Primary Phase 3 study Objectives:

Cohort A: To evaluate the efficacy of REGN10933+REGN10987 compared to placebo in preventing symptomatic SARS-CoV-2 infection (broad-term) confirmed by RT-qPCR

Cohort A and Cohort A1: To evaluate the safety and tolerability of REGN10933+REGN10987 following subcutaneous (SC) administration compared to placebo

Cohort B: To evaluate the efficacy of REGN10933+REGN10987 compared to placebo in preventing COVID-19 symptoms (broad-term)

Cohort B and Cohort B1: To evaluate the safety and tolerability of REGN10933+REGN10987 following SC administration compared to placebo

Results

The New England Journal of Medicine on August 4, 2021, published the results of this clinical trial.

RESULTS

Symptomatic SARS-CoV-2 infection developed in 11 of 753 participants in the REGEN-COV group (1.5%) and in 59 of 752 participants in the placebo group (7.8%) (relative risk reduction [1 minus the relative risk], 81.4%; P<0.001). In weeks 2 to 4, a total of 2 of 753 participants in the REGEN-COV group (0.3%) and 27 of 752 participants in the placebo group (3.6%) had symptomatic SARS-CoV-2 infection (relative risk reduction, 92.6%). REGEN-COV also prevented symptomatic and asymptomatic infections overall (relative risk reduction, 66.4%). Among symptomatic infected participants, the median time to resolution of symptoms was 2 weeks shorter with REGEN-COV than with placebo (1.2 weeks and 3.2 weeks, respectively), and the duration of a high viral load (>104 copies per milliliter) was shorter (0.4 weeks and 1.3 weeks, respectively). No dose-limiting toxic effects of REGEN-COV were noted.

CONCLUSIONS

Subcutaneous REGEN-COV prevented symptomatic Covid-19 and asymptomatic SARS-CoV-2 infection in previously uninfected household contacts of infected persons. Among the participants who became infected, REGEN-COV reduced the duration of symptomatic disease and the duration of a high viral load. (Funded by Regeneron Pharmaceuticals and others.