On February 11, 2021 the Iowa Department of Public Health (IDPH) hosted a COVID-19 monoclonal antibodies continuing education (CE) webinar. The webinar recording, which is also approved for CE, is now available at no cost. 

During the live webinar, Regeneron panelist, Ron Rideman, was asked about the duration of action of casirivimab and imdevimab. In follow-up, Mr. Rideman provided the following additional clarification to the question regarding how long the antibodies last:

β€œThe half-life of 2400mg of casirivimab is 24 days and for 2400mg of imdevimab, it’s 21 days. Both are more than sufficient to cover a 30-day period. The antibodies may last longer, and perhaps as long as 90 days, but you should only depend upon 30 days to get the full therapeutic effect until we have more data.”

COVID-19 Monoclonal Antibodies and Vaccination:

Please see the following answers to common questions posed on this topic. Note that these recommendations are subject to change as additional data become available.

  • Can I get a COVID-19 vaccine if I have had antibody treatment?
    We do not yet know how effective vaccines are in someone who has previously received an antibody treatment for a COVID-19 infection, or whether the antibody treatment could interfere with your body's own immune response to a vaccine. Once you have had COVID-19, you are very unlikely to be reinfected for three months afterward. So, if you receive an antibody treatment, you should delay receiving a vaccine for three months as a precaution. See CDC: Interim Clinical Considerations for Use of mRNA COVID-19 Vaccines Currently Authorized in the United States.

  • Can I have antibody treatment if I have been vaccinated?
    In the absence of data we are only able to provide suggestions for consideration by providers; the ultimate decision on how to treat an individual in this situation ultimately rests with the provider.
    For individuals who develop COVID-19 following vaccination with a COVID-19 mRNA vaccine, it is reasonable to administer monoclonal antibodies at least two days following the vaccination. The rationale is that the immune response to the vaccine has been initiated by then and the S protein antigen expressed by the mRNA vaccine has largely disappeared from the surface of cells.
    We [FDA] recommend that subsequent vaccination, if administered, occur at least two weeks following the administration of a monoclonal antibody.

For Continuing Education:

Continuing pharmacy education (CPE) for this session has been accredited by CEImpact, an ACPE-accredited provider of continuing pharmacy education. Emergency and trauma services, nurses, pharmacists, pharmacy technicians, physicians, and physician assistants may claim CPE. To obtain your CPE credit, login/create an account at CEimpact.com, enter the appropriate code (see attached), complete the course examination and evaluation, and follow the instructions to access your CPE statement of credit or certificate. The deadline for obtaining credit for the live session is March 11, 2021, and the deadline for obtaining credit for the recorded session is February 11, 2022. For CPE questions or issues, please email team@ceimpact.com