Updated June 2026 · ClinicalTrials.gov

RECRUITINGPhase 2 / Phase 3INTERVENTIONAL

A Study of Ziresovir (AK0529) in High-risk Adult With Respiratory Syncytial Virus (RSV) Infection.

A Randomized, Double-blind, Two-stage, Placebo-controlled Phase 2b/3 Clinical Study to Evaluate the Efficacy and Safety of Ziresovir (AK0529) in Adult Patients at High Risk for Respiratory Syncytial Virus (RSV) Infection.

A Study of Ziresovir (AK0529) in High-risk Adult With Respiratory Syncytial Virus (RSV) Infection. (NCT07658534) is a Phase 2 / Phase 3 interventional studying Respiratory Syncytial Virus Infections, sponsored by Shanghai Ark Biopharmaceutical Co., Ltd.. RECRUITING as of the most recent ClinicalTrials.gov update. Talk to your doctor before contacting the trial site.

About This Trial

Respiratory syncytial virus (RSV) is recognized worldwide as a significant pathogen causing lower respiratory tract infection in infants, the elderly, and immunocompromised patients, which may cause bronchiolitis or pneumonia, and affect the cardiovascular system, central nervous system and the renal system, resulting in hospitalization and death risks in children and also high-risk adults, particularly the elderly. The purpose of this study is to evaluate the efficacy of Ziresovir (AK0529) compared to placebo with respect to the time to resolution of RSV lower respiratory tract disease (LRTD) symptoms.

What Stage of Research Is This?

Phase 2 trials evaluate whether a treatment actually works against Respiratory Syncytial Virus Infections and continue monitoring side effects. Phase 2 enrolls larger groups (typically 100–300 patients) and produces the first real efficacy signal. A successful Phase 2 readout is what unlocks the much larger Phase 3 confirmatory trials needed for FDA approval.

This trial is currently recruiting participants. The sponsor has registered the study with ClinicalTrials.gov as actively enrolling, which means new applicants who meet the eligibility criteria can be considered for screening. Trial status can change between updates — confirm current recruiting status with the study contact before traveling for a screening visit.

Target enrollment of 290 participants puts this in the typical range for a Phase 2-style efficacy study or a moderate Phase 3 trial in a focused Respiratory Syncytial Virus Infections subpopulation. At this scale, the study has enough statistical power to detect a clear treatment effect but is not the largest cohort in the field.

Who May Be Eligible (Plain English)

Who May Qualify: - Aged 18-85 years (inclusive), regardless of gender. - Diagnosed with RSV infection by antigen or nucleic acid test within 36 hours before first dose. - Have at least one of the following high-risk conditions for RSV infection: Chronic respiratory disease; heart disease; immunocompromised status; other chronic disease; age ≥65 years. - Presence of at least one new LRTD symptom or worsening of a pre-existing LRTD symptom (specifically: cough, expectoration, wheezing, shortness of breath), with at least one individual symptom rated as moderate or severe (score 2 or 3 per RiiQ Symptom Scale). - Time from symptom onset (or worsening of pre-existing symptoms) to first dose ≤5 days. (Onset defined as time of first RSV-related symptom/sign confirmed by investigator; pre-existing symptoms are those due to underlying conditions) Who Should NOT Join This Trial: - Diagnosed with influenza or COVID-19 infection within 7 days prior to providing willing to sign a consent form. - Suspected bacterial co-infection. - Received any potentially anti-RSV agents (e.g., ribavirin, long-acting interferon) within 5 half-lives prior to the first study dose, or plans to use such agents during the study. - Received prohibited medications, or plans to use prohibited medications during the study. - Has a severe or unstable gastrointestinal, hepatic, renal, hematologic disorder, or malignancy. - Has a known allergy, hypersensitivity, or intolerance to AK0529 or to any excipients in the AK0529 or placebo formulation. - Female participants with a positive pregnancy test result, or who are breastfeeding. - Refusal to use effective contraception during the trial period. Always talk to your doctor about whether this trial is right for you.

These are translations of the protocol\'s inclusion and exclusion criteria, simplified for patients and caregivers. The original clinical text appears below. Eligibility is ultimately confirmed by the trial site\'s screening process — this summary is a starting point for a conversation with your doctor, not a final determination.

Original Eligibility Criteria

View original clinical language

Inclusion Criteria: * Aged 18-85 years (inclusive), regardless of gender. * Diagnosed with RSV infection by antigen or nucleic acid test within 36 hours before first dose. * Have at least one of the following high-risk conditions for RSV infection: Chronic respiratory disease; heart disease; immunocompromised status; other chronic disease; age ≥65 years. * Presence of at least one new LRTD symptom or worsening of a pre-existing LRTD symptom (specifically: cough, expectoration, wheezing, shortness of breath), with at least one individual symptom rated as moderate or severe (score 2 or 3 per RiiQ Symptom Scale). * Time from symptom onset (or worsening of pre-existing symptoms) to first dose ≤5 days. (Onset defined as time of first RSV-related symptom/sign confirmed by investigator; pre-existing symptoms are those due to underlying conditions) Exclusion Criteria: * Diagnosed with influenza or COVID-19 infection within 7 days prior to providing informed consent. * Suspected bacterial co-infection. * Received any potentially anti-RSV agents (e.g., ribavirin, long-acting interferon) within 5 half-lives prior to the first study dose, or plans to use such agents during the study. * Received prohibited medications, or plans to use prohibited medications during the study. * Has a severe or unstable gastrointestinal, hepatic, renal, hematologic disorder, or malignancy. * Has a known allergy, hypersensitivity, or intolerance to AK0529 or to any excipients in the AK0529 or placebo formulation. * Female participants with a positive pregnancy test result, or who are breastfeeding. * Refusal to use effective contraception during the trial period.

