Summary of COVID-19 casirivimab/imdevimab studies

1. Regeneron et al., New phase 3 analyses show that a single dose of REGEN-COV® (casirivimab and imdevimab) provides long-term protection against COVID-19

1,683 patient casirivimab/imdevimab prophylaxis RCT: 92% lower hospitalization (p=0.03), 81% fewer cases (p<0.0001), 89% fewer combined hospitalization/ER visits (p=0.06), and 81% fewer symptomatic cases (p<0.0001).
Long-term results for PEP RCT NCT04452318, with 841 baseline seronegative casirivimab/imdevimab patients and 842 placebo patients, showing significantly lower cases with treatment.
Nov 2021, Regeneron, Press Release, https://newsroom.regeneron.com/news-releases/news-release-details/new-phase-3-analyses-show-single-dose-regen-covr-casirivimab-and, https://c19p.org/regeneron5

2. O'Brien et al., Effect of Subcutaneous Casirivimab and Imdevimab Antibody Combination vs Placebo on Development of Symptomatic COVID-19 in Early Asymptomatic SARS-CoV-2 Infection: A Randomized Clinical Trial

204 patient casirivimab/imdevimab early treatment RCT: 85% lower hospitalization (p=0.25), 92% fewer combined hospitalization/ER visits (p=0.03), 33% fewer symptomatic cases (p=0.04), and 40% improved viral clearance (p=0.001).
RCT 204 asymptomatic COVID+ patients, 100 treated with subcutaneous casirivimab/imdevimab, showing lower development of symptoms, lower hospitalization, and faster viral clearance with treatment. Study conducted prior to widespread circulation of delta and omicron in the study locations.
Jan 2022, JAMA, https://jamanetwork.com/journals/jama/article-abstract/2788256, https://c19p.org/obrien2

3. Isa et al., Repeat Subcutaneous Administration of REGEN-COV® in Adults is Well-Tolerated and Prevents the Occurrence of COVID-19

969 patient casirivimab/imdevimab prophylaxis RCT: 93% fewer symptomatic cases (p=0.002) and 93% fewer cases (p=0.002).
RCT 969 patients, 729 treated with monthly subcutaneous casirivimab/imdevimab, showing significantly lower risk of COVID-19 with treatment. There were no grade 3 injection site reactions or hypersensitivity reactions. Slightly more TEAEs were reported with treatment (54.9% vs. 48.3%), due to grade 1-2 ISRs. Serious adverse events were rare and occurred with similar percentages for treatment and control groups. There were no deaths. NCT04519437.
Nov 2021, medRxiv, https://www.medrxiv.org/content/10.1101/2021.11.10.21265889, https://c19p.org/isa

4. Weinreich et al., REGEN-COV Antibody Combination and Outcomes in Outpatients with Covid-19

4,180 patient casirivimab/imdevimab early treatment RCT: 71% lower combined mortality/hospitalization (p=0.001) and 29% faster recovery (p=0.001).
RCT 4,057 outpatients with >=1 risk factor for severe disease, showing significantly lower combined hospitalization/death, and significantly faster recovery with treatment. Median time from onset of symptoms 3 days.
May 2021, NEJM, https://www.nejm.org/doi/full/10.1056/NEJMoa2108163, https://c19p.org/weinreich

5. Regeneron et al., New phase III data shows investigational antibody cocktail casirivimab and imdevimab reduced hospitalisation or death by 70% in non-hospitalised patients with COVID-19

2,696 patient casirivimab/imdevimab early treatment RCT: 71% lower combined mortality/hospitalization (p<0.0001) and 29% faster recovery (p=0.0001).
Press release for new phase III data showing lower hospitalization/mortality, and faster symptom resolution among the subset of patients with at least one risk factor. Some variants may escape antibodies [cell.com].
Mar 2021, Regeneron, Press Release, https://www.roche.com/media/releases/med-cor-2021-03-23.htm, https://c19p.org/regeneron3

6. Regeneron et al., Regeneron Reports Positive Interim Data with REGEN-COV™ Antibody Cocktail used as Passive Vaccine to Prevent COVID-19

