Small pox vaccine contains______ virus.

Explanation

**Step-by-Step Solution:**

1. **Identify the Disease**: The question pertains to the smallpox vaccine, which is specifically designed to prevent smallpox, a viral disease characterized by fever and a distinctive skin rash.

2. **Historical Context**: The smallpox vaccine was developed by Edward Jenner in 1796. This historical context is important to understand the origins of the vaccine.

3. **Type of Virus Used**: The smallpox vaccine is made using the cowpox virus. Cowpox is a virus that is closely related to the smallpox virus and was used by Jenner to create immunity against smallpox.

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