**Core Concept**
The patient has been diagnosed with COVID-19, a viral respiratory illness caused by the SARS-CoV-2 virus. The management of COVID-19 involves a combination of supportive care and antiviral therapy to reduce the severity of symptoms and prevent complications.

**Why the Correct Answer is Right**
The patient's symptoms, such as high-grade fever, myalgias, cough, and mild sore throat, are consistent with COVID-19. The patient has already been tested positive for COVID-19, and the next step in management would involve initiating antiviral therapy, such as oseltamivir or lopinavir/ritonavir, to reduce the severity of symptoms and prevent complications. Additionally, the patient would require supportive care, including hydration, oxygen therapy, and pain management.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the patient has already been tested positive for COVID-19, and there is no need for further testing. The patient's symptoms are consistent with COVID-19, and the next step in management would involve initiating antiviral therapy.

**Option B:** This option is incorrect because the patient's symptoms are consistent with COVID-19, and there is no need for empiric antibiotic therapy. Antibiotics are ineffective against viral infections such as COVID-19.

**Option C:** This option is incorrect because the patient's symptoms are consistent with COVID-19, and there is no need for empiric antifungal therapy. Antifungals are ineffective against viral infections such as COVID-19.

**Option D:** This option is incorrect because the patient's symptoms are consistent with COVID-19, and there is no need for empiric corticosteroid therapy. Corticosteroids may be used in severe cases of COVID-19 to reduce inflammation, but they are not indicated in this patient.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that COVID-19 can present with a range of symptoms, from mild to severe. Patients with mild symptoms, such as the patient in this scenario, can still transmit the virus to others, highlighting the importance of public health measures, such as social distancing and mask-wearing.

**Correct Answer: D.**