Favipiravir treatment in Thai children with COVID-19: effectiveness, safety, and modeling drug exposure

Sujittra Chaisavaneeyakorn; Nopporn Apiwattanakul; Chonnamet Techasaensiri; Nattakarn Tantawarak; Bandit Thinkhamrop; Supattra Rungmaitree; Siriporn Phongjitsiri; Tavitiya Sudjaritruk; Suvaporn Anugulruengkitt; Pope Kosalaraksa; Thirapa Nivesvivat; Puttichart Khantee; Pornumpa Bunjoungmanee; Panit Takkinsatian; Thiraporn Kanjanaphan; Rudiwilai Samakoses; Tim R. Cressey; Henry Pertinez; Andrew Owen; Kulkanya Chokephaibulkit

doi:10.2478/abm-2026-0011

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Favipiravir treatment in Thai children with COVID-19: effectiveness, safety, and modeling drug exposure

Asian Biomedicine

Volume 20 (2026): Issue 2 (April 2026)

By: Sujittra Chaisavaneeyakorn, Nopporn Apiwattanakul, Chonnamet Techasaensiri, Nattakarn Tantawarak, Bandit Thinkhamrop, Supattra Rungmaitree, Siriporn Phongjitsiri, Tavitiya Sudjaritruk, Suvaporn Anugulruengkitt, Pope Kosalaraksa, Thirapa Nivesvivat, Puttichart Khantee, Pornumpa Bunjoungmanee, Panit Takkinsatian, Thiraporn Kanjanaphan, Rudiwilai Samakoses, Tim R. Cressey, Henry Pertinez, Andrew Owen and Kulkanya Chokephaibulkit

Open Access

|Apr 2026

Abstract

Background

Despite widespread favipiravir (FPV) use for coronavirus disease 2019 (COVID-19) in Thailand, pediatric clinical evidence remains limited.

Objectives

This study evaluated FPV’s effectiveness and safety for treating COVID-19 in children and adolescents.

Methods

This multicenter, retrospective, observational cohort study included patients ≤18 years old testing COVID-19 positive between July 2021 and December 2022 across 11 hospitals in Thailand. Patients were divided into those with and without chest X-ray-confirmed pneumonia. Patients who received FPV were treated with 35 mg/kg twice daily on day 1 and 15 mg/kg twice daily on days 2–5. Pharmacokinetic (PK) modeling estimated plasma exposure in children using scaled Thai adult data.

Results

Of 2,999 patients, 68.2% had no pneumonia. FPV recipients (n = 1,886) were mostly <5 years old, had a fever, infected during the Omicron wave, had lower mean cycle threshold (Ct) values of SARS-CoV-2 gene at diagnosis, and hospitalized compared to non-recipients. FPV treatment significantly shortened fever duration and hospitalization in both pneumonia and non-pneumonia patients. For non-pneumonia patients, being <5 years old, and receiving FPV were associated with complete recovery at discharge. For pneumonia patients, a history of preterm birth, pulmonary disease, and ICU admission reduced the likelihood of complete recovery at discharge. No serious adverse events were reported. PK models predicted that FPV plasma trough concentrations in children ≥10 kg were above efficacy targets.

Conclusions

Early FPV treatment shortened fever duration and hospital stays in children and adolescents with COVID-19, promoting clinical recovery in both pneumonia and non-pneumonia cases.

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Articles in this issue

DOI: https://doi.org/10.2478/abm-2026-0011 | Journal eISSN: 1875-855X | Journal ISSN: 1905-7415

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Language: English

Page range: 96 - 113

Published on: Apr 30, 2026

Published by: Chulalongkorn University

In partnership with: Paradigm Publishing Services

Publication frequency: 6 issues per year

Keywords:

children,

COVID-19,

favipiravir,

pharmacokinetic modeling,

Thailand

Related subjects:

Medicine,

Assistive professions, nursing,

Basic medical science,

Basic medical science, other,

Clinical medicine,

Clinical medicine, other

© 2026 Sujittra Chaisavaneeyakorn, Nopporn Apiwattanakul, Chonnamet Techasaensiri, Nattakarn Tantawarak, Bandit Thinkhamrop, Supattra Rungmaitree, Siriporn Phongjitsiri, Tavitiya Sudjaritruk, Suvaporn Anugulruengkitt, Pope Kosalaraksa, Thirapa Nivesvivat, Puttichart Khantee, Pornumpa Bunjoungmanee, Panit Takkinsatian, Thiraporn Kanjanaphan, Rudiwilai Samakoses, Tim R. Cressey, Henry Pertinez, Andrew Owen, Kulkanya Chokephaibulkit, published by Chulalongkorn University
This work is licensed under the Creative Commons Attribution 4.0 License.

Volume 20 (2026): Issue 2 (April 2026)