Measles vaccine given to contact of measles case exes protective effect within –
**Core Concept**
Measles vaccine provides immunity against measles virus by inducing IgG and IgM antibodies, which confer protection against the disease. The immune response to measles vaccine is influenced by factors such as age, previous exposure to measles, and the presence of underlying immune deficiencies.
**Why the Correct Answer is Right**
The measles vaccine is a live attenuated vaccine that contains a weakened form of the measles virus. It is administered to individuals who have not been previously exposed to measles, and it induces a protective immune response within 7-10 days after vaccination. This timeframe is crucial for preventing measles transmission in close contacts of measles cases. The immune system recognizes the attenuated virus as foreign and mounts an immune response, producing antibodies that neutralize the virus and prevent infection.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the protective effect of measles vaccine is not immediate. It takes time for the immune system to recognize and respond to the attenuated virus.
**Option B:** This option is incorrect because the timeframe for the measles vaccine to exert its protective effect is not as short as 1-2 days.
**Option C:** This option is incorrect because the measles vaccine does not provide immediate protection against measles virus. It takes several days for the immune response to develop and confer protection.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the measles vaccine is not 100% effective, and some individuals may still develop measles despite being vaccinated. However, the vaccine significantly reduces the risk of severe measles and its complications.
**Correct Answer:** B. 7-10 days