Effects of antivirals on patients with COVID-19 breakthrough.

Background: Antivirals have been given widely for patients with COVID-19 breakthrough in Asian countries, creating a "black market" for unapproved and unprescribed medications. More evidence is needed to clarify the benefits of antivirals in these settings.

Methods: We conducted a random-sampling retrospective cohort study at a general hospital in Vietnam. We recruited patients with mild-to-moderate COVID-19 breakthrough who were given either standard of care (SoC) alone or SoC + antiviral. Primary outcome was residual respiratory symptoms that lasted > 7 days. Secondary outcome was long COVID-19, diagnosed by specialized physicians. We used logistic regression to measure odds ratio (OR), in addition to a sensitivity and subgroup analyses to further explore the results.

Results: A total of 142 patients (mean age 36.2 ± 9.8) were followed. We recorded residual symptoms in 27.9% and 20.3% of the SoC and SoC + antiviral group, while the figures for long COVID-19 were 11.8% and 8.1%, respectively. Antiviral use was not significantly associated with lower the risks of residual symptoms (OR = 0.51, 95% CI: 0.22-1.20, p = 0.12) or long COVID-19 (OR = 0.55, 95% CI: 0.16-1.90, p = 0.35). The sensitivity and subgroup analyses did not show any significant differences between the study groups (all p > 0.05).

Conclusion: Antivirals were not associated with faster resolution of respiratory symptoms or lower risks of long COVID-19. Further studies should focus on different antivirals to confirm their effects on different sub-populations. Meanwhile, antivirals should only be used in very high-risk patients to avoid excessive costs and harms.