## Core Concept
The yellow fever vaccine is a live, attenuated vaccine that provides immunity against yellow fever, a viral disease transmitted by mosquitoes. The vaccine is administered once and is usually valid for 10 years, after which a booster dose may be required for continued protection, especially for travelers to endemic areas.

## Why the Correct Answer is Right
The yellow fever vaccine, once administered, is generally considered to be effective for 10 years. According to the World Health Organization (WHO) and other health guidelines, a booster dose of the yellow fever vaccine is recommended every 10 years for travelers to areas where the disease is endemic. This 10-year validity period is crucial for international travelers, as it determines when they need to get revaccinated to maintain protection against yellow fever.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is not provided, but typically, incorrect options might suggest a shorter or longer validity period without basis in current medical guidelines.
- **Option B:** Similarly, without the specific details of Option B, one might assume it could suggest a different timeframe (e.g., 5 years) that does not align with the standard recommendation.
- **Option C:** This option might propose that the vaccine needs to be repeated more frequently (e.g., every 5 years) or less frequently (e.g., every 20 years), which does not align with current guidelines.
- **Option D:** As the correct answer is listed as D, options A, B, and C are incorrect based on the information provided.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the yellow fever vaccine is valid for 10 years, and a booster dose is recommended every 10 years for continued protection, especially for individuals traveling to or living in areas where yellow fever is endemic. This is crucial for preventing the disease, which can be severe and even fatal.

**Correct Answer: D.**

✓ Correct Answer: C. The ceificate is valid from 10th day to 10 years after vaccination provided it is validated by the official stamp of ministry of health (Govt.of India)