**Core Concept:** Rabies is a viral infection affecting the central nervous system, typically transmitted through the bite of an infected animal like the boy's pet dog. Post-exposure prophylaxis (PEP) is a series of vaccinations and immune globulin administration given to individuals who have been exposed to rabies virus in order to prevent rabies infection.

**Why the Correct Answer is Right:** In this case, the patient has received a complete course of rabies vaccine before being bitten by the dog in December 2018. However, since the vaccination was completed before the exposure, the most recent dose should be administered as soon as possible. Additionally, immune globulin (IG) is recommended for management of rabies post-exposure prophylaxis. IG is a preparation of antibodies isolated from the blood of convalescent individuals who have recovered from rabies. It provides immediate protection against the virus and can be used in conjunction with the vaccine.

**Why Each Wrong Option is Incorrect:**

A. This option suggests administering the vaccine alone, which is incorrect as the patient has already completed the vaccine course before the exposure.
B. This option suggests administering immune globulin alone, which is also incorrect as it should be used in conjunction with the vaccine.
C. This option suggests administering the vaccine at 2 weeks after exposure, which is too late as the patient should receive the next dose as soon as possible.
D. This option suggests administering the vaccine at 3 weeks after exposure, which is also too late and does not take into account the patient's previous vaccination status.

**Clinical Pearl:** In cases of post-exposure prophylaxis for rabies, administration of the vaccine and immune globulin together is crucial for effective prevention of rabies. The correct sequence for administering the vaccine is as follows:

1. Administer two doses on the day of exposure (Day 0)
2. Administer one dose daily for 4 days (Day 1-4)
3. Administer one dose on Day 7
4. Administer one dose on Day 14
5. Administer one dose on Day 28
6. Administer one dose on Day 90
7. Administer one dose on Day 180
8. Administer one dose on Day 365 (1 year)

**Correct Answer Explanation:**

The patient should receive the next dose of vaccine as soon as possible (Day 0) and continue with the recommended schedule for administering the vaccine and immune globulin together. This ensures that the patient has received the vaccine and immune globulin within the recommended time frame for optimal effectiveness.