Statistically significant lower risk is seen for hospitalization. 12 studies from 12 independent teams in 6 countries show statistically significant improvements.
Meta analysis using the most serious outcome reported shows 29% [12‑42%] lower risk. Results are similar for higher quality and peer-reviewed studies and worse for Randomized Controlled Trials. Early treatment shows efficacy while late treatment does not, consistent with expectations for an antiviral treatment.
Results are robust — in exclusion sensitivity analysis 12 of 22 studies must be excluded to avoid finding statistically significant efficacy in pooled analysis.
Efficacy is variant dependent. In Vitro studies suggest lower efficacy for omicron BA.1 Liu, Sheward, VanBlargan, BA.4, BA.5 Haars, XBB.1.9.3, XBB.1.5.24, XBB.2.9, CH.1.1 Pochtovyi, and no efficacy for BA.2 Zhou, ХВВ.1.9.1, XBB.1.16, BQ.1.1.45, and CL.1 Pochtovyi. US EUA has been revoked. mAb use may create new variants that spread globally Focosi, Leducq, and may be associated with prolonged viral loads, clinical deterioration, and immune escape Choudhary, Günther, Leducq.
Prescription treatments have been preferentially used by patients at lower risk Wilcock. Retrospective studies may overestimate efficacy, for example patients with greater knowledge of effective treatments may be more likely to access prescription treatments but result in confounding because they are also more likely to use known beneficial non-prescription treatments.
No treatment or intervention is 100% effective. All practical, effective, and safe means should be used based on risk/benefit analysis. Multiple treatments are typically used in combination, and other treatments are more effective.
All data to reproduce this paper and sources are in the appendix.
Covid Analysis et al., Apr 2024, preprint, 1 author.