409 patient casirivimab/imdevimab prophylaxis RCT: 94% fewer symptomatic cases (p=0.009) and 48% fewer cases (p=0.07).
Interim results of REGEN-COV prophylaxis showing 100% prevention of symptomatic infection (8/223 placebo vs. 0/186 REGEN-COV), and approximately 50% lower overall rates of infection (symptomatic and asymptomatic) (23/223 placebo vs. 10/186 REGEN-COV).
Jan 2021, Regeneron, Press Release, https://www.prnewswire.com/news-releases/regeneron-reports-positive-interim-data-with-regen-cov-antibody-cocktail-used-as-passive-vaccine-to-prevent-covid-19-301214619.html, https://c19p.org/regeneron2

7. Somersan-Karakaya et al., Casirivimab and Imdevimab for the Treatment of Hospitalized Patients With COVID-19

2,252 patient casirivimab/imdevimab late treatment RCT: 3% lower mortality (p=0.92), 31% lower combined mortality/intubation (p=0.03), and 30% higher hospital discharge (p=0.02).
RCT 2,252 hospitalized patients. Results for 1,336 patients on low-flow or no supplemental oxygen are reported, showing lower mortality with casirivimab/imdevimab treatment. Cohorts 2&3 (high-intensity oxygen and mechanical ventilation) were paused mid-trial due to increased deaths in the treatment arm and only mortality results are reported.
Nov 2021, The J. Infectious Diseases, https://academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiac320/6650790, https://c19p.org/somersankarakaya

8. Komagamine et al., The effect of casirivimab with imdevimab on disease progression in nonsevere COVID-19 patients in a single hospital in Japan

128 patient casirivimab/imdevimab early treatment study: 92% lower ICU admission (p=0.04), 68% lower progression (p=0.006), and 29% shorter hospitalization (p=0.001).
Combined retrospective/prospective study in Japan with 53 casirivimab/imdevimab patients and 75 control patients, showing significantly lower progression with treatment.
Dec 2021, J. General and Family Medicine, https://onlinelibrary.wiley.com/doi/full/10.1002/jgf2.516, https://c19p.org/komagamine

9. McCreary et al., Association of subcutaneous or intravenous route of administration of casirivimab and imdevimab monoclonal antibodies with clinical outcomes in COVID-19

1,956 patient casirivimab/imdevimab late treatment PSM study: 93% lower mortality (p=0.009), 56% lower combined mortality/hospitalization (p=0.0003), 48% lower hospitalization (p=0.005), and 40% fewer combined hospitalization/ER visits (p=0.003).
Prospective study comparing subcutaneous and intravenous casirivimab/imdevimab, and comparing to a PSM matched control set, showing significantly lower mortality and hospitalization with treatment. Controls were matched with EUA-eligible risk factors only, authors were unable to determine symptom severity.
Nov 2021, medRxiv, https://www.medrxiv.org/content/10.1101/2021.11.30.21266756, https://c19p.org/mccreary

10. Faraone et al., REGEN-COV antibody cocktail (casirivimab/imdevimab) for the treatment of inpatients with early hospital-acquired COVID-19: a single center experience

34 patient casirivimab/imdevimab early treatment study: 92% lower mortality (p=0.03) and 94% lower need for oxygen therapy (p=0.02).
Retrospective 34 patients with hospital-acquired COVID-19, showing lower mortality and oxygen requirements with early casirivimab/imdevimab treatment.
May 2022, Research Square, https://www.researchsquare.com/article/rs-1170976/v1, https://c19p.org/faraone

11. Wei et al., Real-world Effectiveness of Casirivimab and Imdevimab in Patients With COVID-19 in the Ambulatory Setting: An Analysis of Two Large US National Claims Databases

19,564 patient casirivimab/imdevimab early treatment study: 61% lower combined mortality/hospitalization (p<0.0001) and 61% lower hospitalization (p<0.0001).
Retrospective 4,396 casirivimab/imdevimab patients in the USA, showing lower combined mortality/hospitalization (CDM database) and lower hospitalization (PMTX+ database) with treatment.
Feb 2022, medRxiv, https://www.medrxiv.org/content/10.1101/2022.02.28.22270796, https://c19p.org/wei

12. Wilden et al., Real World Outcomes of Cancer Patients With SARS-CoV-2 Infection Receiving Monoclonal Antibodies

casirivimab/imdevimab early treatment study: 82% lower hospitalization (p=0.004).
Retrospective 395 patients in the USA receiving casirivimab/imdevimab or bamlanivimab, showing lower risk of hospitalization with treatment, statistically significant for casirivimab/imdevimab.
Mar 2022, J. the National Comprehensive Cancer Network, https://jnccn.org/view/journals/jnccn/20/3.5/article-pHSR22-178.xml, https://c19p.org/wilden

