BCG vaccine is a live bacterial vaccine given for protection against tuberculosis, mainly severe forms of childhood tuberculosis. It stands for Bacillus Calmette Gurrain, the strain of bovine tuberculosis used in the vaccine & attenuated by French scientists Calmette & Gurrain.
BCG is given anytime
from birth to 15 days of life along with the zero dose of oral polio vaccine. It is to be given to all children as part of EPI schedule as recommended by Govt. of India.
Storage and PreparationBCG vaccine is available as a lyophilized powder in an ampoule. Diluent used is buffered saline that is available separately. It is available in a
multidose ampoule containing 20 doses. BCG vaccine stocks can be stored frozen in freezer compartment. Working stock can be stored in the chiller compartment. Even diluents should be stored in the refrigerator's lower racks at 2-80C.
BCG vaccine ampoules should be cut with a file very slowly & not snapped open because it has vacuum inside or else the glass will splinter and fly if cut very suddenly. It may be safer to hold the ampoule in a cloth to avoid injury should the glass splinter. Once prepared, BCG vaccine should be used within 2-3 hours & discarded thereafter.
DosingBCG vaccine is given intradermally i.e. in the layers of skin using 26 no. needle. It is given conventionally over left deltoid area (to differentiate it from small pox vaccine scar, which was conventionally given over right deltoid area). 0.1 ml of vaccine is given using BCG syringe which is a 1 ml. glass syringe with steel plunger to identify it so that it is not used for any other purpose. A wheal or swelling of 6 mm is raised above the surface. No spirit or antiseptic should be applied over the site before injection. Good bath with soap and water is enough to clean the local injection site. At the most one can use normal saline to clean the area.
Neither Govt. of India nor Indian Academy of Pediatrics recommends a booster dose of BCG in India. Some countries like in Gulf recommend one or more booster doses.
EfficacyIn a country like ours where
tuberculosis is endemic, children catch the germs early in life & develop primary complex. In children younger than 3-5 years of age, this can spread & lead to severe & serious forms of childhood tuberculosis like tuberculous meningitis, disseminated tuberculosis, miliary tuberculosis, tuberculosis of organs like bones, urinary tract etc. BCG being live vaccine itself induces a benign primary complex, which leads to some immunity. Such a child when comes in contact with a patient with tuberculosis can still catch the wild germ and develop primary complex, but the spread will be mostly prevented by previous BCG immunity. Hence such children will not develop serious forms of childhood tuberculosis. Such children when they grow as adults can catch tuberculosis again & develop adult form of tuberculosis which is a different type of tuberculosis altogether. This adult type of tuberculosis is not prevented by BCG. Hence BCG does not prevent primary complex but prevents
spread of the primary complex & hence the severe forms of childhood tuberculosis. This explains the outcome of the famous Chingleput trial on BCG vaccine efficacy, which failed to show the protective efficacy of BCG against adult type of tuberculosis.
Incidentally BCG also cross protects against leprosy & the efficacy is 20%.
Reaction to BCGImmediately after the BCG vaccine there is a
small swelling at the injection site which persists for 6-8 hours. After that the swelling disappears & the injection site looks normal. After 6-8 weeks a swelling reappears which looks like a mosquito bite. It grows in size & forms a nodule which breaks open & discharges some fluid & forms an ulcer. The ulcer heals by forming a scar. The whole process takes 2-5 weeks. Some times this process of ulceration & healing recurs 2-3 times. Ultimately the typical puckered scar is formed which remains for lifetime.
Injection site should not be pressed or rubbed. It should not be fomented. Nothing needs to be applied locally. Infact, bath with soap and water should suffice even when it has ulcerated.
If ulceration occurs within 7 days of injection, one must report to the doctor, as it may be a sign of tuberculosis in the child.
ComplicationsBCG does not lead to fever. Hence search for another cause & treat accordingly. In 1-2 % of vaccinees, local lymphadenitis can occur involving axillary lymph nodes or rarely supraclavicular gland, especially if injection is given very high over arm. In children with immune compromised state like AIDS, BCG can lead to progressive systemic disease.
Site of BCG vaccineAs we saw before, 1-2% of children develop local BCG lymphadenitis. If that happens following injection over thigh, it will involve superficial & deep inguinal lymph nodes, which can prove dangerous. Also, by convention BCG scars are looked for over the left arm & hence it is easier to recognize for the doctor when parents do not remember whether BCG was given in the past or not. Hence BCG should only be given over left arm & nowhere else.
BCG adenitisocal lymphadenitis can occur due to superadded infection over BCG ulcer. One should try oral antibiotics & anti-inflammatory with good local hygiene (Soap & water). If the lymph node does not shrink or disappear, it is true BCG lymphdenitis. In these cases if the size of node is less than 10mm - 15mm, if it is firm, non-painful & not matted; no treatment is required & only observation is required. It will usually disappear on its own in the next few months time. If the glands are bigger than 15mm, soft, fluctuating with signs of inflammation or softening, painful and matted or if already an abscess has formed with or without discharge, treatment is definitely required. One can either remove the entire gland surgically or try a course of anti-tuberculous drugs in form of Isoniazid 5 mg/kg/day & Rifampicin 10mg/kg/day on empty stomach for a period of 3-6 months.
BCG not given at birthBCG should be given as early as possible in life, before child comes in contact with tuberculosis. It can be given up to 5 years of age. If it is given beyond 6 months it is preferable to do a prior
Mantoux test to see if the patient is already sensitized to tuberculosis. If patient is already sensitized as shown by positive MT, BCG is not necessary. If prior MT is not done, at least check for accelerated reaction to BCG in first week after vaccination which may suggest presence of tuberculosis in the child.
BCG and developed countriesIn developed countries like USA, very few cases of tuberculosis occur. As BCG does not prevent primary complex or the adult type of tuberculosis no benefit will be derived by routine BCG vaccination in such countries. In fact BCG can interfere with interpretation of Mantoux test done subsequently. Hence BCG is not recommended in USA routinely. With the spread of HIV, incidence of tuberculosis is rising in USA. Under such circumstances they may have to reconsider about routine BCG vaccination.
No BCG scar post vaccinationFormation of scar is neither necessary nor is the only indication of success of BCG vaccine. However it is the only simple & convenient way of determining success of BCG vaccine. It may take 3-6 months for the scar to form. If no scar is visible at all after 6 months one needs to do Mantoux test. If negative, one should give repeat BCG.
Can BCG be given with other vaccines?BCG can be given with other vaccines. In fact, BCG is given along with zero dose of OPV & 1st Dose of Hepatitis B vaccine at birth. As measles can depress cell mediated immunity & as BCG induces cell mediated immunity BCG should not be given along with measles or MMR