Immunization | Medical Science Optional Notes for UPSC PDF Download

Introduction

• Immunization is the method by which an individual is rendered immune or resistant to an infectious disease, usually through the application of a vaccine.
• Vaccines work by activating the body's natural immune system to defend against future infections or diseases.
• A vaccine typically contains one or more antigens from a harmful agent. When given to someone who has not been previously exposed, it triggers an immune response without causing illness.
• Strengthening immunization coverage is a crucial element of the NRH (presumably National Immunization Program or similar).

National Immunization Schedule

Expanded program of Immunization

• In 1974, the World Health Organization (WHO) initiated the Expanded Program of Immunization (EPI) with the primary goal of reducing morbidity and mortality caused by six common preventable childhood diseases: tuberculosis, diphtheria, pertussis, tetanus, poliomyelitis, and measles.
• The term "Expanded" in the WHO's definition implied the addition of more disease-controlling antigens to vaccination schedules, expanding coverage nationwide, and extending services to reach underprivileged sectors of society. In 1978, India introduced EPI, initially focusing on urban areas post the eradication of smallpox.
• Throughout the program's inception, UNICEF has played a crucial role by providing substantial support to EPI.
• Although the WHO refers to its program as EPI, UNICEF, in 1985, renamed it "Universal Child Immunization" (UCI). Despite the different names, there is no distinction between the two, as both aimed to achieve universal immunization by 1990.
• The program comprises two essential components: immunization of pregnant women against tetanus and immunization of infants during their first year against the six EPI target diseases.
• The goal set was to attain 100% coverage of pregnant women with two doses of tetanus toxoid (or a booster dose) and, by 1990, achieve at least 85% coverage of infants with three doses each of DPT, OPV, one dose of BCG, and one dose of measles vaccine.

Cold Chain

The cold chain is a logistical system designed for the transportation and storage of vaccines, ensuring they are maintained at the recommended temperature from the manufacturing facility to the point where they are administered.

Cold chain equipment's

Vaccine vial monitoring

• A vaccine vial monitor (VVM) is a temperature-sensitive label affixed to vaccine vials, providing a visual indication of the vaccine's potency preservation.
• The VVM comprises a heat-sensitive square within a circle.
• Exposure to heat causes the monitor to change color, and this color change accelerates with rising temperatures.
• If the square matches the circle's color or becomes darker, it signals potential damage to the vaccine, and the vial should be discarded.
• Presently, there are four types of VVMs (VVM2, WM7, WM14, and VVM30), chosen to align with the specific heat sensitivity of the respective vaccines.

Open vial policy

• An Open Vial Policy is essential to ensure the effectiveness of vaccines while minimizing wastage by appropriately managing opened vials.
• Opened vials, when handled correctly, can be utilized to extract several doses.
• Included vaccines in multi-dose vials are OPV, DTP, TT, DT, Hepatitis B, and liquid formulations of Hib vaccine.
• Opened vaccines can be used for up to 28 days in subsequent immunization sessions, given the following conditions:
  a) The expiry date remains valid.
  b) The vaccines are stored under proper cold chain conditions.
  c) Aseptic technique is employed for withdrawing all doses.
  d) The vaccine vial monitor (VVM), if attached, has not reached the discard point.
• Open vials of Measles, BCG, and Japanese Encephalitis must be discarded after each immunization session and should not be kept for more than 6 hours. (These vaccines are freeze-dried formulations and lack preservatives.)

MMR Vaccine

Hib Vaccine

Pneumococcal Vaccine

Immunization-Repeats

Q1: Outline the National Immunization Schedule as practiced under the RCH programme. (2010)

Q2: Write short notes on (i) Cold chain (ii) Measles, Mumps, and Rubella Vaccine. (2011)

Q3: Tabulate the National Immunization Schedule. What are newer vaccines? Give their immunization schedule. (2012) 

Q4: What do you understand by Expanded Programme of Immunization (EPI)? Describe its components. (2013)

Q5: Describe the characteristics of Haemophilus infuenzae b (Hib) vaccine. Enumerate the diseases which can be prevented by this vaccine. Describe the primary schedule of vaccination with Hib vaccine in an 8-month-old child. (2014)

Q6: Enlist the vaccines which can reduce the incidence of Acute Respiratory Infection in children. (2017)