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RecruitingNCT04815096Updated May 8, 2026

Imaging Immune Activation in COVID-19

A Phase 2 interventional study of [18F]F-AraG (2'-deoxy-2'-fluoro-9-β-D-arabinofuranosylguanine) in Covid19 and SARS-CoV Infection, sponsored by CellSight Technologies, Inc.. Recruiting at 1 site in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-05-08.

Sponsored by CellSight Technologies, Inc. · Phase 2, Interventional, and Basic science

From the registry’s dates

  • Started Apr 2021; still recruiting 5 years 6 months later.
Phase
Phase 2
Study type
Interventional
Enrollment
80
Allocation
Not applicable
Ages
18 Years and older
Sex
All
01

Study summary

This is a single center, single arm exploratory imaging study involving up to two intravenous microdoses of [18F]F-AraG (the second tracer dose is optional) followed by whole-body PET-CT imaging in participants with convalescent COVID-19. Up to 80 participants will be enrolled over an accrual period of approximately 48 months.

Read the detailed description

This is a single center exploratory imaging study involving up to two intravenous microdoses of [18F]F-AraG (the second tracer dose is optional) followed by whole-body PET-CT imaging in participants 18 years of age and older with recent SARS-CoV-2 diagnosis and COVID-19 at least 14 days following onset of symptoms. The primary objective is to determine the anatomical distribution of [18F]F-AraG in participant with convalescent COVID-19 approximately 4 weeks and 1 month to 1 year (optional, 1 month to one year following first PET imaging visit) following onset of symptoms (N = 80). Tracer activity will also be compared with uninfected historical control participants enrolled in prior studies. Up to 80 participants will be enrolled in this study who will be identified in the UCSF LIINC longitudinal COVID-19 cohort study. Each participant will undergo one PET-CT scan following 50 +/- 10 minutes uptake following a single bolus injection of [18F]F-AraG. A second optional [18F]F-AraG dose and PET-CT will be offered approximately 1 month to one year following the initial imaging time point.

02

Conditions studied

  • Covid19
  • SARS-CoV Infection

Keywords

  • PET-CT Imaging
  • [18F]F-AraG
03

In context

COVID-19

7,990 studies on the registry are indexed under COVID-19; 466 are open to participants now.

This study's planned enrollment of 80 is below the median of 102 across 4,364 interventional studies indexed under COVID-19.

Browse COVID-19 studies →

Lead sponsor

CellSight Technologies, Inc. is the lead sponsor of 11 studies on the registry; 6 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  • Age >18 years
  • Ability to read and understand written document
  • Have a recent diagnosis of SARS-CoV-2 infection as defined by a prior positive SARS-CoV-2 nucleic acid-based diagnostic test performed in a clinical laboratory on one or more nasopharyngeal or respiratory secretion samples.
  • > 14 days since onset of COVID-19 symptoms (or if no symptoms, from time of initial nucleic acid based diagnostic test).
  • Laboratory evaluations obtained within 60 days prior to entry.

    • count ≥75,000/mm3
    • >1000/mm3
    • (AST) \<3 x
    • Alanine aminotransferase (ALT) \<3 x ULN
    • Calculated (CrCl) ≥60 mL/min as estimated by the Cockcroft-
    • Gault equation

Exclusion criteria

Exclusion Criteria:

  • Any medical condition that would compromise the imaging acquisition, in the opinion of the investigator
  • Participants who are pregnant (female participants of childbearing age will be tested prior to injection of imaging agent at entry visit/initial visit - positive test will exclude from further participation in the study)
  • Participants who are breastfeeding
  • Female participants of (defined as women who have not been for at least 24 consecutive months (i.e., who have had menses within the preceding 24 months), or women who have not undergone surgical sterilization, specifically hysterectomy and/or bilateral oophorectomy or bilateral salpingectomy) must have a negative urine or serum pregnancy test with a sensitivity of at least 25 mIU/mL performed within 24 hours prior to PET imaging. Females of reproductive potential will need to be on 2 forms of (excluding withdrawal or timing methods).
  • Participants who have had prior allogeneic stem cell or solid organ transplant.
  • Screening \<1,000 cells/mm3, count \<75,000 cells/mm3, \< 8 mg/dL, estimated \<60 mL/minute, >3 x , alanine aminotransferase >3 x ULN.
  • Known SARS-CoV-2 shedding within 5 days of PET imaging.
  • Previously diagnosed myelodysplasia syndrome or history of lymphoproliferative disease prior to study entry
  • Active systemic diseases not related to COVID-19.
  • COVID-19 vaccine prior to the first PET imaging session. Participants may receive COVID-19 vaccination after the first PET imaging session and the optional second PET scan, with the scan being performed at least 2 weeks following the most recent vaccine dose.
  • Prior PET scan or therapeutic radiation within 1 year of study enrollment.
Terms in these criteria, in plain language(11)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

Platelets

Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.

