Introduction

Immunization is the process of artificially inducing immunity or providing protection from disease. It is achieved by the administration of vaccines which are agents that induce an active immune response in the host.

Importance of immunization

The main purpose of the immune system is to identify and eliminate foreign substances, called antigens, from the body. The immune system defends the body against antigens by making proteins called antibodies, which help eliminate antigens. This system is also involved in inactivated viruses, microbes, and bacteria, as well as remembering prior interactions (immunologic memory) with these agents to mount a stronger response upon next exposure.

Types of vaccines

There are two types of vaccines:

1. Live attenuated: These vaccines are produced by modifying a bacterium or virus so it can replicate and produce immunity without causing disease.
2. Inactivated vaccines: They are made of bacteria or viruses that are modified or killed with heat or chemicals. These microbes are not alive, nor can they replicate or cause disease in the recipient.

A childhood and adolescent immunization schedule for vaccine and age has been recommended for routine administration of currently licensed childhood vaccines for the children from birth through the age 18 years. This schedule provides for protection against 13 diseases through the administration of 10 different vaccines.

Immunization schedule

(Indian Academy of Paediatrics, Committee on Immunization, 2006) (Advisory Committee on Immunization Practices - ACIP, Centre for Disease Control and Prevention, United States, 2008)

Immunization schedule for adolescents

Immunization recommendations in HIV-infected children

(Lancet Infect Dis 2004, 4:510-18)

* (OPV: Oral Polio Vaccine, BCG: Bacillus Calmette Guerine, DPT: Diphtheria-Pertussis-Tetanus Vaccine, DT: Diphtheria-Tetanus Vaccine, TT: Tetanus toxoid, MMR: Measles-Mumps-Rubella, HBV: Hepatitis B vaccine, HiB: Haemophilus influenza B, IPV: Inactivated Polio Vaccine)

BCG vaccine: Protects against tuberculosis, mainly severe form of tuberculosis

Polio vaccine: Protects against poliomyelitis, a dreaded childhood disease leading to permanent weakness or paralysis of legs, arms or both, which can lead to permanent disability and even death.

Hepatitis B vaccine: Protects against contagious liver disease that result from hepatitis B virus. Disease can cause lifelong infection, liver failure and even death. Hepatitis B virus spread through blood and body fluid.

Hepatitis A vaccine: Protects against contagious liver disease that result from hepatitis A virus. Disease can cause liver infection resulting in jaundice. Other symptoms are vomiting ,loss of appetite and abdominal pain. In some children it can lead to liver failure and even death. Hepatitis A virus spread through contaminated food and water.

Oral Rotavirus vaccine: Protects against rotavirus, the most common cause of severe diarrhoea and dehydration in infants.

DTP vaccine: Protects against Diphtheria, pertussis and tetanus.

HiB vaccine: Protects against meningitis (an infection of the covering of brain and spinal cord), pneumonia (lung infection), epiglottitis( a severe throat infection) and other infect.

Pneumococcal vaccine: Protects against pneumonia and meningitis. Young children (younger than 5 years) have highest incidence of serious diseases.

Influenza (flu) vaccine: Protects against contagious respiratory illness caused by Influenza virus. It can cause mild to severe illness.

Measles vaccine: Protects against highly contagious and serious illness. It spread by droplets or direct contact with nasal or throat secretions of infected person.

MMR vaccine: Protects against 3 common childhood disease namely Measles, Mumps and Rubella (German measles). Mumps causes fever, muscle ache and loss of appetite; followed by inflammation of salivary glands. In some children complications such as inflammation of brain and/or covering of brain and spinal cord (encephalitis/meningitis), inflammation of testicles (orchitis) inflammation of ovaries (oophoritis) deafness (usually permanent) may be seen.

Chickenpox vaccine: Protects against diseases caused by exposure to the varicella zoster virus. A skin rash with blister covering the body but usually more concentrated on face, scalp and trunk. Almost everyone suffer from infection once n a life.

Typhoid vaccine: Protects against typhoid fever, a life threatening illness caused by bacterium salmonella typhi.

Cervical cancer (HPV) vaccine: Protects against cervical cancer, the most common cancer amongst all Indian women.

Note:

1. If mother is Hepatitis B negative – HBV at 6,10,14 weeks
2. If mother’s Hepatitis B status unknown – start vaccination soon after birth to prevent perinatal transmission of the disease.
3. If mother is Hepatitis B positive – Hepatitis B Immunoglobulin (HBIG) within 24 hours of birth along with HBV.
4. Rotavirus Vaccine (Rota) – Dose 1 at 6-12 weeks, consequent two doses at 2 month intervals. Complete three doses should be administered between age 12-32 weeks.
5. A vaccine series does not require restarting, regardless of the time that has elapsed between doses.
6. Live-virus or live-bacteria vaccines (OPV, MMR, BCG, Typhoid vaccine) should not be administered in children who are immunocompromised (e.g. cancer or corticosteroid therapy) or allergic to specific vaccinations.

Immunization of children has had the most profound impact in decreasing diseases and represents the most efficacious and cost-effective way to prevent disease and therefore, the parents should strive to follow the immunization schedule for the child as per the recommended time intervals for administration of vaccines.

References

1. Current Pediatric Therapy, Eighteenth Edition. Fredric D. Burg, Julie R. Ingelfinger, Richard A. Polin, Anne A. Gershon. Elsevier Inc. ISBN-13: 978-0-7216-0549-4.
2. Current Diagnosis & Treatment: Pediatrics, Nineteenth Edition. William W. Hay, Jr.,Myron J. Levin, Judith M. Sondheimer,Robin R. Deterding. The McGraw-Hill Companies, Inc. ISBN 978-0-07-154433-7.
3. Manual of Clinical Problems in Pediatrics, Fifth Edition. Kenneth B. Roberts, Lippincott Williams & Wilkins
4. Manual of Neonatal Care, Sixth Edition. John P. Cloherty, Eric C. Eichenwald, Ann R. Stark, Lippincott Williams & Wilkins.
5. Textbook of Pedodontics, Second Edition. Shobha Tandon, Paras Medical Publisher, ISBN 978-81-8191-241-1.