10/07/2026
Hey everyone, Dr. Misner here! We’ve had a lot of questions recently on vaccines, especially what types of vaccines are out there. Here is a brief look at the vaccine types most commonly used in veterinary medicine:
--Killed virus – the actual virus itself is included in the vaccine, but it is dead virus. It does not give as good of immunity as other vaccine types, but since the dead virus is never capable of reproducing/replicating, it is the safest type of vaccine (especially in diseases that are considered fatal such as rabies).
--Modified live virus (MLV) – the actual live virus itself is included in the vaccine, but it has been modified/weakened to prevent any reproduction/replication of the viral particles. It stimulates a good immune response because it acts almost identical to how the true natural virus would present to the immune cells of the body (commonly used in distemper/respiratory type vaccines).
--mRNA – this is a messengerRNA that codes for the viral protein so that the virus itself is not included in the vaccine. The injection contains identical mRNA particles to what the body would be creating if the virus itself was naturally introduced. The mRNA particles then create a genetic code response that matches what the viral particle would do to generate an immune response (this is a newer class of vaccines in the veterinary medicine field).
--Bacterin – this type of vaccine contains portions of bacterial proteins to cause an immune response. Since only portions of the bacteria are present, it cannot cause the actual disease (commonly used in Lyme and Leptospirosis vaccines).
--Avirulent live culture – this type of vaccine uses the live organism but it has been modified so that it is avirulent, meaning that it cannot cause disease. It will only cause the immune response within the body without causing illness (commonly used in oral and nasal vaccines such as Bordetella).
Hopefully this helps provide a little insight on the different vaccine types being utilized for your pet! As always, the most important vaccine is rabies, as this particular disease is almost always fatal and is a significant human health risk as well. There have been 167 positive cases of animal rabies just in Ohio from 2021 to 2025 (bats and raccoons are the most common!). If you have any other questions or concerns, we are always happy to help answer questions!
