cause of bacterial meningitis and variety of serious and potentially life threatening infectious, including pneumonia, epiglottitis and sepsis in infants and older children

It is adapted to the routine schedule and given together with DPT,as well as a booster dose at 18 months.

Older children and adults require only 1 dose.

Others

Pneumococcal vaccines

Typhoid vaccine

Cholera vaccine

Rabies immunization

Pneumococcal vaccines

Streptococcus pneumoniae is responsible for three types of diseases, pneumonia, otitis and meningitis.

It is the leading cause of severe pneumonia in children under 5 years age.

The current vaccine against S. pneumoniae is composed of capsular antigen to 7,9 or 23 serotypes.(dose 0.5ml IM or SC)

Recommendations are to a give dose of vaccine to children over 2 years of old who are high risk(sickle cell disease, chronic renal failure, immunosupression from organ transplantation and HIV infection)

The vaccine is of limited efficacy in children under 2 years of age.

Typhoid vaccine

In most endemic areas the incidence of typhoid fever is highest in children 5-19 years of age; hence a vaccine is needed that can establish durable immunity prior to school age.

Purified Vi antigen is used  as a one dose injectable vaccine

The dose of Vi is a single intramuscular dose(0.5ml)with booster needed every 2 years.

Its protective efficacy ranges from 17-66 %.

Cholera vaccine

Cholera vaccine provides only partial protection (50%) of short duration(3-6 months) and use not regarded as a useful public health intervention.

Furthermore, it confers no protection against serotype 0139, the currently circulating strain of vibrio cholerae.

The vaccine may be administered SC or IM.

A primary series consists two doses at least 1 week apart.

Booster may need to given as frequently as every 6 month.

Rabies immunization

Active immunization: Human diploid cell vaccination(HDCV).

Pre-exposure prophylaxis:

Dose is 1 ml by SC or IM injection.

2 doses are given at intervals of four weeks

Then booster dose after 1 year.

Thereafter booster dose 3-4 yearly if needed.

Post-exposure prophylaxis:

Dose 1 ml by SC or IM injection

4 doses on days 0,3,7,14 and 28.

Rabies immunization

Passive immunization:

Human rabies immunoglobulin:

Human rabies immunoglobulin used if HDCV is not available.

It should be given in a dose of 20 IU/Kg, IM; half of these dose is infiltrated at wound site.

Rabies antiserum:

For passive immunization when human anti-rabies immunoglobulin is not available.

Dose is 40 IU/Kg body weight by IM injection. Part of it is infiltrated around the wound.

 

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