Nirmatrelvir cut long COVID risk 26% vs 43% in stopped Norwegian trial
A placebo-controlled trial enrolled only 144 of a planned 2,000 participants before closing early, yet still found fewer long-COVID cases with nirmatrelvir-ritonavir than placebo.
Executive Summary
- A randomized, double-blind, placebo-controlled trial in Norway tested whether treating acute COVID-19 with a 5-day antiviral course could prevent long COVID, moving the question beyond the observational cohort evidence that had only associated antiviral treatment with a lower long-COVID risk.
- Participants treated with the antiviral combination had a lower rate of long-COVID symptoms at 3 months than those on placebo, a difference that reached statistical significance despite the trial enrolling only a small fraction of its planned sample.
- The trial's steering committee halted recruitment early for insufficient enrollment, leaving the result built on a much smaller and less precise sample than the study was designed to analyze.
- The finding gives the antiviral-prevents-long-COVID hypothesis its first randomized support, but the underpowered sample means the result invites replication rather than settling the question.
The finding
The PANORAMIC Norway trial, registered as NCT05852873, tested whether a 5-day course of nirmatrelvir-ritonavir taken within 5 days of COVID-19 symptom onset could prevent long COVID, defined as patient-reported fatigue, dyspnoea, or cognitive symptoms at 3 months. Among 143 participants who completed follow-up, 17 of 66 (26%) in the antiviral group had long-COVID symptoms at 3 months, compared with 33 of 77 (43%) in the placebo group, a relative risk of 0.60 after imputing one missing placebo-group value (95% CI 0.37-0.98, p=0.039). NCT05852873+1PAxlovid loNg cOvid-19 pRevention triAl With recruitMent In the Community in NorwayNCT05852873Nirmatrelvir for acute COVID-19 to prevent long COVID (PANORAMIC Norway): a double-blind, randomised, placebo-controlled trial.Jul 16, 2026
How it was done
The trial was a double-blind, randomized, placebo-controlled study run at three Norwegian sites (Bergen, Oslo, and Alesund), enrolling non-hospitalized adults aged 18 to 65 with PCR- or lateral-flow-confirmed SARS-CoV-2 infection and symptoms for 5 days or fewer. Participants were assigned 1:1 to oral nirmatrelvir 300 mg plus ritonavir 100 mg, or matching placebo, twice daily for 5 days, without stratification, and both the primary long-COVID outcome and safety were assessed in the intention-to-treat population. Enrollment ran from May 12, 2023, to June 11, 2025, reaching 144 participants (66 treated, 78 placebo) against a protocol target of 2,000. Nirmatrelvir+1Nirmatrelvir for acute COVID-19 to prevent long COVID (PANORAMIC Norway): a double-blind, randomised, placebo-controlled trial.Jul 16, 2026PAxlovid loNg cOvid-19 pRevention triAl With recruitMent In the Community in NorwayNCT05852873
Why enrollment fell short
The trial's registry record listed an anticipated enrollment of 2,000 as recently as October 2023, with the study still marked Recruiting and a primary completion date of April 1, 2024. The published trial report states the steering committee stopped recruitment prematurely due to insufficient enrollment, leaving the analysis built on 144 randomized participants, about 7% of the planned sample. That shortfall widens the confidence interval around the treatment effect: the upper bound of 0.98 sits just under the threshold for statistical significance. NCT05852873+1PAxlovid loNg cOvid-19 pRevention triAl With recruitMent In the Community in NorwayNCT05852873Nirmatrelvir for acute COVID-19 to prevent long COVID (PANORAMIC Norway): a double-blind, randomised, placebo-controlled trial.Jul 16, 2026
Safety and tolerability
Five participants in the antiviral group discontinued treatment due to adverse events. Taste or smell changes were more common with nirmatrelvir-ritonavir (57 of 66, or 86%) than placebo (14 of 78, or 18%), as was nausea or vomiting (19 of 66, or 29%, versus 8 of 78, or 10%). Palpitations occurred more often in the placebo group (10 of 78, or 13%) than the treatment group (2 of 66, or 3%), and no severe adverse events were reported in either arm. NirmatrelvirNirmatrelvir for acute COVID-19 to prevent long COVID (PANORAMIC Norway): a double-blind, randomised, placebo-controlled trial.Jul 16, 2026
How it fits prior evidence
The trial's authors describe the antiviral-long-COVID link as previously supported only by cohort studies, which could not rule out that healthier or lower-risk patients were more likely to receive treatment. A randomized, placebo-controlled design removes that source of bias, making this the first trial of its kind to test the hypothesis directly with masked treatment allocation. The authors state the limited sample size precludes firm conclusions and that further clinical trials are warranted. NirmatrelvirNirmatrelvir for acute COVID-19 to prevent long COVID (PANORAMIC Norway): a double-blind, randomised, placebo-controlled trial.Jul 16, 2026
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