A written assessment from Gilead’s responsible research team: whether, and under what conditions, it would support obeldesivir research for Long COVID.
Gilead Sciences: Gilead Canada and its obeldesivir and antiviral research teams
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Suggestions on the draft are welcome until 22 October 2026. LCAC will then finalize the letter and send it to Gilead Canada.
Preparing campaignCampaign updated: 8 Oct 2026
Whether obeldesivir benefits people with Long COVID remains unproven.
Campaign progress
The letter is being prepared.
The letter has not been sent. Suggestions on the draft are welcome until 22 October 2026; LCAC will then finalize it and confirm the delivery route.
What happens after the letter is sent?
LCAC will record the send date, request a response timeframe, and publish dated summaries of replies or unanswered requests.
Background
What is obeldesivir, and why study it?
Obeldesivir, also called GS-5245, is an experimental drug developed by Gilead. It targets an enzyme the virus uses to copy its genetic material. Researchers have studied it in animals and in large human trials for acute COVID-19 — the initial infection.
Why could an antiviral matter for Long COVID?
Researchers have found viral genetic material in tissues long after infection, including in people with Long COVID. This raises the possibility that persistent virus contributes to illness in some patients. Finding viral material does not always mean the virus is still multiplying, and this is not an explanation for everyone’s Long COVID. Read the tissue study.
Why consider this drug?
Obeldesivir targets a different step in viral replication from Paxlovid. In infected mice, combining obeldesivir with the main antiviral in Paxlovid worked better than either drug alone. That gives researchers a reason to examine the combination; it does not show that it helps people with Long COVID. Read the mechanism and animal study.
What do we still need to find out?
Whether obeldesivir helps established Long COVID remains unproven. Five-day obeldesivir treatment did not significantly shorten acute COVID-19 symptoms in OAKTREE, and longer courses of Paxlovid did not improve the Long COVID outcomes studied in RECOVER-VITAL. Any new study needs a clear rationale, suitable participants and careful safety checks.
LCAC’s next step: prepare a request for Gilead to assess the research case, including longer treatment or combinations where justified, and explain what evidence or conditions would make a study possible.
What we’re asking for
A research assessment and a written response.
The draft asks Gilead to refer the request to the team responsible for obeldesivir and explain whether it would support Long COVID research. These six proposed directions would guide that discussion.
Six proposed research directions
01
Assess renewed SARS-CoV-2 research. Explain whether further obeldesivir research is justified, and what evidence or practical conditions would support it.
Proposed ask
02
Evaluate Long COVID-specific studies. Consider a trial with a clear rationale for the participants selected and the hypothesis being tested.
Proposed ask
03
Assess longer treatment safely. Evaluate appropriate treatment duration, monitoring and stopping arrangements rather than assuming a longer course is better.
Proposed ask
04
Evaluate medicines used together. Assess whether pairing medicines that block different steps in how the virus makes copies of itself merits further research, including safety and interactions.
Proposed ask
05
Explore research collaboration. Consider working with academic investigators, public funders and patient organizations, including support through expertise or study medication.
Proposed ask
06
Include patients in the design. Involve people with Long COVID in outcomes, safeguards and the practical demands of participation.
Proposed ask
These are proposed asks, not requests awaiting a reply. The letter will be finalized before it is sent.
Ways to help
Help prepare a stronger request.
Suggestions are welcome until 22 October 2026. Share the proposal, review one research question or offer your expertise. Times are estimates; a brief or partial contribution is welcome.
The acute COVID-19 trials and existing Long COVID antiviral results inform this request. Any new proposal needs to explain what different question it would test, and how safety would be assessed.
What did the existing trials find?
OAKTREE: a five-day course did not significantly shorten acute COVID-19 symptoms. It reduced the amount of viral genetic material measured in nasal swabs, but that did not translate into a clear symptom benefit. These findings do not answer whether it treats established Long COVID. Read the published results.
BIRCH: recruitment stopped early because hospitalizations and deaths were too infrequent to assess the planned outcome. Gilead said the decision did not reflect a safety or efficacy concern. This was also an acute-COVID study. Read Gilead’s explanation.
RECOVER-VITAL: 15- and 25-day Paxlovid courses showed no evidence of benefit for the Long COVID symptoms studied, involving thinking and memory, regulation of functions such as blood pressure, and symptoms after exertion. It did not test obeldesivir or this drug combination. A new proposal must explain what different question it would test. Read the published results.
Gilead continues to investigate obeldesivir for other viruses. This campaign concerns a possible Long COVID research pathway, rather than assuming all development has stopped. Longer or combined treatment would need its own safety assessment. See Gilead’s current programme.
