PridCor Therapeutics Announces First Patient Enrolled in Phase 2 SHIELD Study of a Combination Antiviral Regimen for Long COVID
SHIELD Phase 2 Study: first patient enrolled at the Icahn School of Medicine at Mount Sinai; the randomized,
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TUSCALOOSA, Ala., Nov. 10, 2026 (GLOBE NEWSWIRE) — PridCor Therapeutics, LLC, a clinical-stage biopharmaceutical company developing combination antiviral regimens for infection-associated chronic conditions and illnesses (IACCIs), today announced that the first participant has been enrolled in the SHIELD Study, a randomized, double-blind, placebo-controlled Phase 2 study of a combination antiviral regimen in adults with Long COVID. PridCor is conducting the study in collaboration with the Icahn School of Medicine at Mount Sinai, at Mount Sinai’s Cohen Center for Recovery from Complex Chronic Illness. It is registered on ClinicalTrials.gov as NCT07597902, where it is listed as actively recruiting.
Key Highlights
- The first participant has been enrolled in SHIELD at Mount Sinai’s Cohen Center for Recovery from Complex Chronic Illness. The study is listed as recruiting on ClinicalTrials.gov (NCT07597902).
- SHIELD will evaluate valacyclovir, celecoxib, and a 25-day course of nirmatrelvir/ritonavir against placebo in approximately 150 adults aged 18 to 65 with Long COVID. The primary endpoint is the EQ-5D-5L visual analogue scale, a patient-reported rating of overall health.
- The study follows a peer-reviewed case series published in Frontiers in Immunology in January 2026, whose authors concluded that a randomized, placebo-controlled trial was the necessary next step.
About the SHIELD Study
SHIELD (SARS-CoV-2 and Herpesvirus Inhibition for Ending Long COVID Dysfunction) is designed to evaluate the safety and efficacy of combining valacyclovir, celecoxib, and nirmatrelvir/ritonavir (PAXLOVID®) in adults with Long COVID. The regimen is designed to address two proposed drivers of Long COVID: persistent SARS-CoV-2, targeted by nirmatrelvir/ritonavir, and reactivation of latent herpesviruses, targeted by valacyclovir and celecoxib.
The study is enrolling approximately 150 adults aged 18 to 65, who are randomized to one of two arms for a 14-week treatment period. Participants in the combination arm take valacyclovir and celecoxib twice daily for 14 weeks, with nirmatrelvir/ritonavir added for 25 days beginning day 15. Participants in the control arm take matched placebo. To help keep treatment assignments blinded, the placebo matched to nirmatrelvir/ritonavir contains ritonavir, which mimics the drug’s characteristic metallic taste. Participants, care providers, investigators, and outcomes assessors are all blinded to treatment assignment. The primary endpoint is the EQ-5D-5L visual analogue scale (EQ VAS), on which participants rate their overall health from 0 to 100.
David Putrino, PhD, Professor of Rehabilitation and Human Performance at the Icahn School of Medicine at Mount Sinai and Nash Family Director of the Cohen Center for Recovery from Complex Chronic Illness, is Principal Investigator. Amy Proal, PhD, Co-Founder and President of PolyBio Research Foundation and Scientific Director of the Cohen Center, is Co-Investigator.
Valacyclovir, celecoxib, and nirmatrelvir/ritonavir are each approved by the U.S. Food and Drug Administration for other uses. Their use in combination for Long COVID is investigational: the combination has not been approved by the FDA for Long COVID, and SHIELD is designed to evaluate its safety and efficacy for this use. The FDA has confirmed in writing that the study, including its 25-day nirmatrelvir/ritonavir course, meets the criteria for exemption from Investigational New Drug (IND) application requirements. SHIELD is exploratory and will not be submitted to the FDA in support of a Long COVID indication; its results are intended to guide the design of any subsequent study conducted under an IND. The study is conducted under institutional review board oversight.
People who currently meet diagnostic criteria for ME/CFS, or who have received a confirmed ME/CFS diagnosis within the past five years, are not eligible. Full eligibility criteria are listed at clinicaltrials.gov/study/NCT07597902.
