IMMUNIZATION OR VACCINATION

What is vaccination or immunization?
Vaccination or immunization are terms used interchangeably. Both the terms mean process of giving vaccines or ‘shots’ to children or adults so that they develop immunity or resistance against that particular disease.

How does a vaccine work?
Normally in many diseases the disease-forming germ enters the body, produces the disease & subsequently the body mounts immune response or fighting power against the germ and lastly one recovers from the disease. Here immunity against disease is produced after one has suffered from the disease. A vaccine is nothing else but whole or part of the disease germ, which has been processed or modified in such a way than it has lost its capacity to produce disease but it can still induce immunity or fighting power by body when administered in the body. Hence by vaccination one develops immunity without suffering from the disease.

What are the types of vaccine?
One can look at the types of vaccines from different angles. Different vaccines work against different diseases like there are separate vaccines for poliomyelitis, measles, diphtheria, tetanus etc. Vaccines can be oral vaccines like oral polio vaccine or oral typhoid vaccine or it can be injectable vaccine like DPT vaccine or hepatitis B vaccine. Vaccines can be single vaccine like the measles vaccine or combination of more than one vaccine like the MMR vaccine (which acts against meals, mumps & rubella) or the DPT vaccine (which acts against diphtheria, pertussis & tetanus). Injectable vaccines can be given subcutaneously i.e. below the skin like the measles vaccine or given intramuscularly i.e. in the muscle like DPT vaccine. Lastly vaccines are usually given prophylactically i.e. before the exposure to the disease germs like most of the vaccines e.g. polio vaccine, DPT, vaccine etc. Some vaccines work when given even after the exposure to the disease germ like the rabies vaccine, which is given after the dog bite. Hence one can look at the various vaccines from different angles.

Which vaccines are usually given to a baby?
The vaccines recommended routinely to a baby differ from authority to authority. We will mainly discuss the schedule recommended by Govt. of India & that recommended by Indian Academy of Pediatrics

Govt. of India schedule:

The minimum vaccines that an Indian child should receive are the vaccines recommended by Govt. of India under the Expanded programme of Immunization (EPI). It includes 3 doses of tetanus toxoid given to the mother during the pregnancy to protect both the mother and the newborn from tetanus.

After birth the baby receives vaccines against seven killer vaccine preventable diseases including BCG (against tuberculosis) oral polio vaccine (against poliomyelitis), DPT vaccine (against Diphtheria, Pertussis, Tetanus), hepatitis B (against Hepatitis B) & measles vaccine (against measles).
The time schedule of giving these vaccines is shown in the table I. Individual vaccines are discussed somewhere else.

Table I: EPI schedules as recommended by Govt. of India.

Birth -15 days - BCG + OPV (ZERO DOSE) + Hep B1 6 weeks -8 weeks -OPV1 + DPT1 + Hep B2 10 weeks - 12 weeks - OPV2 + DPT2 14 weeks - 16 weeks - OPV3 + DPT3 6 months - Hep B3 9 months (completed) - Measles vaccine 15 months-18 months - 1st booster of OPV/ DPT 4 years -6 years - DT vaccine 10 years -Tetanus Toxoid 16 years -Tetanus Toxoid

Vaccination schedule recommended by Indian Academy of Pediatrics (IAP):
Table II- IAP Time Schedule of routine vaccination

Birth – 15 days BCG + OPV (zero dose)Hepatitis B 1st Dose 6 weeks – 8 weeks OPV1 + DPT1Hepatitis B 2nd dose + Hib 1st dose 10 weeks – 12 weeks OPV2 + DPT2 + Hib 2nd dose 14 weeks – 16 weeks OPV3 + DPT3 + Hepatitis B 3rd dose + Hib 3rd dose 9 months (completed) Measles vaccine 15 – 18 months 1st Booster dose of OPV + DPT + Hib+MMR vaccine 4 – 6 years 2nd booster dose of OPV + DPT 10 years Tetanus toxoid 16 years Tetanus toxoid

Are there some more vaccines given by doctors?
These include typhoid vaccine & Hib vaccine. These are costly vaccines. But for the cost, they are recommended as routine vaccines for all children. The currently available typhoid vaccines given are after 2 years of age & repeated every 3-5 years there after. Common childhood diseases like hepatitis A & chicken pox lead to more suffering but very less chance of death. These diseases are usually mild & self-limiting in children & hence option of routine vaccination of children is left to parents. This makes their use optional as per wishes of parents. Chickenpox and Hepatitis A vaccine can be given after 1 year of age..

Can a vaccine be given when a child is sick?
Minor illness like mild cough, cold, loose stools, vomiting or even mild fever is not a contraindication for vaccination. However if a child is suffering from severe diseases, high fever, severe loose stools, pneumonia or any other illness needing investigation or admission to a hospital, vaccination should be postponed till full recovery. OPV dose can be given during diarrhea but should not be counted & an extra dose in the schedule should be given.

What precautions should one take before vaccination?
Foremost is to complete the schedule in time. Do tell the doctor about any adverse effects seen to previous immunization. Understand properly the implications of giving or not giving the vaccine under optional category. One can feed the child including breast feeds before & after any vaccination.
There is no need to starve the child before vaccination. Maintain properly the vaccination card & take it along during each vaccination for the doctor to see record.

What precautions should be taken after vaccination?
Keep firm pressure for few minutes at the injection site with a spirit swab. Do not massage or rub at the injection site. Wait in the consulting room for another 30 minutes should any reaction develop following vaccination. Note down carefully when to come back for next vaccination. Inform the doctor immediately if the child develops any reaction or abnormal behavior or habits following vaccination in the next few days.

What are the common side effects of vaccination?
Most of the vaccines are very safe. Patient can get pain, redness, swelling at the injection site. It is less common with subcutaneous injections. Rarely a nodule may form which remains for few weeks especially following DPT. Patient can develop mild to moderate fever, which usually responds to paracetamol. Never give aspirin for pain or fever following vaccination especially after varicella vaccine.
Rarely child can develop fussiness, irritability, anorexia, vomiting, diarrhea, excessive crying etc. especially after DTP injection. Lastly there could develop severe reaction like convulsion, depressed responsiveness, altered consciousness, shock, hyperpyrexia (fever>1050C) with DPT, which must be reported immediately to the doctor.
Not all the vaccines lead to reactions. Not all the children develop reaction nor does it develop with each dose of vaccine. Equally important is the fact that development of some reaction like fever or pain is not a prerequisite of good action of vaccine.

What are contraindications to vaccination?
Patients with severe reactions to previous immunization should not receive same vaccine again. Patients will severe egg allergies should not be given measles or MMR vaccine. Patients with immune compromised state like symptomatic HIV or AIDS should by and large not receive live vaccines especially if a killed vaccine substitute is available. Of course there are some exceptions to this rule & for details refer to individual vaccines.

What should be minimum gap between 2 vaccines?
As discussed before, any number of vaccines can be given on same day at separate sites but if not given on same day there should be gap of 4 weeks between two vaccines in general. One should not give one vaccine today, second 7 day & 3rd vaccine after another 7 days. Extra doses of OPV like in pulse immunization or ring immunization is notable exemption to this rule. Some vaccines like rabies vaccine have schedule where 5 doses are given in 1 month’s time. Again rabies vaccine or tetanus toxoid when indicated should be started as soon as possible irrespective of vaccines received in recent past

 

Last updated on 02-12-2003