Absolute neutrophil count (ANC)

The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.

It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.

ALT and AST (liver enzymes)

Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.

Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.

ULN (upper limit of normal)

The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.

“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.

Creatinine clearance (CrCl)

How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.

Reproductive potential

Able to have children. For women this usually means from the first period until menopause, unless permanently unable to through surgery; for men, unless permanently sterile. Read who the line is about — participants, women, men, or their partners.

Criteria about it usually ask for contraception during the study and for a time after it.

Postmenopausal

Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).

Contraception

Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.

Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.

Hemoglobin (Hb)

The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).

Autoimmune disease

A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.

Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.

05

Study design

Phase
Phase 2
Primary purpose
Basic science
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrollment
80 participants (estimated)

Study arms

  • Experimental
    [18F]F-AraG

    Radiofluorinated imaging agent, \[18F\]F-AraG (2'-deoxy-2'-fluoro-9-β-D-arabinofuranosylguanine) Trade name: VisAcT

    Drug: [18F]F-AraG (2'-deoxy-2'-fluoro-9-β-D-arabinofuranosylguanine)

Interventions

  • Drug[18F]F-AraG (2'-deoxy-2'-fluoro-9-β-D-arabinofuranosylguanine)

    \[18F\]F-AraG is a radiolabeled high affinity substrate for deoxyguanosine kinase (dGK) and a low affinity substrate for deoxycytidine kinase (dCK), which are over-expressed in activated T cells.

    Also known as: VisAcT

06

What researchers measure

Primary outcomes

  1. Anatomical distribution of [18F]F-AraG in participant with convalescent COVID-19 greater than 4 weeks (N = 80). Tracer activity will be compared with sex and age-matched uninfected historical control participants enrolled in prior studies.

    To determine regional uptake of \[18F\]F-AraG in participants with convalescent COVID-19.

    Time frame: 4 weeks

Secondary outcomes

  1. [18F]F-AraG uptake in participants with convalescent COVID-19 over time

    To determine the anatomical distribution of \[18F\]F-AraG in participant with convalescent COVID-19 approximately 4 weeks and 5 months (optional) over time.

    Time frame: 5 months

  2. [18F]F-AraG PET-CT is able to detect differences in T cell activation between convalescent COVID-19 participants and age-matched uninfected historical control participants.

    Determine if \[18F\]F-AraG PET-CT is able to detect differences in T cell activation between convalescent COVID-19 participants with and without persistent symptoms (PASC).

    Time frame: 1 year

  3. [18F]F-AraG uptake correlates with direct blood measures of immune activation and SARS-CoV-2 specific T cell responses.

    Time frame: 1 year

07

Study locations

1 of 1 sites recruiting
  • University of California, San Francisco
    San Francisco, California 94110, United States
    Recruiting
    • Timothy J Henrich, MD · Contacttimothy.henrich@ucsf.edu · 415-206-5518
    • Timothy J Henrich, MD · Principal investigator
    • Henry F Vanbrocklin, PhD · Sub investigator
    • Robert Flavel, MD · Sub investigator
08

References and documents

Individual participant data

Plan to share: No

No publications or documents are linked to this record.

09

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on May 8, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT04815096
Lead sponsor
CellSight Technologies, Inc.
Responsible party
Sponsor
First posted
Mar 24, 2021
Start date
Apr 15, 2021
Primary completion
Oct 1, 2027 (estimated)
Completion
Oct 1, 2028 (estimated)
Last update
May 8, 2026

Study contacts

Timothy Henrich, MD
Contact
timothy.henrich@ucsf.edu
6282065518
Kofi Asare
Contact
Kofi.asare@ucsf.edu
Timothy Henrich, MD
principal investigator · University of California, San Francisco

Oversight

Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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