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COVID-19Phase 2SWISS OPTICOVNCT07406217

OPtimisation of Antiviral Therapy in Immunocompromised COVID-19 Patients

A Phase 2 study testing Paxlovid 5 days and Paxlovid 10 days in people with COVID-19 and Immunodeficiency, run by Calmy Alexandra at 4 sites in Switzerland.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
Search all trials

Trial summary

The overall purpose of the trial is to evaluate the efficacy and safety of possible combination antiviral therapy direct antiviral agents (remdesivir + nirmatrelvir/r) versus the reference monotherapy (nirmatrelvir/r alone) and to assess the efficacy and safety of increasing the nirmatrelvir/r course from 5- to 10… Read more about this study

Who is it for?
Ages 16 years and older
Conditions the study is for
COVID-19, Immunodeficiency
What is being tested?
Paxlovid 5 days and Paxlovid 10 days
Could I receive a placebo?
No, everyone receives an active treatment
How many people
256 participants
Where
4 sitesSwitzerland
Study dates
27 Apr 2023to 30 Jun 2026
Phase
Phase 2
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 16 years and older
  • All sexes
  • No healthy volunteers
  • Child, Adult, Older adult

Who may be able to join

  • Laboratory confirmed SARS-CoV-2 infection by real time RT-PCR or positive antigenic test (commercialized assay)
  • Asymptomatic or mild to moderate COVID-19 (WHO progression scale <5. Patients receiving oxygen therapy for reasons other than a pulmonary COVID-19 are eligible).
  • ≥ 16 years of age;
  • Immunocompromised as defined by ≥ 1 risk factors for severe COVID-19 as assessed by the Federal Office of Public Health (FOPH) list (criteria 5: diseases/treatments leading to immune suppression) or other immunosuppression criteria such as:
  • Severe immunosuppression (e.g., human immunodeficiency virus (HIV) infection with CD4 + T cell count <350 / μl)
  • Neutropenia (<1000 neutrophils / μl) ≥1 week
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  • Lymphocytopenia (<200 lymphocytes/μl)
  • On dialysis treatment
  • Hereditary immunodeficiencies
  • Intake of drugs which suppress the immune system (e.g. glucocorticoids for a long time [an equivalent dose of prednisone >20 mg/day > 3 months], monoclonal antibodies, cytostatics, biological products, everolimus, mTOR inhibitors etc.) in the last 12 months
  • Active cancer under cytostatics or targeted therapy known to be immunosuppressive (e.g., platinum salts, cyclophosphamide, anthracyclines, taxanes, 5-fluorouracil, gemcitabine, purine inhibitors, proteasome inhibitors) or associated with hematologic toxicity (neutropenia, lymphopenia), for example sunitinib, imatinib, regorafenib.
  • Aggressive lymphomas (all types)
  • Acute lymphatic leukemia
  • Acute myeloid leukemia
  • Acute promyelocytic leukemia
  • T prolymphocytic leukemia
  • Primary central nervous system lymphoma
  • Stem cell transplantation
  • Light chain amyloidosis
  • Chronic lymphoid leukemia
  • Multiple myeloma
  • Sickle cell disease
  • Bone marrow transplant
  • Organ transplant
  • Being on the waiting list for an organ transplant
  • Willing and able to comply with study requirements and restrictions as described in the informed consent form (ICF)
  • Enrolled in or a beneficiary of a Social Security program (State Medical Aid (AME) is not a Social Security program) or holders of health insurance.
  • Participant's or its legal representative's signature of the informed consent form

