Last Updated : 1/9/2014
Nitin Shah

What is vaccination or immunization?

A. 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).In few states, Hib vaccine (against H.influenza B) and MMR vaccine (against measles, mumps and rubella) have been introduced.
The time schedule of giving these vaccines is shown in the table I.

Table 1: EPI schedules as recommended by Govt. of India
Birth -15 days- BCG + OPV (ZERO DOSE)
6 weeks - OPV1 + DPwT1 + Hep B1 + Hib 1*
10 weeks - OPV2 + DPwT2 + Hep B2+ Hib 2*
14 weeks - OPV3 + DPwT3 + Hep B3+ Hib 2*
9 months - Measles Vaccine
15 months-18 months - 1st booster of OPV/ DPwT + MMR*
5 years -6 years - 2nd booster of DPwT
10 years - Tetanus Toxoid
16 years - Tetanus Toxoid

* These vaccines have been introduced in few states currently, Hep B = Hepatitis B vaccine

Vaccination schedule recommended by Indian Academy of Pediatrics (IAP) 2013

Table 2- IAP Time Schedule of routine vaccination

Birth - 15 days

BCG + OPV (zero dose) +HepB1

6 weeks - 8 weeks

OPV1 +IPV1 + DPT1* + HepB2 + Hib1 + Rotavirus1 + PCV1

10 weeks- 12 weeks

OPV2 + IPV2 + DPT2* + Hib2 + Rotavirus2 + PCV2

14 weeks - 16 weeks

OPV3 + IPV3 + DPT3* + Hib3 + Rotavirus3# + PCV3

6 months

HepB3 + OPV1

9 months (completed)

Measles vaccine + OPV2

12 months

Hepatitis A1

15 months

MMR1 + Varicella + PCV booster

18 months

OPV4 + IPV booster1 + DPT*booster1 + Hib booster1 + Hepatitis A2

2 years

Typhoid1 (give repeat shots every 3 years)

5 years

OPV5 + DPT* booster2 +MMR2^ + Varicella2$$

10 - 12 years

Tdap/Td (Every 10 years then give Td)+ HPV**

*DPT: It is given either as DPaT or DPwT
**HPV is given only in females (3 doses at 0,1-2 months and 6 months interval)
#Rotavirus 3rd dose may be required only with one brand)
^ MMR 2nd dose can be given at any time 4-8 weeks after the first dose
$$ Varicella 2nd dose can be given anytime 3 months from the first dose
PCV= Pneumococcal conjugated vaccine, IPV= Injectable polio vaccine, Td = Tetanus toxoid + adult dose of pertussis toxoid, HPV= Human papillomavirus

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.


Contributor Information and Disclosures

Nitin Shah
Consultant Pediatrician, B J Wadia Hospital for Children, Hinduja Hospital, Mumbai, India

First Created : 1/9/2001

