BCG vaccine - Why to give it?

                    BCG Vaccine- Why to give it?



BCG Vaccine
What is BCG vaccine?
  • BCG is bacillus calmette guerin.
  • It ia vaccine to prevent tuberculosis and sever tuberculosis. 
  • BCG vaccine is derived from the bovine tuberculosis strain.
  • It was first developed in 1921 by the French microbiologist, Albert Calmette, and the veterinary surgeon, Camille Guerin.
  • It continues to be the only effective vaccine against tuberculosis.
  • The two common strains in use are Copenhagen (Danish 1331) and Pasteur.
  • Copenhagen (Danish) was produced in India at the BCG Laboratories, Guindy, Tamil Nadu till recently.
  • ​The vaccine contains 0.1–0.4 million live viable bacilli per dose.
  • It is supplied as a lyophilized (freeze-dried) preparation in vacuum sealed, multi-dose, dark colored ampoules or 2 ml vials with normal saline as diluent. 

What type of vaccine is BCG?
  • BCG vaccine is a live vaccine.
  • They are live bacteria without capacity to cause disease.
  • After injecting it the recipient's immunity fights against it like it fights real infection.
  • Thus the recipient is prepared for actual real infection caused by disease causing bacteria by developing their immunity.
  • This is form of active immunity that is recipient generates immunity actively in itself.

Why is BCG vaccine necessary?
  • More than 1 million cases of pediatric tuberculosis occur every year.
  • The proportion of pediatric TB cases registered are increasing. 
  • Prevention of childhood tuberculosis is thus an important priority.

How it is stored?​
  • The vaccine is light sensitive and exposure to ultra violet rays. 
  • In lyophilized form, it can be stored at 2 to 8 degree C for up to 12 months without losing its potency. 

How is it administered?
  • Diluent is for reconstitution. 
  • Sterile normal saline can be used in place of diluent. 
  • BCG vaccine contains no preservative.
  • The reconstituted vaccine is stored at 2 to 8 C, protected from light and is discarded within 4–6 hours of reconstitution.
  • The recommended dose is 0.1 ml or 0.05 ml. 
  • Dosage does not depend on the age and weight of the baby. 
  • BCG injection is strictly intradermal, using a tuberculin syringe and a 26G / 27G needle.
  • Left shoulder at level of deltoid insertion is preferred for injection.
  • The selected site is swabbed clean using sterile saline and local antiseptics are avoided

What happens after BCG injection?​​​
  • ​A wheal of 5 mm at the injection site indicates successful intradermal administration of the vaccine. 
  • BCG adenitis is seem more commonly after subcutaneous administration.
  • Usually shows no visible change for several days.
  • Subsequently, a papule after 2–3 weeks. 
  • Which increases to a size of 4–8 mm at end of 5–6 weeks.
  • Papule heals with ulceration.
  • Scar after 6–12 weeks.
  • In some cases ulcer at injection site persists for weeks before scar appears.
  • No treatment is required for this condition.
  • Secondary infection at injection site may require antimicrobials.
  • Ipsilateral axillary/cervical lymphadenopathy can occur a few weeks/months after BCG injection.
  • Antitubercular therapy is of no benefit in such situations and should not be given.
  • The nodes regress spontaneously after a few months.
  • In some children, the nodes may even liquefy and result in an abscess.
  • Surgical removal of the nodes or repeated needle aspiration is the treatment of choice.
  • Antitubercular therapy is not recommended.
  • Disseminated BCG infection can occur but is extremely rare, may occur in babies with cellular immunodeficiency.
  • BCG should be avoided in the immunocompromised, especially those with cellular immunodeficiency.

When is BCG vaccine given?
  • At birth (for institutional deliveries) or at 6 weeks.
  • Catch up vaccination with BCG is recommended till the age of 5 years.
  • Routine tuberculin testing before catch up vaccination is not needed.
  • BCG is repeated once in children less than 5 years of age in the absence of a reaction/ scar.

How efficacious is BCG vaccine?
  • It decreases 75–86 % chances of getting miliary and meningeal form of the tuberculosis.
  • It decreases chances of getting  pulmonary tuberculosis by 50%.


Routine vaccination:
      -  
Should be given at birth or at first contact.


Catch up vaccination:
     
May be given up to 5 years


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