13. Webb et al., Real-World Effectiveness and Tolerability of Monoclonal Antibody Therapy for Ambulatory Patients with Early COVID-19

5,651 patient casirivimab/imdevimab early treatment study: 91% lower hospitalization (p=0.0003).
Retrospective 115 patients treated with casirivimab/imdevimab showing lower mortality, hospital admission, and emergency department visits with treatment. Authors incorrectly state that "no other COVID-19 therapies for ambulatory patients have proven effective".
Jun 2021, Open Forum Infectious Diseases, https://academic.oup.com/ofid/advance-article/doi/10.1093/ofid/ofab331/6308074, https://c19p.org/webb2

14. Kip et al., Evolving Real-World Effectiveness of Monoclonal Antibodies for Treatment of COVID-19

2,571 patient casirivimab/imdevimab early treatment study: 46% lower combined mortality/hospitalization (p<0.0001).
Retrospective 2,571 patients treated with mAbs in the USA, and 5,135 control patients, showing lower combined mortality/hospitalization for bamlanivimab, bamlanivimab/etesevimab, casirivimab/imdevimab, sotrovimab, and bebtelovimab, with statistical significance only for casirivimab/imdevimab.
Apr 2023, Annals of Internal Medicine, https://www.acpjournals.org/doi/10.7326/M22-1286, https://c19p.org/kipr

15. Kakinoki et al., Impact of Antibody Cocktail Therapy Combined with Casirivimab and Imdevimab on Clinical Outcome for Covid-19 patients in A Real-Life Setting: A Single Institute Analysis

108 patient casirivimab/imdevimab early treatment study: 58% lower progression (p=0.05).
Retrospective 55 patients in Japan treated a median of 3 days from symptom onset with casirivimab/imdevimab, and 53 control patients, showing lower risk of further treatment including oxygen or antivirals.
Nov 2021, Int. J. Infectious Diseases, https://www.sciencedirect.com/science/article/pii/S1201971222000765, https://c19p.org/kakinoki

16. Miyashita et al., Clinical efficacy of casirivimab-imdevimab antibody combination treatment in patients with COVID-19 Delta variant

922 patient casirivimab/imdevimab early treatment study: 46% lower need for oxygen therapy (p=0.004).
Retrospective 461 patients treated with casirivimab/imdevimab in Japan, and 461 matched controls, showing lower oxygen requirements with treatment.
May 2022, J. Infection and Chemotherapy, https://www.sciencedirect.com/science/article/pii/S1341321X22001611, https://c19p.org/miyashita

17. Hussein et al., Real-world effectiveness of casirivimab and imdevimab among patients diagnosed with COVID-19 in the ambulatory setting: a retrospective cohort study using a large claims database

384,447 patient casirivimab/imdevimab early treatment PSM study: 60% lower combined mortality/hospitalization (p<0.0001).
Retrospective 73,759 outpatients treated with casirivimab/imdevimab, showing lower mortality with treatment. This result is subject to potentially substantial confounding by indication - patients with more severe cases may be more likely to receive treatment, and severity information was unavailable in the database.
Dec 2022, BMJ Open, https://bmjopen.bmj.com/lookup/doi/10.1136/bmjopen-2022-064953, https://c19p.org/hussein2

18. Regeneron et al., Regeneron's REGN-COV2 antibody cocktail reduced viral levels and improved symptoms in non-hospitalized COVID-19 patients

183 patient casirivimab/imdevimab early treatment RCT: 38% faster recovery (p=0.22).
Analysis of the first 275 patients in a trial of the REGN-COV2 antibody cocktail showing reductions in viral load and the time to alleviate symptoms in non-hospitalized patients with COVID-19. Greatest improvements were seen with patients that had not mounted their own effective immune response prior to treatment. The mean time-weighted-average change from baseline nasopharyngeal viral load through Day 7 in the seronegative (no measurable antiviral antibodies) group was a 0.60 log10 copies/mL greater reduction (p=0.03) in patients treated with high dose, and a 0.51 log10 copies/mL greater reduction (p=0.06) in patients treated with low dose, compared to placebo. In the overall population, there was a 0.51 log10 copies/mL greater reduction (p=0.0049) in patients treated with high dose, and a 0.23 log10 copies/mL greater reduction (p=0.20) in patients treated with low dose, compared to placebo. Among seronegative patients, median time to symptom alleviation (defined as symptoms..
Sep 2020, Regeneron, Press Release, https://investor.regeneron.com/news-releases/news-release-details/regenerons-regn-cov2-antibody-cocktail-reduced-viral-levels-and, https://c19p.org/regeneron

