The active immunity offered by tetanus toxoid is effective in nearly –
**Core Concept**
Active immunity against tetanus is achieved through the production of antibodies against tetanus toxin, which is a potent neurotoxin produced by Clostridium tetani. This immunity is long-lasting and can be transferred to the fetus during pregnancy or to newborns through breast milk.
**Why the Correct Answer is Right**
The tetanus toxoid vaccine induces the production of IgG antibodies against tetanus toxin, which provides long-lasting protection against tetanus infection. This immunity is effective for a duration of 10 years or more after the completion of the primary vaccination series, making it a crucial component of routine vaccination schedules. The mechanism involves the stimulation of B cells to produce IgG antibodies, which bind to and neutralize the tetanus toxin, preventing its entry into neurons and subsequent neurotoxic effects.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the duration of immunity offered by tetanus toxoid is not limited to 5 years. While booster doses may be recommended every 10 years, the immunity itself is longer-lasting.
**Option B:** This option is incorrect because the effectiveness of tetanus toxoid immunity is not limited to 5-10 years. In fact, studies have shown that immunity can last for 20-30 years or more after primary vaccination.
**Option C:** This option is incorrect because the duration of immunity offered by tetanus toxoid is not limited to 5-10 years, and it is not specific to individuals who have received booster doses.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that tetanus toxoid immunity can be boosted with a single dose of tetanus toxoid-containing vaccine, making it a crucial component of post-exposure prophylaxis against tetanus.
**Correct Answer:** C. 20-30 years.