Information has been received from a medical student concerning a patient who on an unknown date, was vaccinated with a dose of VARIVAX (Merck) (route and lot number not reported). On an unknown date, the patient developed disseminated varicella or zoster after vaccination with VARIVAX (Merck). The student stated that it was a very sensitive case. Follow up information has been received from the medical student and the physician who indicated that the patient was a 15 year-old female, who in November 2010, was vaccinated with the second dose of VARIVAX (Merck) 0.5 ml, subcutaneously (lot number not reported). The physician did not know when the patient received her first dose. The physician reported that the patient was Human Immunodeficiency Virus (HIV) positive and immunocompromised at present. It was reported that the patient's current cluster of differentiation 4 (CD4) count was significantly decreased - i.e. <4. The physician reported that the patient contracted HIV via transplacental transmission and was likely HIV positive at birth; however, the patient was not diagnosed to be HIV positive until just recently (approximately in May/June 2011 at the age of 15 years). The physician stated that the decreased CD4 count occurred post vaccination. Pre-vaccination CD4 counts were not known as patient was undiagnosed and had not had prior CD4 counts done. Also the physician reported that the patient had a history of a herpes simplex virus (HSV) keratitis (date unknown). The physician stated the diagnosis of HSV keratitis was based on clinical signs/symptoms and not confirmed by lab or other diagnostic testing to be HSV. He stated that in hindsight, and now that the patient was known to be HIV positive, that this prior episode of keratitis could have been either an HSV or a varicella zoster virus (VZV) keratitis, which were the more common causes of infectious keratitis in HIV patients. It was reported that in approximately April 2011, the patient developed a facial rash. The physician stated that the rash was not consistent with or typical of herpes zoster or varicella, and she was not diagnosed with either condition. The patient did not have any disseminated rash - it was strictly confined to her face. A lesion sample from the facial rash was negative for VZV at a local laboratory. A dermatologist saw the patient and diagnosed the facial rash as an acneiform rash. The rash had since resolved and no lesion samples were available for further analysis. Subsequently, in approximately May 2011, the patient developed cerebellar symptoms. The patient was admitted to the hospital and underwent a number of evaluations including a lumbar puncture and magnetic resonance imaging (MRI) of the brain which showed cerebellar lesions. The medical student stated that the patient had positive varicella zoster virus (VZV) in a "PSF" specific pathogen free (SPF) test in a first test of cerebrospinal fluid (CSF). The patient received IV acyclovir as treatment for the event. The patient was subsequently found to be HIV positive (exact date unknown). At the time of the report the patient had not recovered. The events were considered to be disabling by medical assistant. Additional information has been requested.