19. Cooper et al., Real-world Assessment of 2,879 COVID-19 Patients Treated with Monoclonal Antibody Therapy: A Propensity Score-Matched Cohort Study

9,682 patient casirivimab/imdevimab early treatment study: 77% lower mortality (p=0.18), 48% lower ICU admission (p=0.14), and 52% lower hospitalization (p<0.0001).
Retrospective 2,879 patients and matched controls in the USA, showing significantly lower mortality and hospitalization with bamlanivimab, bamlanivimab/etesevimab, and casirivimab/imdevimab. There was significantly lower hospitalization with casirivimab/imdevimab compared to bamlanivimab or bamlanivimab/etesevimab. PSM and multivariate analysis is only provided for all treatments combined.
Oct 2021, Open Forum Infectious Diseases, https://academic.oup.com/ofid/advance-article/doi/10.1093/ofid/ofab512/6384727, https://c19p.org/cooperr

20. Kneidinger et al., Outcome of lung transplant recipients infected with SARS-CoV-2/Omicron/B.1.1.529: a Nationwide German study

218 patient casirivimab/imdevimab early treatment study: 97% lower severe cases (p=0.45).
Retrospective 218 COVID+ lung transplant patients in Germany, showing no significant difference in severe cases with early casirivimab/imdevimab use.
Sep 2022, Infection, https://link.springer.com/10.1007/s15010-022-01914-8, https://c19p.org/kneidingerr

21. Osugi et al., Clinical Prognosis of Patients With Mild COVID-19 Treated With Casirivimab/Imdevimab in Japan

104 patient casirivimab/imdevimab early treatment study: 24% lower hospitalization (p=0.65).
Retrospective 104 outpatients in Japan, 30 treated with casirivimab/imdevimab, showing no significant difference in hospitalization.
Feb 2022, Cureus, https://www.cureus.com/articles/83767-clinical-prognosis-of-patients-with-mild-covid-19-treated-with-casirivimabimdevimab-in-japan, https://c19p.org/osugi

22. Levey et al., Outcomes of pregnant patients treated with REGEN-COV during the COVID-19 pandemic

86 patient casirivimab/imdevimab early treatment study: 108% higher hospitalization (p=0.15).
Retrospective 86 pregnant COVID-19 patients, 36 treated with casirivimab/imdevimab, showing no significant difference in COVID-19 outcomes with treatment.
Jun 2022, American J. Obstetrics & Gynecology MFM, https://www.sciencedirect.com/science/article/pii/S2589933322001082, https://c19p.org/levey

23. Suzuki et al., Real-world clinical outcomes of treatment with casirivimab-imdevimab among patients with mild-to-moderate coronavirus disease 2019 during the Delta variant pandemic

949 patient casirivimab/imdevimab early treatment PSM study: 45% lower progression (p=0.02).
Retrospective 949 patients in Japan, 314 treated with casirivimab/imdevimab showing significantly lower risk of deterioration with treatment.
Dec 2021, medRxiv, https://www.medrxiv.org/content/10.1101/2021.12.19.21268078, https://c19p.org/suzuki

24. Horby et al., Casirivimab and imdevimab in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial

9,785 patient casirivimab/imdevimab late treatment RCT: 6% lower mortality (p=0.16) and 1% higher ventilation (p=0.88).
RCT 9,785 hospitalized patients in the UK showing lower mortality with casirivimab/imdevimab, with statistical significance reached for baseline seronegative patients.
Jun 2021, The Lancet, https://www.sciencedirect.com/science/article/pii/S0140673622001635, https://c19p.org/recoveryr

25. Shah et al., A Retrospective Cohort Observational Study to Assess the Efficacy of Monoclonal Antibody in Coronavirus Disease 2019 Patients

100 patient casirivimab/imdevimab late treatment study: 14% higher mortality (p=1), no change in ventilation (p=1), 14% lower ICU admission (p=0.68), and 4% lower need for oxygen therapy (p=1).
PSM retrospective 100 hospitalized COVID-19 patients in India showing no benefit with casirivimab/imdevimab treatment. There were no significant differences between groups in need for oxygen therapy, high-flow nasal cannula, noninvasive ventilation, invasive ventilation, ICU admission, hospital or ICU stay, or mortality.
Aug 2024, J. the Association of Physicians of India, https://www.japi.org/article/japi-72-9-e6, https://c19p.org/shah9

