Viral kinetics in adults with Covid-19 treated with nirmatrelvir-ritonavir or molnupiravir: a population-based, observational cohort study
et al., Virology Journal, doi:10.1186/s12985-025-03057-2, Jan 2026
Observational cohort study of 113,399 COVID-19 outpatients in Vienna showing viral kinetics patterns with nirmatrelvir-ritonavir and molnupiravir treatment. Both antivirals showed improved viral clearance at 7 days, but worse viral clearance at 14 days, suggesting viral rebound.
Potential risks of molnupiravir include the creation of dangerous variants, and mutagenicity, carcinogenicity, teratogenicity, and embryotoxicity1-15. Multiple analyses have identified variants potentially created by molnupiravir16-20. Studies show significantly increased risk of acute kidney injury21, cardiovascular toxocity22, and neurological symptoms21. Treatment may increase viral rebound23,24.
Study covers molnupiravir and paxlovid.
|
relative Ct improvement, 12.3% worse, RR 1.12, p < 0.001, treatment mean 6.5 (±6.76) n=10,752, control mean 7.3 (±14.48) n=90,481, relative differences, day 14.
|
|
relative Ct improvement, 12.7% better, RR 0.87, p < 0.001, treatment mean 5.5 (±6.82) n=10,752, control mean 4.8 (±14.55) n=90,481, relative differences, day 7.
|
| Effect extraction follows pre-specified rules prioritizing more serious outcomes. Submit updates |
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Prager et al., 10 Jan 2026, retrospective, Austria, peer-reviewed, 17 authors.
Contact: markus.zeitlinger@meduniwien.ac.at.
Abstract: Virology Journal
https://doi.org/10.1186/s12985-025-03057-2
Article in Press
Viral kinetics in adults with Covid-19 treated
with nirmatrelvir-ritonavir or molnupiravir: a
population-based, observational cohort study
Received: 11 November 2025
Accepted: 21 December 2025
Cite this article as: Prager M., Ensle D.,
Eser H. et al. Viral kinetics in adults with
Covid-19 treated with nirmatrelvirritonavir or molnupiravir: a populationbased, observational cohort study.
Virol J (2025). https://doi.org/10.1186/
s12985-025-03057-2
A
Marlene Prager, Dominik Ensle, Hubert Eser, Florentin Glötzl, Benjamin Riedl,
Marton Szell, Arschang Valipour, Alexander Zoufaly, Christoph Wenisch, Doris Haider,
Heinz Burgmann, Florian Thalhammer, Florian Götzinger, Bernd Jilma, Ursula
Karnthaler, Markus Zeitlinger & Anselm Jorda
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We are providing an unedited version of this manuscript to give early access to its
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ACCEPTED
ARTICLE IN
MANUSCRIPT
PRESS
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Viral kinetics in adults with Covid-19 treated with
nirmatrelvir-ritonavir
or
molnupiravir:
a
population-based, observational cohort study
Running Title: Viral kinetics after nirmatrelvir-ritonavir and molnupiravir
Marlene Prager1, Dominik Ensle2, Hubert Eser3, Florentin Glötzl4, Benjamin Riedl5,
Marton Szell6, Arschang Valipour7, Alexander Zoufaly8, Christoph Wenisch8, Doris
Haider9, Heinz Burgmann10, Florian Thalhammer11, Florian Götzinger12, Bernd
Jilma1, Ursula Karnthaler2, Markus Zeitlinger1*, Anselm Jorda1
1Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
²Municipal Department for Public Health Services of the City of Vienna, Vienna, Austria
3Municipal Department for Information Technology of the City of Vienna, Vienna, Austria
4Institute
for Ecological Economics, Department for Socioeconomics, Vienna University of Economics and Business,
Vienna, Austria
5Department of Research, Vienna Healthcare Group, Vienna, Austria
6Department of Internal Medicine 2, Emergency Department, Klinik Donaustadt, Vienna,..
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