Who cannot join

  • SARS-CoV-2 PCR ≥30 CT at screening
  • Hypersensitivity to study drugs (active substance(s) or excipients)
  • Body weight < 40 kg
  • AST (Aspartate transaminase) and/or alanine transaminase (ALT) > 5 times the upper limit
  • Cirrhosis Child-Pugh score C
  • Is taking or is anticipated to require any prohibited therapies*.
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  • Participation in another interventional clinical study with an investigational compound or device, including COVID-19 therapeutics, where the study intervention is performed in the 28 days preceding the inclusion and the 10 days after the inclusion. Investigators of the different clinical studies should agree on participant's inclusion.
  • Presence of any condition for which, in the opinion of the investigator, participation would not be in participant's best interest or that could prevent, limit, or confound the protocol-specified assessments
  • Having received antiviral treatments against SARS-CoV-2 in the 14 days before the inclusion with exception of those having received one or two doses of nirmatrevir/r in the 24h preceding the inclusion in the study.
  • Pregnant or breastfeeding female

Trial locations and contacts

4 sites in 1 country. Contact the study team or a site near you to ask about taking part.

Alexandra Calmy, MD PhD contact

+41 22 372 98 12

alexandra.calmy@hug.ch

Chiara Fedeli, PhD contact

+41 (0)22 372 9817

chiara.fedeli@hug.ch

Switzerland4 sites, 4 recruiting

  • Basel University Hospital

    Basel, Basel, 4031

    Nina Khanna, +41 61 328 73 25, nina.khanna@usb.ch

    Recruiting

  • Hôpitaux Universitaires de Genève

    Geneva, Canton of Geneva, 1205

    Alexandra Calmy, +41 22 372 98 12, alexandra.calmy@hug.ch

    Recruiting

  • CHUV

    Lausanne, Canton of Vaud, 10-549

    Oriol Manuel, +41 21 314 3020, oriol.manuel@chuv.ch

    Recruiting

  • University Hospital Zurich

    Zurich, Canton of Zurich, 8091

    Nicolas Muller, +41 1 255 37 12, nicolas.mueller@usz.ch

    Recruiting

Other trials in Switzerland

About this study

Official title: OPtimisation of Antiviral Therapy in Immunocompromised COVID-19 Patients: a Randomized Factorial Controlled Strategy Trial: the SWISS OPTICOV Study

The overall purpose of the trial is to evaluate the efficacy and safety of possible combination antiviral therapy direct antiviral agents (remdesivir + nirmatrelvir/r) versus the reference monotherapy (nirmatrelvir/r alone) and to assess the efficacy and safety of increasing the nirmatrelvir/r course from 5- to 10 days in immunocompromised patients diagnosed with asymptomatic or mild to moderate Coronavirus Disease 2019 (COVID-19).

Read the detailed description

This is a randomized, controlled, factorial, superiority trial to evaluate the viral efficacy of direct antiviral agent nirmatrelvir/r + direct antiviral agent remdesivir versus nirmatrelvir/r alone and of 5 days versus 10 days of nirmatrelvir/r in immunocompromised patients diagnosed with asymptomatic or mild to moderate COVID-19. The primary objective is to assess whether (i) a combination antiviral therapy of two antiviral agents (nirmatrelvir/r + remdesivir and/or (ii) an increase in nirmatrelvir/ r duration from 5 to 10 days improves viral efficacy by decreasing the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV- 2) positivity rate by real time polymerase chain reaction (RT-PCR) (cycle threshold CT<32) in nasopharyngeal swabs at day 10 (D10). Patients will be eligible if they are immunocompromised, have confirmed asymptomatic SARS-CoV-2 infection or mild to moderate COVID-19, regardless of symptoms onset, provided that they have no contra-indication to any of the study drugs. A total of 256 patients will be recruited in Switzerland and in France, Italy and Norway (through the parallel protocol ANRS0176s OPTICOV).

Participants not eligible for randomisation or who refuse to participate to the trial for any reason will be proposed to be included in an exploratory non comparative cohort (maximum 97 participants, active only in Switzerland).