Who can act
Gilead’s research teams.
Gilead’s obeldesivir and antiviral research teams would need to assess further studies, collaboration and access to study medication. The draft is addressed to Paul Petrelli, Vice President & General Manager of Gilead Sciences Canada Inc., with a request to route it to the responsible team.
Read the full draft letter to Gilead before it is sent, or check one existing antiviral trial to sharpen the ask.
Show 2 items
The proposed letter
Read the draft for Gilead.
Draft for review — Not sent. Revised 8 October 2026.
Intended recipient: Paul Petrelli, Vice President & General Manager, Gilead Sciences Canada Inc. Subject: Request for a written response on evaluating obeldesivir research for Long COVID.
Read the full draft letter
Dear Mr. Petrelli,
I am writing as someone who has lived with Long COVID since early 2020, for more than six years, and as the founder of Long COVID Action Canada, an emerging patient-led initiative.
My immediate request is for a written response from the team responsible for obeldesivir: would Gilead be willing to evaluate supporting research into obeldesivir specifically for Long COVID, including longer treatment durations and combination antiviral approaches where scientifically justified?
Please refer this letter to the appropriate research team and identify a contact who can respond. If Gilead is not considering this work, I would appreciate an explanation of the scientific, safety or practical barriers, and what evidence would be needed to reconsider it.
Obeldesivir is an investigational oral antiviral whose active metabolite inhibits the SARS-CoV-2 RNA polymerase. The five-day OAKTREE trial did not significantly shorten acute COVID-19 symptoms. BIRCH stopped enrollment early because severe outcomes were too infrequent for the planned assessment. These studies did not test treatment of established Long COVID. Short-course findings also do not establish the safety of prolonged or combined treatment.
Gilead continues to investigate obeldesivir for other viruses. This request concerns its potential research role in Long COVID, rather than assuming that all development of the compound has ended.
Existing Long COVID antiviral results need to shape any new proposal. RECOVER-VITAL found no evidence of benefit from 15- or 25-day nirmatrelvir–ritonavir regimens in the cognitive, autonomic and exercise phenotypes studied. It did not test obeldesivir or a polymerase-plus-protease combination. A new proposal should explain what different hypothesis it would test and why.
Viral persistence is one hypothesis under investigation, not an established explanation for every patient’s illness. Combining drugs that act at different stages of replication raises a research question; it does not establish clinical benefit. Longer treatment and combinations require assessment of safety, interactions, participant selection and meaningful patient outcomes.
If the responsible team considers further investigation worthwhile, I would welcome its views on these six directions:
Assess renewed SARS-CoV-2 research. Explain whether further obeldesivir research is justified, and what evidence or practical conditions would support it.
Evaluate Long COVID-specific studies. Consider a trial with a clear rationale for the participants selected and the hypothesis being tested.
Assess longer treatment safely. Evaluate appropriate treatment duration, monitoring and stopping arrangements rather than assuming a longer course is better.
Evaluate combination therapy. Assess whether pairing a polymerase inhibitor with a SARS-CoV-2 protease inhibitor merits further research, including safety and interactions.
Explore research collaboration. Consider working with academic investigators, public funders and patient organizations, including support through expertise or study medication.
Include patients in the design. Involve people with Long COVID in outcomes, safeguards and the practical demands of participation.
After more than six years of illness, I want research that can give patients reliable answers. We need to know both which approaches may help and which do not. A clear explanation of what would make this research possible would be a useful first step.
Please acknowledge receipt, confirm that the letter has reached the responsible team, and indicate when a substantive response can be expected. If another Gilead office should handle it, please arrange that referral.
LCAC intends to publish a dated summary of the response and explain what follows. Please identify any material that cannot be shared publicly.
Thank you for considering this request.
Sincerely, Robert DeRosa Founder, Long COVID Action Canada Long COVID patient advocate hello@longcovidaction.ca
Help make the proposed request more precise by checking one existing Long COVID antiviral trial. You can start with the abstract and choose one part to examine.
Identify what was tested. Note the participants, treatment durations, outcomes and results. Separate the trial’s findings from your interpretation.
Suggest what the draft should address. What should Gilead explain about a different drug, combination, patient group or outcome? RECOVER-VITAL did not test obeldesivir or a polymerase-plus-protease combination.
Send 3–5 brief bullets. Include source links, one uncertainty and an optional proposed change to the draft. A partial note is welcome.
Pause or return whenever useful. A polished report and personal medical history are not needed.
We will check it against the sources before revising the letter. Submitting a note does not guarantee inclusion or publication, and there is no ongoing commitment.
