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Paxlovid effective among vaccinated individuals

A real-world study has found that paxlovid is still effective against COVID-19 even among those who have been fully vaccinated

The anti-viral drug paxlovid remains effective against severe COVID-19 and mortality even among individuals who have been fully vaccinated according to the findings of a real-world study by Israeli researchers.

Paxlovid is a new anti-viral agent which consists of nirmatrelivir, a protease inhibitor against COVID-19 and ritonavir, which reduces the in vivo metabolism of nirmatrelivir. Published data for the drug (the EPIC-HR trial) suggest that treatment of symptomatic COVID-19 in patients at risk of progression to severe disease, results in an 89% lower risk compared to placebo. However, this evidence for paxlovid was obtained before omicron became the main circulating COVID-19 variant and consequently, the generalisability of the study’s findings are potentially limited. As a result, in the present study, the Israeli team decided to undertake a large, retrospective cohort study of high-risk COVID-19 patients, to assess the effectiveness of paxlovid at preventing progression to severe COVID-19 and subsequent death, during the time that omicron was the main circulating variant.

Using a large, national health service database, the researchers identified all adults (18 years and over) who tested positive for COVID-19 but restricted the search to those who would be suitable candidates for treatment with paxlovid, i.e., those who were older than 60 years, with a body mass index (BMI) greater than 30 and with co-morbidities including diabetes, hypertension and cardiovascular disease. However, unlike the EPIC-HR trial, which excluded individuals who had received COVID-19 vaccines, for the present analysis, researchers permitted inclusion of patients irrespective of their vaccination status. The main outcome of the study was a composite of severe COVID-19 or COVID-19-related mortality. For their analysis, the researchers included demographic and co-morbidity data and which were adjusted for in the analysis.

Paxlovid and progression of COVID-19

A total of 4,737 individuals with a mean age of 68.5 years (42.1% male) were treated with paxlovid and compared with 175,614 individuals who tested positive but who did not receive the drug. In total, 77.8% of those given paxlovid had adequate COVID-19 vaccination compared to 75% of those in the non-paxlovid group.

Overall, the primary outcome occurred in 39 individuals receiving paxlovid compared to 903 in those not given the drug. Paxlovid was therefore associated with a significantly lower risk of severe COVID-19 or mortality (hazard ratio, HR = 0.54, 95% CI 0.39 – 0.75). Moreover, among the whole cohort, having adequate COVID-19 vaccination, was also associated with a significantly lower risk of the primary outcome (HR = 0.20, 95% CI 0.17 – 0.22).

When the analysis was restricted to those diagnosed with COVID-19 when omicron was the main circulating variant, paxlovid was also associated with a greater reduction in the primary endpoint (HR = 0.43, 95% CI 0.64 – 0.85). Interestingly, among those given paxlovid and who were adequately vaccinated, there was still a significant reduction in the primary outcome (HR = 0.62, 95% CI 0.39 – 0.98) as well as among those not vaccinated (HR = 0.52, 95% CI 0.32 – 0.82).

The authors concluded that their study had demonstrated that in a real-world setting and during the period of time when omicron was the dominant variant, paxlovid was associated with a significant reduction in progression of COVID-19 and COVID-19-related mortality.

Najjar-Debbiny R et al. Effectiveness of Paxlovid in Reducing Severe COVID-19 and Mortality in High Risk Patients Clin Infect Dis 2022

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