Being tested
Paxlovid 5 days, Paxlovid 10 days
Keywords
COVID-19, Immunodepression, SARS-CoV-2, Paxlovid, Veklury, Viral load
Medical subject headings
COVID-19, Immunologic Deficiency Syndromes

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Paxlovid 5 daysDrug

    Nirmatrelvir/r 300mg/100 mg bid will be given for 5 days, orally. Nirmatrelvir/r is a combination of two molecules: nirmatrelvir which is a protease inhibitor (against 3CL) and ritonavir which has a booster role. Nirmatrelvir/r (marketed by Pfizer under the brand name Paxlovid®) is indicated for the treatment of COVID-19 in adults who do not require supplemental oxygen and who are at increased risk for progressing to severe COVID-19.

  • Paxlovid 10 daysDrug

    Nirmatrelvir/r 300mg/100 mg bid will be given for 10 days, orally.

Study groups in NCT07406217
Study groupRoleWhat they receive
Nirmatrelvir/ritonavir (nirmatrelvir/r) 5 days aloneOtherNirmatrelvir/r 300mg/100 mg bis in die (twice a day, bid) will be given for 5 days, orally. Nirmatrelvir/r is a combination of two molecules: nirmatrelvir which is a protease inhibitor (against 3CL) and ritonavir which has a booster role. Nirmatrelvir/r (marketed by Pfizer under the brand name Paxlovid®) is indicated for the treatment of COVID-19 in adults who do not require supplemental oxygen and who are at increased risk for progressing to severe COVID-19. Paxlovid® for 5 days is the standard of care.
Receives: Drug: Paxlovid 5 days
Nirmatrelvir/ritonavir (nirmatrelvir/r) 10 days aloneExperimentalIntervention Nirmatrelvir/r 300mg/100 mg bid will be given for 10 days, orally.
Receives: Drug: Paxlovid 10 days
Nirmatrelvir/ritonavir (nirmatrelvir/r) 5 days + remdesivir single doseExperimentalNirmatrelvir/r 300mg/100 mg bid will be given for 5 days, orally. Nirmatrelvir/r is a combination of two molecules: nirmatrelvir which is a protease inhibitor (against 3CL) and ritonavir which has a booster role. Nirmatrelvir/r (marketed by Pfizer under the brand name Paxlovid®) is indicated for the treatment of COVID-19 in adults who do not require supplemental oxygen and who are at increased risk for progressing to severe COVID-19. Remdesivir "flash", 200mg, intravenous. Remdesivir (marketed by Gilead under de brand name Veklury®) is indicated in patients with pneumonia requiring supplemental oxygen (inpatients), as well as in outpatients who are at increased risk of progressing to severe COVID-19. The mode of action characterize remdesivir as a direct-acting antiviral compound.
Receives: Drug: Paxlovid 5 days
Nirmatrelvir/ritonavir (nirmatrelvir/r) 10 days + remdesivir single doseExperimentalNirmatrelvir/r 300mg/100 mg bid will be given for 10 days, orally. Remdesivir "flash", 200mg, intravenous. Remdesivir (marketed by Gilead under de brand name Veklury®) is indicated in patients with pneumonia requiring supplemental oxygen (inpatients), as well as in outpatients who are at increased risk of progressing to severe COVID-19. The mode of action characterize remdesivir as a direct-acting antiviral compound.
Receives: Drug: Paxlovid 10 days

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Virological

    Percentage of patients with SARS-CoV-2 viral load <32 cycle threshold (CT) by real-time RT-PCR in nasopharyngeal swabs at D10 after treatment initiation.

