Enumerate the various types of vaccines available in National Immunization Schedule (NIS) in children. Define adverse events following immunization. State the adverse events of any three vaccines.

Various Types of Vaccines Available in National Immunization Schedule (NIS) in Children (India, as of 2024)

The National Immunization Schedule (NIS) in India outlines the specific vaccines, dosages, routes, and sites of administration for children from birth up to 16 years, ensuring comprehensive protection. The schedule is regularly updated based on epidemiological data and global recommendations.

• At Birth:
  • BCG (Bacillus Calmette-Guérin): Protects against severe forms of Tuberculosis.
  • Hepatitis B (Birth Dose): Prevents Hepatitis B infection.
  • OPV-0 (Oral Polio Vaccine): Provides initial protection against Polio.
• At 6 Weeks:
  • OPV-1: Oral Polio Vaccine.
  • Pentavalent-1: A combination vaccine protecting against Diphtheria, Pertussis (Whooping Cough), Tetanus, Hepatitis B, and *Haemophilus influenzae* type b (Hib).
  • Rotavirus Vaccine (RVV)-1: Protects against severe rotavirus diarrhea.
  • fIPV-1 (Fractional Inactivated Polio Vaccine): Administered intradermally.
  • PCV-1 (Pneumococcal Conjugate Vaccine)*: Protects against pneumococcal diseases (introduced in selected states/districts).
• At 10 Weeks:
  • OPV-2: Oral Polio Vaccine.
  • Pentavalent-2: Second dose of the combination vaccine.
  • RVV-2: Second dose of Rotavirus Vaccine.
• At 14 Weeks:
  • OPV-3: Oral Polio Vaccine.
  • Pentavalent-3: Third dose of the combination vaccine.
  • fIPV-2: Second fractional dose of Inactivated Polio Vaccine.
  • RVV-3: Third dose of Rotavirus Vaccine.
  • PCV-2 (Pneumococcal Conjugate Vaccine)*: Second dose for selected states/districts.
• At 9-12 Months:
  • Measles & Rubella (MR)-1: Protects against Measles and Rubella.
  • JE-1 (Japanese Encephalitis)*: Administered only in endemic districts.
  • PCV Booster*: Booster dose for Pneumococcal Conjugate Vaccine in selected states/districts.
  • Vitamin A (1st dose): Supplementation.
• At 16-24 Months:
  • MR-2: Second dose of Measles & Rubella vaccine.
  • JE-2 (Japanese Encephalitis)**: Second dose in endemic districts only.
  • DPT Booster-1 (Diphtheria, Pertussis & Tetanus): First booster dose.
  • OPV Booster: Booster dose of Oral Polio Vaccine.
  • Vitamin A (2nd to 9th dose): Subsequent doses every 6 months up to 5 years.
• At 5-6 Years:
  • DPT Booster-2: Second booster dose.
• At 10 Years & 16 Years:
  • Td (Tetanus and adult Diphtheria): For adolescents.

*Note: PCV and JE are included in selected states/districts as per specific guidelines.

Definition of Adverse Events Following Immunization (AEFI)

An Adverse Event Following Immunization (AEFI) is defined as any untoward medical occurrence which follows immunization and which does not necessarily have a causal relationship with the usage of the vaccine. The adverse event may be any unfavorable or unintended sign, an abnormal laboratory finding, a symptom, or a disease. AEFIs can range from mild local reactions to severe, life-threatening conditions, or even coincidental events unrelated to the vaccine. Accurate reporting and investigation of AEFIs are crucial for maintaining public confidence in vaccination programs and ensuring vaccine safety surveillance.

