Safety, PK, and PD Study of a Vaginal Insert Containing TAF and EVG

Inclusion Criteria: 1. Age 18 to 50 years, inclusive 2. General good health (by volunteer history and per investigator judgment) without any clinically significant systemic disease (including, but not limited to significant liver disease/hepatitis, gastrointestinal disease, kidney disease, thyroid disease, bone disease, and diabetes) and with an intact uterus and cervix. 3. History of regular menstrual cycles, by volunteer report (for cycling women) 4. History of Pap smears and follow-up consistent with standard clinical practice as outlined in the Study Manual or willing to undergo a Pap smear at Visit 1 5. Able to communicate in spoken and written English 6. Willing to give voluntary consent and sign an informed consent form 7. Willing and able to comply with protocol requirements, including abstaining from vaginal activity and product use at specified times 8. Must be protected from pregnancy by one of the following: * Hormonal methods, except vaginal rings and DMPA * Copper IUD * Sterilization of participant or partner * Consistent condom use * Abstinence from penile-vaginal intercourse * Same sex relationship 9. If in a relationship, must be in a mutually monogamous relationship with a partner who is not known to be HIV positive and has no known risk of sexually transmitted infections (STIs) Exclusion Criteria: 1. Positive pregnancy test or plans to become pregnant during the course of the study 2. Currently breastfeeding or planning to breastfeed during the course of the study 3. History of sensitivity/allergy to any component of the study product, topical anesthetic, or to both silver nitrate and Monsel's solution 4. In the last three months, diagnosed with or treated for any STI (For HSV, ideally no outbreaks in the past year. More than two outbreaks in previous 12 month period is exclusionary.) 5. Positive test for Trichomonas vaginalis (TV), Neisseria gonorrhea (GC), Chlamydia trachomatis (CT), HIV, or Hepatitis B surface antigen (HBsAg) 6. Symptomatic bacterial vaginosis (BV) 7. Chronic or acute vulvar or vaginal symptoms (pain, irritation, spotting/bleeding, discharge, etc.) 8. Known blood disorder, including deep vein thrombosis (DVT) and pulmonary embolism (PE), or those that could lead to prolonged or continuous bleeding with biopsy 9. NSAIDS, systemic corticosteroids (e.g. dexamethasone), Endothelin Receptor Antagonists (e.g bosentan), antibiotics, Anticonvulsants (e.g. carbamazepine, oxcarbazepine, phenobarbital, phenytoin), Antimycobacterials (Rifbutin, Rifampin, Rifapentine) anticoagulants or other drugs known to prolong bleeding and/or clotting, antifungals (i.e ketoconazole), or antivirals or antiretroviral (e.g. acyclovir, valacyclovir, Viread®, Atripla®, Emtriva®, or Complera®), St. John's Wort or drugs that may interact with TAF or EVG as specified in the Vitekta and Vemlidy Investigator Brochure, should not be used during the study. 10. Current or anticipated chronic use of non-steroidal anti-inflammatory drugs (NSAIDs) or acetominophen for the duration of the study. 11. Participation in any other investigational trial with use of a drug/device within the last 30 days or planned participation in any other investigational trial with use of a drug/device during the study 12. Grade 2 or higher laboratory abnormality, per the Division of AIDS, National Institute of Allergy and Infectious Disease (DAIDS) Table for Grading the Severity of Adverse Events, or clinically significant laboratory abnormality as determined by the clinician 13. Abnormal finding on laboratory or physical examination or a social or medical condition in the volunteer which, in the opinion of the investigator, would make participation in the study unsafe or would complicate interpretation of data