    Measured: Day 10

Secondary outcomes (19)

  1. Virological

    Percentage of patients with SARS-CoV-2 viral load <32 CT by real-time RT-PCR in nasopharyngeal swabs at D5, D14 and D21 after treatment initiation

    Measured: Day 5, Day 14, Day 21

  2. Virological

    Percentage of patients with detectable SARS-CoV-2 viremia at D5, D10 and D14

    Measured: Day 5, Day 10, Day 14

  3. Virological

    Decrease of SARS-CoV-2 viral load measured by copies/ml by nasopharyngeal swab at D5, D10, D14, D21 and at D5, D10 and D14 in blood samples comparatively to screening

    Measured: Day 5, Day 10, Day 14, Day 21

  4. Virological

    Number of de novo mutations after sequencing on nasopharyngeal swabs at D5, D10, D14 and D21 comparatively to screening

    Measured: Day 5, Day 10, Day 14, Day 21

  5. Virological

    To assess the phenotypic resistance (Half maximal inhibitory concentration (IC50) increase) against treatment for viral strains cultured from nasopharyngeal swabs at D5, D10, D14 and D21 comparatively to screening

    Measured: Day 5, Day 10, Day 14, Day 21

  6. Virological

    Time to first negative SARS-CoV-2 RT-PCR (CT<32) until D90

    Measured: Day 90

  7. Virological

    Absence of ability to cultivate virus from viral cultures from nasopharyngeal swabs at D5, D10, D14 and D21

    Measured: Day 5, Day 10, Day 14, Day 21

  8. Clinical

    Percentage of patients with sustained resolution or abatement of symptoms defined as a inFLUenza Patient-Reported Outcome Plus (FLU-PRO-Plus) score ≤1 at D5, D10, D14, D21 and D28

    Measured: Day 5, Day 10, Day14, Day 21, Day 28

  9. Clinical

    All-cause hospitalization and/or death at D28

    Measured: Day 28

  10. Clinical

    Hospitalization at D28

    Measured: Day 28

  11. Clinical

    Death at D28

    Measured: Day 28

  12. Clinical

    inFLUenza Patient-Reported Outcome Plus (FLU-PRO-Plus) scale at D5, D10, D14, D21, D28 and D90. Scores range from 0 (symptom free) to 4 (very severe symptoms).

    Measured: Day 5, Day 10, Day 14, Day 21, Day 28, Day 90

  13. Clinical

    Rate of Post-COVID19 condition at D90 according to the World Health Organisation (WHO) October 2021 definition

    Measured: Day 90

  14. Clinical

    Percentage of participants with an adverse event (AE) or serious adverse event (SAE) or AE leading to treatment discontinuation up to D90

    Measured: Day 90

  15. Clinical

    Adherence to nirmatrelvir/r with patient-reported adherence and nirmatrelvir/r residual plasma dosage at D5 and D10, if applicable

    Measured: Day 5, Day 10

  16. Clinical

    Number of drud-drug interactions who led to dosage adjustment of other patient's drugs

    Measured: Day 10

  17. Clinical

    Immunosuppressors residual concentrations, if applicable

    Measured: Day 10

  18. Clinical

    Percentage of patients with specific retreatment (by antiviral, anti-inflammatory drug or convalescent plasma) through D90

    Measured: Day 90

  19. Clinical

    Number of drug-drug interactions (DDIs) which led to dosage adjustment of other patient's drugs

    Measured: Day 10

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted12 Feb 2026
  2. Study start27 Apr 2023
  3. Primary completion10 Apr 2026 (estimated)
  4. Study completion30 Jun 2026 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 2
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Masking
None (open label)
Enrolment
256 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07406217
Sponsor's protocol ID
2022-01720
Other IDs
62987, FNS 320003B_212963
Acronym
SWISS OPTICOV
Status last verified
Feb 2026
First submitted
5 Feb 2026
Last updated
18 Feb 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
No: Individual Participant Data are described in the study protocol

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing Paxlovid 5 days and Paxlovid 10 days in people with COVID-19 and Immunodeficiency, run by Calmy Alexandra at 4 sites in Switzerland.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 28 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 18 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 4 sites in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Alexandra Calmy, MD PhD (+41 22 372 98 12, alexandra.calmy@hug.ch), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Virological (time frame: Day 10). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07406217.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 18 Feb 2026.

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