Scientific Basis
SHIELD follows an open-label case series published on January 5, 2026 in Frontiers in Immunology (Pridgen WL, Putrino D. Front Immunol. 2026;16:1698271). In that single-site series, 24 adults with Long COVID completed one or both of two regimens: 120 days of valacyclovir plus celecoxib, or the same regimen with a 15-day course of nirmatrelvir/ritonavir added.
At day 120, participants who received the three-drug regimen reported a mean Patient Global Impression of Change (PGIC) score for fatigue of 6.8 on a 7-point scale, compared with 4.8 among those who received valacyclovir and celecoxib alone (p < 0.0001). The three-drug group reported an average 55.3% greater reduction in fatigue than the group that received valacyclovir and celecoxib alone (p < 0.0001). Among participants who received the three-drug regimen, reported improvements remained consistent at 305-day and 731-day follow-up.
The authors described the series as small, open-label, and single-site, and noted that selection bias and the placebo effect may have influenced the results. They concluded that a randomized, double-blind, placebo-controlled trial was the necessary next step. SHIELD is designed to be that trial. It uses a longer, 25-day nirmatrelvir/ritonavir course than the case series, and its primary endpoint, a patient-reported rating of overall health, is broader than the fatigue measures reported in the case series.
“Enrolling the first participant is the moment SHIELD becomes real,” said William “Skip” Pridgen, M.D., Co-Founder and Chief Executive Officer of PridCor Therapeutics. “Our case series was small and open-label. The signal we saw there is exactly what SHIELD is designed to test under blinding and against a placebo arm. People living with Long COVID deserve a rigorous answer.” “SHIELD is the first controlled test of IMC-2 with an added antiviral, and we believe the same approach can be studied in other infection-associated chronic illnesses,” said Brian D. Corday, Co-Founder and Chairman of PridCor Therapeutics.
The full paper is available at doi.org/10.3389/fimmu.2025.1698271.
About Long COVID
Long COVID is an infection-associated chronic condition that can affect nearly every organ system and can persist for years after SARS-CoV-2 infection. An estimated 400 million people worldwide have been affected by Long COVID on a cumulative basis, with an estimated annual global economic impact of approximately $1 trillion (Al-Aly Z, et al. Nature Medicine. 2024;30(8):2148-2164). There are currently no treatments approved by the U.S. Food and Drug Administration for Long COVID.
About PridCor Therapeutics, LLC
PridCor Therapeutics, LLC is a privately held, clinical-stage biopharmaceutical company headquartered in Tuscaloosa, Alabama. The company is developing combination antiviral regimens for infection-associated chronic conditions and illnesses (IACCIs), beginning with Long COVID. Its approach uses IMC-2 (valacyclovir and celecoxib) as a base regimen to which additional antivirals can be added for specific conditions. Its lead investigational regimen combines 14 weeks of IMC-2 with a 25-day course of nirmatrelvir/ritonavir and is designed to address persistent SARS-CoV-2 and reactivated herpesviruses in Long COVID. The company is evaluating additional combinations for other infection-associated chronic illnesses. For more information, visit pridcor.com.
Forward-Looking Statements
This press release contains forward-looking statements, including statements regarding the conduct, enrollment, and timing of the SHIELD Study the potential of PridCor’s investigational regimen, and the company’s development plans. These statements are based on PridCor Therapeutics’ current expectations and are subject to risks and uncertainties that could cause actual results to differ materially, including the risk that enrollment proceeds more slowly than anticipated, that PridCor is unable to obtain the funding needed to complete the study, that results from a randomized, placebo-controlled study differ from observations reported in a small, open-label case series, that the regimen does not show a benefit on the study’s endpoints or raises safety concerns, and that regulatory or institutional requirements change. PridCor undertakes no obligation to update any forward-looking statement except as required by law.
PAXLOVID is a registered trademark of Pfizer Inc.
Media Contact
PridCor Therapeutics, LLC
205-366-0696 | info@pridcor.com
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