## **Core Concept**
Influenza vaccines are administered to protect against the influenza virus, which can cause significant morbidity and mortality, especially in high-risk populations such as the elderly, young children, and those with certain chronic health conditions. The vaccines are designed to induce immunity against specific strains of the virus. The method of administration is crucial for the vaccine's effectiveness.

## **Why the Correct Answer is Right**
The correct answer, **Intramuscularly (IM)**, is the standard route for administering inactivated influenza vaccines, which are the most commonly used types. The IM route allows for the vaccine antigens to be processed by immune cells efficiently, leading to a robust immune response. This method also reduces the risk of local reactions compared to intradermal administration and is less likely to cause systemic reactions compared to intravenous administration.

## **Why Each Wrong Option is Incorrect**
- **Option A: Intradermally** - This route is not standard for influenza vaccines. It's sometimes used for certain vaccines like BCG (Bacillus Calmette-Guérin) for tuberculosis.
- **Option B: Subcutaneously** - While some vaccines are administered subcutaneously (e.g., MMR - Measles, Mumps, and Rubella vaccine), this is not the typical route for inactivated influenza vaccines.
- **Option D: Intranasally** - This is actually a correct route of administration but for live attenuated influenza vaccines (LAIV), not the inactivated type. LAIV is sprayed into the nostrils and is an alternative for healthy individuals aged 2 through 49 years.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the influenza vaccine is recommended annually, and its composition can change from year to year based on circulating strains of the virus. This makes it crucial to stay updated on vaccine recommendations.

## **Correct Answer:** . Intramuscularly