About IAC
A-Z Index
Immunization Action Coalition
IAC Home
Ask the Experts

Ask the Experts

Experts from the CDC Answer Questions About Vaccines

Vaccine Index
Topic index
View All
Meet the Experts
From the National Center for Immunization and Respiratory Diseases at CDC, introducing
Medical Officer Andrew T. Kroger, MD, MPH
Nurse Educator Donna L. Weaver, RN, MN
Submit a Question: Ask the Experts
You can email your question about vaccines or immunization to IAC. We will respond to your email inquiry.
Related Materials from IAC
IAC Express
Needle Tips
Vaccinate Adults
What's New - Q&As
Love the Question of the Week?
Receive it every week in your email box
>> Subscribe to IAC Express!
QUESTION: I've seen the recommendation stating air bubbles in manufacturer-filled syringes do not need to be expelled. Can you explain why those air bubbles can be injected but air bubbles in user-filled syringes must be expelled?
ANSWER: It is not wrong to expel the air from syringes filled by manufacturers, but typically it is such a small amount of air (0.2cc–0.3cc) that it is our opinion that it would not cause a problem. When the syringe is inverted during an injection, that small amount of air would typically just clear the medication from the needle. This is based on the recommendation that when the Z-track method is used for intramuscular injection of irritating medication (e.g., iron preparations), the guidance is to leave 0.2cc–0.3cc in the syringe to be sure that all of the medication leaves the needle and is not tracked back through subcutaneous tissue as the needle is withdrawn. While the Z-track injection technique is not recommended for vaccine administration, the Z-track method demonstrates the acceptability of leaving a very small amount of air in the syringe for intramuscular injections.

We do, however, recommend that when drawing vaccine from a vial into a regular syringe, the air be expelled because the amount of air drawn into the syringe may be larger than the amount in a manufacturer-filled syringe. Expelling the air is part of general medication guidelines for drawing medication into a syringe.
Question of the Week Archive
Immunization Action Coalition  •  2550 University Avenue West  •  Suite 415 North  •  Saint Paul, Minnesota  •  55114
tel 651-647-9009  •  fax 651-647-9131
This website is supported in part by a cooperative agreement from the National Center for Immunization and Respiratory Diseases (Grant No. 5U38IP000589) at the Centers for Disease Control and Prevention (CDC) in Atlanta, GA. The website content is the sole responsibility of IAC and does not necessarily represent the official views of CDC.