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Paxlovid Cuts Severe COVID Risk in People With Prior Infection or Vaccination
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IDWeek, October 16-19, 2024, Los Angeles
Mark Mascolini
Nirmatrelvir-ritonavir (NMR-r, Paxlovid) cut rates of COVID hospital admission, all-cause death, and other signs of advancing disease in people with high risk of COVID progression and some immunity against COVID because of previous bouts of the infection or vaccination for SARS-CoV-2 infection [1]. This pooled analysis of people enrolled in the placebo-controlled EPIC-HR and EPIC-SR trials of NMR-r also found that it slices 2 days off time to sustained symptom relief.
In unvaccinated people with high-risk COVID-19, the placebo-controlled EPIC-HR trial found 85% greater efficacy with NMR-r than placebo in preventing hospital admission for the coronavirus or all-cause death [2]. Pfizer researchers scrutinized data from that trial and one other to see how NMR-r fares in a contemporary population of people with prior COVID or SARS-CoV-2 vaccination. They compared NMR-r with placebo on 4 predetermined clinical outcomes, pooling modified intention-to-treat populations from two randomized, controlled trials, EPIC-HR [2] and EPIC-SR [3]. Participants started NMR-r within 5 days of COVID symptom onset and everyone got tracked through 28 days.
Pooled analysis included 807 people who started NMR-r and 793 who took placebo. The NMR-r group did not differ much from the placebo group in median age (45 overall), gender (50.5% male overall), race (68.7% white, 17.0% Asian/Pacific Islander, 4.3% black), or ethnicity (53.9% Hispanic). Almost half of the study group (44.7%) lived in the United States, while 18.3% lived in Europe and 10.6% in India. The most frequent comorbidities were current cigarette smoking (34.1% overall), hypertension (28.8% overall), and diabetes mellitus (11.8% overall).
Statistical analyses (which differed between outcomes) figured a 73.7% reduced risk of COVID hospital admission or all-cause death with NMR-r than with placebo (P = 0.010). Absolute rate reduction for that outcome stood at 1.40 and number needed to treat to achieve those results at 71. COVID-related medical visits proved 65.0% less likely with NMR-r than with placebo (P = 0.008), with an absolute rate reduction of 4.10 and a number needed to treat of 24. NMR-r reduced risk of severe COVID symptoms 2 to 6 days after treatment began by 22.1% compared with placebo (P = 0.044), with an absolute rate reduction of 3.92 and a number needed to treat of 26. NMR-r proved even more effective in reducing risk of severe COVID symptoms 7 to 28 days after therapy started by 46.6% versus placebo (P = 0.001) for an absolute rate reduction of 6.28 and number needed to treat of 16.
Median time to symptom relief proved 2 days shorter with NMR-r than with placebo-12 versus 14 days (P = 0.047).
Pfizer investigators noted that their analysis is limited by lack of data from the 2022-2023 or 2023-2024 COVID seasons, a sample size too small to permit stratified analyses, and limited number of SARS-CoV-2 Omicron infections. But they cited work indicating that their findings are consistent with real-world observational data in the Omicron era [4-6].
References
1. McLaughlin JM, Leister-Tebbe H, Bao W, et al. Efficacy of nirmatrelvir-ritonavir in high-risk trial participants with prior SARS-CoV-2 infection or vaccination: a pooled analysis. IDWeek, October 16-19, 2024, Los Angeles. Abstract 88.
2. Hammond J, Leister-Tebbe H, Gardner A, et al. Oral nirmatrelvir for high-risk, nonhospitalized adults with Covid-19. N Engl J Med. 2022;14;386:397-1408. doi: 10.1056/NEJMoa2118542. https://pmc.ncbi.nlm.nih.gov/articles/PMC8908851/
3. Hammond J, Fountaine RJ, Yunis C, et al. Nirmatrelvir for vaccinated or unvaccinated adult outpatients with Covid-19. N Engl J Med. 2024;390:1186-1195. doi: 10.1056/NEJMoa2309003. https://www.nejm.org/doi/10.1056/NEJMoa2309003
4. Aggarwal NR, Molina KC, Beaty LE, et al. Real-world use of nirmatrelvir-ritonavir in outpatients with COVID-19 during the era of omicron variants including BA.4 and BA.5 in Colorado, USA: a retrospective cohort study. Lancet Infect Dis. 2023;23:696-705. doi: 10.1016/S1473-3099(23)00011-7. https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(23)00011-7/fulltext
5. Najjar-Debbiny R, Gronich N, Weber G, et al. Effectiveness of paxlovid in reducing severe coronavirus disease 2019 and mortality in high-risk patients. Clin Infect Dis. 2023;76:e342-e349. doi: 10.1093/cid/ciac443. https://academic.oup.com/cid/article/76/3/e342/6599020
6. Lewnard JA, McLaughlin JM, Malden D, et al. Effectiveness of nirmatrelvir-ritonavir in preventing hospital admissions and deaths in people with COVID-19: a cohort study in a large US health-care system. Lancet Infect Dis. 2023;23:806-815. doi: 10.1016/S1473-3099(23)00118-4. https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(23)00118-4/fulltext
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