Treatments Being Tested

DRUG

Ziresovir (AK0529)

Active Substance: AK0529 Pharmaceutical Form: Enteric Capsules Route of Administration: Oral

DRUG

Placebo

Active Substance: Placebo Pharmaceutical Form: Enteric Capsules Route of Administration: Oral

Locations (9)

Trial sites listed on ClinicalTrials.gov for this study. Site activation status can vary — confirm with the specific site before traveling for a screening visit.

China-Japan Friendship Hospital

Beijing, Beijing Municipality, China

Guangzhou Medical University Panyu Central Hospital

Guangzhou, Guangdong, China

Cangzhou Hospital of Integrated TCM-WM

Cangzhou, Hebei, China

The First Affiliated Hospital of Nanyang Medical College

Nanyang, Henan, China

Henan Infectious Disease Hospital (The Sixth People's Hospital of Zhengzhou)

Zhengzhou, Henan, China

Wuhan Sixth Hospital

Wuhan, Hubei, China

Zhejiang Hospital

Hangzhou, Zhejiang, China

People's Hospital of Rui'an City

Rui’an, Zhejiang, China

Taizhou Hospital of Zhejiang Province

Taizhou, Zhejiang, China

How to Talk to Your Doctor About This Trial

Bring the printable summary of this trial — including the NCT ID (NCT07658534), the sponsor (Shanghai Ark Biopharmaceutical Co., Ltd.), and the key eligibility criteria — to your next appointment. Your doctor can review the inclusion and exclusion criteria against your medical history, lab values, and current treatments to assess whether you are likely to qualify. They can also help you weigh whether trial participation makes sense alongside your existing care plan.

Useful questions to walk through together: What does the trial protocol require beyond standard care? How long is the active treatment phase, and how long is follow-up? Are there study visits at sites I can reach? Who pays for the trial-specific procedures, and who pays for standard-of-care portions? See our 25 questions to ask about clinical trials guide for a more complete checklist.

Authoritative Sources

The official record for this trial lives on ClinicalTrials.gov — the federal registry maintained by the National Library of Medicine at NIH. For background on how this trial fits into the FDA approval pathway, see the FDA drug approval process. For oncology-specific guidance for patients considering trials, the National Cancer Institute publishes patient-oriented overviews. International trial registries are aggregated by the WHO ICTRP.

Frequently Asked Questions

What is the NCT07658534 clinical trial studying?

Who can participate in NCT07658534?

Eligibility for this trial depends on the specific inclusion and exclusion criteria set by the sponsor. The plain-English summary above translates the most important criteria into accessible language; the official clinical text is preserved in the collapsible section underneath. Whether you fit any specific trial is a medical decision your doctor needs to confirm — bring the trial information to your treating physician for a full review against your medical history.

How do I contact the trial site for NCT07658534?

Contact information registered with ClinicalTrials.gov is shown in the sidebar of this page. Before reaching out, confirm with your treating physician that this trial is appropriate for your situation. The trial site will then walk you through the screening process to determine final eligibility.

Is participating in a clinical trial safe?

Clinical trials in the United States are regulated by the FDA and overseen by Institutional Review Boards (IRBs) that review the protocol for safety. Risk varies by trial — Phase 1 studies test new treatments in humans for the first time, while Phase 3 trials use treatments that have already passed earlier safety screening. The informed consent document for any specific trial details the known risks and what to expect. Discuss those risks with your physician before deciding whether to participate.

Where can I verify the data on this page?

Every detail on this page comes directly from the ClinicalTrials.gov API. Click "View on ClinicalTrials.gov" in the sidebar to see the official, unmodified record. The federal record is always authoritative; this page is a structured presentation with a plain-English eligibility translation. For background on how clinical trials are regulated, see the FDA drug approval process documentation.

How This Page Is Built

Every field on this page is pulled directly from the ClinicalTrials.gov API v2 — no estimates, no proxies. The plain-English eligibility translation is generated from the original protocol text and reviewed for fidelity to the underlying clinical criteria. The original clinical text remains visible in the collapsible section above so users and clinicians can verify the translation. Read the full methodology for the data pipeline and known limitations.

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Source: ClinicalTrials.gov API v2 record for NCT07658534. Maintained by the National Library of Medicine at NIH. Public domain. Cite as: "TrialFinderData. NCT07658534. Data: ClinicalTrials.gov."

Medical disclaimer: This page is informational, not medical advice. Talk to your doctor about whether a clinical trial is right for you.

Last updated 2026-06-26 · Data from ClinicalTrials.gov.