Regeneron Pharmaceuticals has reported positive initial results from an ongoing Phase III clinical trial of antibody cocktail REGEN-COV used as a passive vaccine for preventing Covid-19 in people at high risk of infection.
REGEN-COV is a cocktail of two monoclonal antibodies, namely casirivimab and imdevimab (also known as REGN10933 and REGN10987), and can specifically inhibit SARS-CoV-2 infectivity.
Being conducted jointly with the National Institutes of Health (NIH) unit National Institute of Allergy and Infectious Diseases (NIAID), the trial enrolled more than 2,000 subjects.
People were eligible for the trial if a household person had tested positive for Covid-19.
Passive vaccination offers quick short-term passive immunity, by delivering protective virus-neutralising antibodies, using therapeutic antibody treatments such as REGEN-COV or through breastmilk from mother to child.
An exploratory analysis was conducted on approximately 400 participants who randomly received passive vaccination with REGEN-COV, 1,200mg subcutaneous injections, or placebo.
The results showed that passive vaccination with REGEN-COV provided 100% prevention of symptomatic infection and 50% reduced overall symptomatic and asymptomatic infection rates.
Furthermore, with REGEN-COV therapy, decreased levels and duration of viral shedding in asymptomatic infections was observed.
Regeneron president and chief scientific officer George Yancopoulos said: “These data using REGEN-COV as a passive vaccine suggest that it may both reduce transmission of the virus as well as reduce viral and disease burden in those who still get infected.
“The REGEN-COV antibody cocktail may be able to help break this chain by providing immediate passive immunity to those at high risk of infection, in contrast to active vaccines, which take weeks to provide protection.”
Last month, Regeneron reported encouraging initial data from an ongoing Phase I/II/III clinical trial of its antibody cocktail for treating hospitalised Covid-19 patients needing low-flow oxygen.
In a separate development, Eli Lilly and Company has reported that the Phase III BLAZE-1 trial of Bamlanivimab (LY-CoV555) 2800mg and etesevimab (LY-CoV016) 2800mg combination significantly lowered Covid-19-related hospitalisations and deaths in high-risk patients recently diagnosed with Covid-19.