BCG' vaccine is example of

Options

A. Killed vaccine
B. live attenuated vaccine
C. toxoid
D. All of the above

Answer

### Step-by-Step Solution:

1. **Understanding the BCG Vaccine**: The BCG vaccine stands for Bacillus Calmette-Guérin. It is primarily used to protect against tuberculosis (TB).

2. **Identifying Vaccine Types**: Vaccines can be categorized into several types based on how they are made:
- **Attenuated Whole Agent Vaccines**: These contain live but weakened pathogens. Examples include the BCG vaccine, Sabin polio vaccine, and MMR vaccine.
- **Inactivated Whole Agent Vaccines**: These contain killed pathogens. Examples include the Salk polio vaccine and rabies vaccine.
- **Subunit Vaccines**: These use only parts of the pathogen.
- **Conjugated Vaccines**: These are made by combining polysaccharides with proteins to improve immune response.
- **Nucleic Acid Vaccines**: These involve genetic material from the pathogen to elicit an immune response.

3. **Classifying the BCG Vaccine**: The BCG vaccine is classified as an **attenuated whole agent vaccine** because it contains live but weakened bacteria that stimulate an immune response without causing disease.

4. **Conclusion**: Therefore, the BCG vaccine is an example of an **attenuated whole agent vaccine**.