Inclusion Criteria:

1. Patients with an immediately life-threatening or serious disease or condition caused
by CMV, ADV, HSV, VAVC, VARV or monkeypox viruses(s).

2. Life expectancy of at least 2 weeks and commitment to continuation of supportive care
for at least 4 weeks.

3. Able to ingest and absorb oral medication (in the judgment of the investigator and
based on lack of significant GI pathology such as small bowel resection or ileus).
[Note: Use of TPN (total parenteral nutrition) is not in and of itself exclusionary
as long as the reason for use would not disqualify the patient based on this
criterion.]

4. Willing and able to understand and provide written informed consent. For minors or
those incapable of providing written informed consent (i.e., incapacitated),
understood, written and informed consent must be provided by a parent or legal
guardian or representative.

5. To the best of his or her (or parent/guardian) knowledge, willing and able to
participate in all required study activities for the duration of the study.

6. In the judgment of the investigator, patients for whom no comparable or satisfactory
therapeutic alternative is available

Exclusion Criteria:

1. Females who are pregnant or currently nursing.

2. Patients with hypersensitivity to cidofovir or CMX001.

3. Patients whose long-term prognosis includes a poor likelihood of survival due to
irreversible organ failure including, for example, patients with frank hepatic
failure and adults with Grade 4 GVHD of the GI tract.

4. Patients who are eligible for enrollment and able to participate in a clinical trial
evaluating CMX001.

5. Patients with any other condition that would, in the judgment of the investigator,
put the patient at increased risk during participation in the study, or interfere
with the conduct of the study.