ReGen-Cov antibody combination prevents Covid-19

The ReGen-Cov antibody combination (casirivimab and imdevimab) has been shown to prevent Covid-19 infection. Results published in the New England Journal of Medicine showed that ReGen could prevent Covid-19 infection among household contacts of Covid infected individuals. Immunodeficiency UK continues to press government to speed up access to this therapy for our community.  

'These trial results underline how important access to these types of therapies is for the primary and secondary community, many of whom have been given no protection against Covid via the vaccination programme. ReGen-Cov has been shown to both prevent and treat Covid-19 infection. We urge the MHRA to license this monoclonal antibody therapy as soon as possible so that it can be used as a long-term prophylaxis treatment to protect our community against Covid-19,' said Dr Susan Walsh, CEO, Immunodeficiency UK.

Key findings:

  • Symptomatic Covid-19 infection developed in 11 of 753 trial participants (1.5%) in the ReGen-Cov treated group compared to 59 of 752 participants in the placebo (non-treated) group (7.8%); resulting in a relative risk reduction of 81.4%.
  • ReGen-Cov prevented symptomatic and asymptomatic infections overall; resulting in a relative risk reduction of 66.4%. 
  • ReGen-Cov reduced the time to resolution of symptoms; median time was two weeks shorter with ReGen than placebo.
  • ReGen-Cov shortened the period of having a high viral load; 0.4 weeks as compared to 1.3 weeks, for the placebo.


  • ReGen-Cov prevented symptomatic Covid-19 and asymptomatic Covid-19 infection in previously uninfected household contacts of infected persons.
  • In patients who became infected ReGen-Cov reduced the duration of symptomatic disease and the duration of viral load.

Posted 9th August 2021