Adverse Events of Three Vaccines

1. Diphtheria, Pertussis, and Tetanus (DPT/Pentavalent) Vaccine

The DPT vaccine (or its component within the Pentavalent vaccine) protects against three serious bacterial diseases. While highly effective, it can cause various adverse events:

• Common and Mild:
  • Local Reactions: Pain, redness, swelling, and tenderness at the injection site. These usually occur within 1-3 days.
  • Systemic Reactions: Mild fever (up to 1 in 4 children), fussiness, irritability, tiredness, loss of appetite, and sometimes vomiting or diarrhea. These often appear within 24-48 hours.
• Less Common but More Severe:
  • High Fever: Temperatures of 105°F (40.5°C) or higher.
  • Persistent, Inconsolable Crying: Lasting for three hours or more.
  • Febrile Seizures: Seizures associated with fever. These usually occur within one week after the shot.
  • Hypotonic-Hyporesponsive Episodes (HHE): A sudden onset of pallor, limpness, and reduced responsiveness.
  • Swelling of the entire arm or leg: Where the shot was given, typically lasting 1-7 days, more common after booster doses.
• Very Rare and Serious:
  • Severe Allergic Reactions (Anaphylaxis): Life-threatening reactions requiring immediate medical attention, occurring within minutes to a few hours.
  • Long-term Seizures, Coma, or Permanent Brain Damage: These are extremely rare, and a causal link is often difficult to establish definitively.

2. Measles and Rubella (MR) Vaccine

The MR vaccine (often combined as MMR with Mumps) protects against measles and rubella, two highly contagious viral diseases. Adverse events are generally mild:

• Common and Mild:
  • Local Reactions: Pain, redness, and soreness at the injection site.
  • Fever: A mild fever is common, often appearing 7-11 days after vaccination.
  • Mild Rash: A raised, blotchy rash, similar to a mild measles rash, can appear 7-11 days post-vaccination. This is not infectious.
  • Swollen Glands: Around the cheeks, neck, or jaw, mimicking mild mumps, can occur 2-3 weeks after vaccination.
  • Joint Stiffness/Pain: More commonly reported in adult women, but can occur in adolescents.
• Less Common but More Serious:
  • Febrile Seizures: A small increased risk, particularly in children younger than 7 years, typically occurring 8-14 days after vaccination (approx. 1 in 3,000-4,000 children). These are usually not associated with long-term effects.
  • Temporary Pain and Stiffness in Joints: Primarily in teenage or adult women who did not already have immunity to the rubella component.
• Very Rare and Serious:
  • Severe Allergic Reactions (Anaphylaxis): Extremely rare but possible.
  • Thrombocytopenic Purpura: Red or purple discolorations on the skin due to low platelet count, very rare.

3. Oral Polio Vaccine (OPV)

The Oral Polio Vaccine (OPV) is a live, attenuated vaccine administered orally to protect against polio. It has been instrumental in global polio eradication efforts, but has specific rare adverse events:

• Common and Mild:
  • OPV is generally well-tolerated with very few mild adverse events directly attributed to the vaccine. General symptoms like headache, belly pain, mild fever, and diarrhea can occur, but these are often coincidental.
• Rare and Serious:
  • Vaccine-Associated Paralytic Poliomyelitis (VAPP): This is the most significant adverse event associated with OPV. The weakened live virus in the vaccine can, in very rare instances (approximately 1 case per 2.7 million doses administered), revert to a virulent form and cause paralysis in the vaccinated individual or their close contacts (vaccine-derived poliovirus, VDPV). The risk is higher for the first dose and in immunocompromised individuals.
  • Circulating Vaccine-Derived Poliovirus (cVDPV) Outbreaks: In areas with low vaccination coverage, vaccine-derived polioviruses can circulate and potentially cause outbreaks, leading to paralysis. This is a public health concern rather than an individual adverse event in the vaccinated child, but it stems from the properties of the live vaccine.
  • Aseptic Meningitis and Encephalitis: On rare occasions, particularly in immunodeficient infants, these neurological complications have been reported following OPV.

It's important to note that due to the risk of VAPP and cVDPV, many countries, including some in the NIS, are transitioning towards or incorporating Inactivated Polio Vaccine (IPV) more prominently into their schedules.