Monoclonal antibody therapeutics and vaccines are two of the most effective ways to combat SARS-CoV-2 and subsequent COVID-19 disease. Although there are some similarities between these two methods, there are stark differences we should know.

What is an antibody and how does monoclonal antibody therapy work?

Similar to antibodies which are proteins that the body naturally produces to defend itself against disease, Monoclonal Antibodies are artificially created in the lab, tailor-made to fight the disease they treat. Casirivimab and Imdevimab are monoclonal antibodies that are specifically directed against the spike protein of SARS-CoV-2, designed to block the virus’ attachment and entry into human cells. Two distinct antibodies bind non-competitively to the COVID-19 virus cell surface and prevent the virus from infecting healthy cells.  Using two antibodies protects against the emergence of resistance. Monoclonal antibody therapy is used to treat infections that have already occurred.

How does a vaccine work?

A vaccine, on the other hand, is what we refer to as "active immunity." A vaccine may be a fragment of a virus, an inactivated virus, or a live virus that is no longer infectious. When we inject this into an individual, the immune system responds as if the person were infected with SARS-CoV-2. However, the person will not become ill, and the assault will provide the inoculated person with what is known as "immune memory." Since the body has already learnt how to adapt to the virus, immune memory protects it from infection in the future, helping the body to clear SARS-CoV-2 before it can do any damage. This protective immunity may last for months, years or even a lifetime in certain cases. Vaccines are completely safe and will help people who are otherwise healthy avoid contracting COVID-19 in the future. Vaccines, however, use this to treat a patient who is already ill.

So, what's the difference between the two? Why do we need both?

• Monoclonal antibody therapies give the body antibodies to protect itself, resulting in passive immunity. Vaccines give active immunity by assisting the body in producing its own antibodies.
• Monoclonal antibody therapy treats those who are already infected with the COVID-19 virus. The vaccine trains the immune system to fight against the COVID-19 virus.
• Monoclonal antibody therapy starts working as soon as it is administered. The vaccine offers protection 1-2 weeks after the second dose is given

FDA approved Emergency Use Authorization or EUA for the REGENERON monoclonal antibody treatment. With the FDA's expanded authorization, Regeneron’s antibody cocktail can be given as an injection. The first dose needs to be administered within 96 hours of exposure.