Shots vs. Vaccines vs. Immunizations: What’s the Difference?

A “shot” is any injection into the body (a muscle, vein or fatty tissue just under the skin) with a needle or a syringe. Shots bypass the digestive system, making them a more efficient way to deliver medication.  

A “vaccine,” when introduced into the body, triggers the immune system to produce antibodies. A vaccine can be a shot, a nasal spray or an oral compound, and some require more than one dose.  

“Immunization” is the result of the immune response. Your body is trained to quickly fight off the disease, meaning you’re protected if you’re exposed.  

“When you break it down, the shot is the method of delivery, the vaccine is the substance being delivered and immunization refers to the process in which the immune system is activated to produce antibodies against a specific virus or bacteria,” explains Erik Hogen, MD, a pediatrician at Scripps Clinic Rancho Bernardo. Dr. Hogen is co-chair of the Scripps Vaccine Committee and chair of the Scripps Clinic pediatric department.  

“Not all shots are vaccines and not all vaccines are shots, but ultimately, immunity from common viruses, like the flu, or once-common diseases, is the goal,” adds Mark Shalauta, MD, a family medicine physician at Scripps Clinic Rancho Bernardo and co-chair of the Scripps Vaccine Committee. 

“Immunization is kind of like updating your antivirus software,” he says. “You’re introducing a vaccine, but your body is doing all the work and making the antibodies.”  

Dr. Shalauta notes that there are limits to the effectiveness of certain shots over time. For example, the RSV antibody lasts about one to two years for adults.  

“Some shots act kind of like a vaccine, though they don’t build long-term immune response. They basically give you the antibodies, but they degrade over time; your body’s not building the antibodies, so it only has immunity temporarily,” he says.  

Your primary care physician has an important role in sharing vaccine recommendations with you to support your health at every stage of your life.  

Factors such as your age, medical history, lifestyle and travel plans can influence which vaccines are appropriate for you. For example, if you have a chronic condition like diabetes or heart disease, certain vaccines may be especially important to reduce your risk of complications.  

Additionally, your doctor can help you stay on schedule with booster shots, ensure you’re protected against emerging diseases and address any concerns you may have about vaccine safety.  

Having a trusted physician as your partner to provide information, answer questions and help you understand the recommendations about vaccinations (for children or adults) is an important resource for you and your family.