Vaccines & Cold Chain

Vaccines are an essential component of preventive medicine, which is a critical part of public health. Knowledge of vaccines and their management is crucial for preventing the spread of infectious diseases and reducing the incidence of vaccine-preventable diseases.

In this blog, we’ll discuss vaccines and their classification, contraindications, AEFIS, cold chain, switch program and more. Keep reading.

Classification Of Vaccines

Live	Killed	Toxoids	Combined
BCG OPV MMR Typhoral JE live Epidemic Typhus YF VZ Rotavirus	Rabies IPV Hep A	Diphtheria Tetanus	DPT MMR MR Td
Proteinaceous Pertussis Anthrax	Polysaccharide & Glycoconjugate Meningococcal HiB Pneumococcal	Recombinant Hep B HPV

NIS (National Immunization Schedule, India 2020-21)

• At Birth: BCG, OPV, Hep B
• 6 W: DPT₁, OPV₁, Hep B₁, HiB₁, Rota V₁, fIPV₁, PCV₁
• 10 W: DPT₂, OPV₂, Hep B₂, HiB₂, Rota V₂
• 14 W: DPT₃, OPV₃, Hep B₃, Rota V₃, fIPV₂, PCV₂, HIB₃
• 9 M: Measles₁/MR₁, Vitamin A (1 Lac IU), PCV_booster, JE_1Live
• Every 6 months: Vitamin A (2 Lacs IU) till 5 years
• 16–24 months: DPT_booster, OPV_booster, Measles₂/MR₂, JE_2Live
• 5 Years: DPT_booster
• 10 Years: TT
• 16 Years: TT
• Pregnancy: TT
• TT: Replaced with Td(tetanus diphtheria combination vaccine)
• Total Vit A given under NIS is 17 Lac IU

Contraindications

• Pregnancy: All live vaccines are C/I as it is an immuno-compromised state except yellow fever.
• Lactation: All vaccines are safe except yellow fever
• HIV: All live vaccines C/I 
• Symptomatic HIV+: All vaccines are C/I except MMR, Varicella, Zoster
• Asymptomatic HIV+: No C/I.
• Similarly, in a newborn infant, all live vaccines are contraindicated if the newborn is HIV positive except OPV & measles vaccine. BCG vaccine use is controversial in HIV +ve newborns. Ideally, it should not be given. 
• Prematurity &< 2 kg BW is a contraindication for Hepatitis B vaccine
• Epilepsy: C/I Pertussis.
• Cerebral Palsy: No C/I, as it is a non-progressive disease.

AEFIS (Adverse Events Following Immunization)

• Ideal recommended observation time after immunization of a child is 30 minutes. 
• Paralysis: OPV, paralysis is of 2 types 
  • VAPP (P₃) 
  • VDPV (cP₂)
• Hypersensitivity reaction & shock: Hep B
• TSS: Measles
• GBS: Killed Influenza/ Swine flu vaccine
• Intussusception: Rota V
• Febrile seizures: Measles
• Persistent crying & HHE (Hypotensive, Hypo-responsive episode): Pertussis
• Thrombocytopenia: MMR, Hep B

Lyophilized Vaccines/ Freeze Dried Vaccines

• They are in powdered form
• BCG: Reconstituted with normal saline 
• YF: Reconstituted with cold physiological saline
• JE: Reconstituted with phosphate buffer saline (PBS)
• HiB: Reconstituted with DPT vaccine or saline
• Measles and MMR: Reconstituted with distilled water/ sterile water
• In dry form they are highly stable but after mixing with diluent they are highly unstable and hence should be used within 4 hours of reconstitution

Vaccine Strains

BCG	Danish 1331
Measles	Edmonston Zagreb
Mumps	Jeryl Lynn
Rubella	RA 27/3
YF	17D
Varicella	OKA
JE	SA-14-14-2
H1N1	A7/California/ 2009
Typhoral	Ty21a
HIV	mVA (Modified vaccinia ancara)
DengaVaxia	CYD: TDV
Mosquirix	RTS, S (AS01) (World’s first & only licensed malaria vaccine).
Anthrax	Sterne

Cold Chain

• It is the process of maintaining of the temperature of vaccine from point of manufacturing to point of administration

ILR (Ice Lined Refrigerator)

• Kept at PHC
• Vaccines can be stored for up to 1 month
• Minimum electricity required per day is 8 hours 
• If there is no electricity, it can maintain the temperature of all vaccine for 5 days 

Vaccine Carrier

• Used to transport from PHC to the site of immunization and sub-centers 
• It is a non-electronic instrument with 4 ice packs inside it
• Max 16-20 vaccine vials can be placed.
• It can maintain temp for 24-48 hrs. 

Fully Frozen Ice Pack 

• Smallest component of cold chain
• Used at immunization session level
• 2 vaccines are kept in two holes inside the ice pack
• Horizontal mark indicates water filling level. 

Dial Thermometer 

• Used to monitor the temperature of cold chains, especially at PHC inside ILR.
• Based on the principle of Thermocouple
• Temperature is monitored twice a day
• Alcohol stamp thermometer is more sensitive but dial thermometer is easier to use. 

Reverse Cold Chain

• Used in NPEP for transportation of Polio stool samples to lab at 2–8°C
• Collect stool samples from house of the person and send back to the lab where virus isolation and culture is done

Warm chain

• Synonym of kangaroo mother where a newborn is kept against the body of the mother to prevent neonatal hypothermia

Mission Indradhanush

• Aim: 100% immunization coverage of 7 vaccine preventable diseases by 2020.
• BCG, OPV, DPT, Measles, Hepatitis B.
• Further added: JE, IPV, Rota virus, MR, PCV, HiB

Switch Program

• tOPV: P₁, P₂, P₃ → bOPV: P₁, P₃ 
• National Switch Day: 25^th April 2016
• National Validation Day: 9^th May 2016

Vaccine Vial Monitor (VVM)

• Vaccine Vial Monitor 
• It has an outer blue circle, inner white square
• If temperature maintained properly, inner square always remain white
• If temperature is not maintained in 2-8 degrees, the inner white square starts to change in color. If the inner square is lighter than the outer circle, use the vaccine
• If the inner square same or darker than the circle, discard the vaccine
• According to WHO, Grade 1 and 2 can be used. Grade 3 and 4 should be discarded. 
• It is a marker of cold chain maintenance

Vaccine Vial Monitor (VVM)

• BCG
  • 0-80% 
  • 0% for pulmonary Tb
  • Median 50% (only against severe forms of Tb)
• Measles
  • >90% with 1 dose
  • >99% with 2 doses 
  • India has adopted 2 doses of measles vaccine strategy called AMMRS (Accelerated Measles Mortality Reduction Strategy)
• Rubella: >95% (Vaccine with the highest efficacy with single dose)

First Vaccine

• Smallpox vaccine (Developed by Edward Jenner)
• E. Jenner coined the term ‘Vaccination’
• Louis Pasteur coined the term ‘Vaccine,’ also developed Anthrax and Rabies vaccine

To study this topic in more detail, download the PrepLadder app and find in-depth video lectures covering the topic.