26. Iustila-Maran et al., Course of inflammation and infection markers differ in ICU patients with severe COVID-19 under casirivimab- and/or tocilizumab application: an observational study

95 patient casirivimab/imdevimab ICU study: 16% higher mortality (p=0.8).
Retrospective 95 ICU patients showing no significant difference in mortality with casirivimab/imdevimab. There was significantly higher mortality with tocilizumab.
Apr 2024, Research Square, https://www.researchsquare.com/article/rs-4090027/v1, https://c19p.org/iustilamaran

27. Shopen et al., Doubtful Clinical Benefit of Casirivimab-Imdevimab Treatment for Disease Severity Outcome of High-Risk Patients with SARS-CoV-2 Delta Variant Infection

359 patient casirivimab/imdevimab early treatment study: 46% higher severe cases (p=0.26).
Retrospective 359 COVID+ patients in Israel, 116 treated with casirivimab/imdevimab, showing no significant difference with treatment in multivariable analysis.
Jan 2022, medRxiv, https://www.medrxiv.org/content/10.1101/2022.01.29.22270090, https://c19p.org/shopen

28. Williams et al., Effectiveness of REGEN-COV combination monoclonal antibody infusion to reduce risk of COVID-19 hospitalization in pregnancy: A retrospective cohort study

764 patient casirivimab/imdevimab early treatment study: 21% higher need for oxygen therapy (p=0.87), 1% higher severe cases (p=0.99), and 14% lower hospitalization (p=0.9).
Retrospective 764 pregnant patients with COVID-19 in the USA, 88 treated with casirivimab/imdevimab, showing no significant difference in outcomes.
Sep 2022, American J. Obstetrics and Gynecology, https://www.sciencedirect.com/science/article/pii/S0002937822007414, https://c19p.org/williams2

29. Gershengorn et al., The clinical effectiveness of REGEN-COV in SARS-CoV-2 infection with Omicron versus Delta variants

6,284 patient casirivimab/imdevimab early treatment study: 95% higher hospitalization (p=0.09).
Retrospective 2,083 outpatients in the USA, showing higher risk of hospitalization with casirivimab/imdevimab, without statistical significance. There may be significant unadjusted confounding by indication.
Dec 2022, PLOS ONE, https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0278770, https://c19p.org/gershengorn

30. Isa et al., Effect of timing of casirivimab and imdevimab administration relative to mRNA-1273 COVID-19 vaccination on vaccine-induced SARS-CoV-2 neutralising antibody responses: a prospective, open-label, phase 2, randomised controlled trial

293 patient casirivimab/imdevimab prophylaxis RCT: 37% more symptomatic cases (p=0.65).
RCT 293 healthy adults focusing on the timing of casirivimab and imdevimab administration relative to mRNA-1273, but also showing the incidence of COVID-19 for each group, with higher incidence in the casirivimab and imdevimab groups (without statistical significance). Authors note the high prevalence of omicron variants which may explain the lack of efficacy seen.
Sep 2024, The Lancet Infectious Diseases, https://www.sciencedirect.com/science/article/pii/S1473309924004213, https://c19p.org/isa2

31. Bes-Berlandier et al., Management of immunosuppression in lung transplant recipients and COVID-19 outcomes: an observational retrospective cohort-study

91 patient casirivimab/imdevimab prophylaxis study: 67% higher progression (p=0.31).
Retrospective 91 lung transplant recipients with COVID-19 showing no significant difference in poor outcomes with casirivimab/imdevimab or tixagevimab/cilgavimab prophylaxis in univariate analysis.
May 2024, BMC Infectious Diseases, https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-024-09269-1, https://c19p.org/besberlandier

Submit Corrections or Updates

Please send us corrections, updates, or comments. c19early involves the extraction of 100,000+ datapoints from thousands of papers. Community updates help ensure high accuracy. Treatments and other interventions are complementary. All practical, effective, and safe means should be used based on risk/benefit analysis. No treatment 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.

Thanks for your feedback! Please search before submitting papers and note that studies are listed under the date they were first available, which may be the date of an earlier preprint.

Submit

Post

@CovidAnalysis

FAQ

Public domain CC0 1.0