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0 0.5 1 1.5 2+ Severe case 14% Improvement Relative Risk Hospitalization 35% Paxlovid for COVID-19  Wee et al.  EARLY TREATMENT Is early treatment with paxlovid beneficial for COVID-19? Retrospective 143,698 patients in Singapore (Mar - Dec 2022) Lower hospitalization with paxlovid (p=0.0015) Wee et al., Clinical Microbiology and .., Jun 2023 Favors paxlovid Favors control

Real-world effectiveness of nirmatrelvir/ritonavir against COVID-19 hospitalisations and severe COVID-19 in community-dwelling elderly Singaporeans during Omicron BA.2, BA.4/5 and XBB transmission

Wee et al., Clinical Microbiology and Infection, doi:10.1016/j.cmi.2023.06.016
Jun 2023  
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Retrospective 3,959 paxlovid patients and 139,379 untreated controls, showing lower hospitalization with treatment. Contraindicted patients were excluded.
Confounding by treatment propensity. This study analyzes a population where only a fraction of eligible patients received the treatment. Patients receiving treatment may be more likely to follow other recommendations, more likely to receive additional care, and more likely to receive additional treatments that are not tracked in the data (e.g., nasal/oral hygiene, (B), vitamin D (C), etc.) — either because the physician recommending paxlovid also recommended them, or because the patient seeking out paxlovid is more likely to be familiar with the efficacy of additional treatments. Therefore, these kind of studies may overestimate the efficacy of treatments.
Confounding by contraindication. Hoertel et al. find that over 50% of patients that died had a contraindication for the use of Paxlovid Hoertel. Retrospective studies that do not exclude contraindicated patients may significantly overestimate efficacy.
Black box warning. The FDA notes that "severe, life-threatening, and/or fatal adverse reactions due to drug interactions have been reported in patients treated with paxlovid" FDA.
risk of severe case, 14.0% lower, OR 0.86, p = 0.63, treatment 3,959, control 139,739, adjusted per study, multivariable, RR approximated with OR.
risk of hospitalization, 35.0% lower, OR 0.65, p = 0.002, treatment 3,959, control 139,739, adjusted per study, multivariable, RR approximated with OR.
Effect extraction follows pre-specified rules prioritizing more serious outcomes. Submit updates
Wee et al., 17 Jun 2023, retrospective, Singapore, peer-reviewed, 11 authors, study period 18 March, 2022 - 31 December, 2022.
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This PaperPaxlovidAll
Real-world effectiveness of nirmatrelvir/ritonavir against COVID-19 hospitalisations and severe COVID-19 in community-dwelling elderly Singaporeans during Omicron BA.2, BA.4/5 and XBB transmission
Liang En Wee, An Ting Tay, Calvin Chiew, Barnaby Edward Young, Betty Wong, Ruth Lim, Ching Li Lee, Joyce Tan, Shawn Vasoo, David Chien Lye, Kelvin Bryan Tan
Clinical Microbiology and Infection, doi:10.1016/j.cmi.2023.06.016
Real-world effectiveness of nirmatrelvir/ritonavir against COVID-19 hospitalisations and severe COVID-19 in community-dwelling elderly Singaporeans during Omicron BA.2, BA.4/5 and XBB transmission
Declarations Declaration of interests The authors report no conflicts of interest. Contribution statement LEW contributed to literature search and writing of the manuscript. ATT, CC, BEY, BW, RL, CLL, JT, SV, DCL and KBT contributed to critical review and editing of the manuscript. DCL and KBT provided supervision. KBT, ATT contributed to study design, data collection, and data analysis. All authors had full access to all the data in the study and take responsibility for the decision to submit for publication. KBT and ATT directly accessed and verified the underlying data reported in the manuscript. J o u r n a l P r e -p r o o f
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Pfizer, additional-data-paxlovidtm-supporting Pfizer reports additional data on PAXLOVID supporting upcoming new drug application submission to U
Sackett, Deeks, Altman, Down with odds ratios! Evidence Based Medicine
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Please send us corrections, updates, or comments. Vaccines and treatments are complementary. All practical, effective, and safe means should be used based on risk/benefit analysis. No treatment, vaccine, or intervention is 100% available and effective for all current and future variants. We do not provide medical advice. Before taking any medication, consult a qualified physician who can provide personalized advice and details of risks and benefits based on your medical history and situation. FLCCC and WCH provide treatment protocols.
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