PridCor Therapeutics Advances Phase 2 SHIELD Study of a Combination Antiviral Regimen for Long COVID Toward Enrollment

SHIELD Phase 2 Study: first payment made under the clinical trial agreement with Mount Sinai and study drug ordered; the randomized, double-blind, placebo-controlled study, registered as NCT07597902, plans to enroll approximately 150 adults

TUSCALOOSA, Ala., Sept. 24, 2026 (GLOBE NEWSWIRE) -- PridCor Therapeutics, LLC, a clinical-stage biopharmaceutical company developing combination antiviral regimens for infection-associated chronic illnesses, today announced that it has made the first payment under its clinical trial agreement with the Icahn School of Medicine at Mount Sinai for the SHIELD Study, and that study drug has been ordered in preparation for enrollment. SHIELD is a randomized, double-blind, placebo-controlled Phase 2 study of a combination antiviral regimen in adults with Long COVID. The study will be conducted at Mount Sinai’s Cohen Center for Recovery from Complex Chronic Illness with funding from PridCor, and is registered on ClinicalTrials.gov as NCT07597902. Preliminary screening of potential enrollees has begun at Mount Sinai, with patient enrollment expected to begin once study drug is available.

Key Highlights

• PridCor has made the first payment under its clinical trial agreement with the Icahn School of Medicine at Mount Sinai, and study drug has been ordered in preparation for enrollment.
• 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 at the same time: persistent SARS-CoV-2, targeted by nirmatrelvir/ritonavir, and reactivation of latent herpesviruses, targeted by valacyclovir together with celecoxib.

The study plans to enroll approximately 150 adults aged 18 to 65, who will be randomized to one of two arms for a 14-week treatment period. Participants in the combination arm will take valacyclovir and celecoxib twice daily, with nirmatrelvir/ritonavir added for 25 days, during which the valacyclovir dose is temporarily reduced. Participants in the control arm will take matched placebo. To help keep treatment assignments blinded, the placebo matched to nirmatrelvir/ritonavir contains ritonavir, which mimics the metallic taste associated with the drug. Participants, care providers, investigators, and outcomes assessors will all be blinded to treatment assignment.

The primary endpoint is the EQ-5D-5L visual analogue scale, on which participants rate their overall health from 0 to 100, assessed at baseline and at weeks 4, 8, 12, 16, and 20. Secondary measures include the EQ-5D-5L, PROMIS-29, GSQ-30, and Neuro-QoL Cognitive Function instruments, along with standardized assessments of mood, anxiety, and sleep quality. Safety will be assessed primarily through blood and urine measures.

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 its safety and efficacy for this use have not been established. The FDA has confirmed in writing that the study, including its amended 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 will be 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, will not be 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). On a visual analog scale, 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.

The full paper is available at doi.org/10.3389/fimmu.2025.1698271.

“SHIELD is moving from planning to execution,” said William “Skip” Pridgen, M.D., Co-Founder and Chief Executive Officer of PridCor Therapeutics. “Our case series was small and open-label, and the paper itself concluded that a randomized, placebo-controlled trial had to come next. SHIELD is that trial. It is designed to tell us whether what we observed holds up under blinding and against a placebo arm, and people living with Long COVID deserve that answer.”

About Long COVID
Long COVID is an infection-associated chronic condition that can affect nearly every organ system and can persist for months or 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 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 illnesses, beginning with Long COVID. Its lead investigational approach combines agents with complementary mechanisms of action to address persistent SARS-CoV-2 and reactivating herpesviruses. For more information, visit pridcor.com.

Forward-Looking Statements
This press release contains forward-looking statements, including statements regarding the timing of enrollment in the SHIELD Study, the conduct and results of the study, and the potential of PridCor’s investigational regimen. 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 study drug is not available, or that enrollment does not begin, on the anticipated schedule or at all, 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