Vaccine Excipient Summary

Vaccine Excipient Summary

Excipients Included in U.S. Vaccines, by Vaccine

In addition to weakened or killed disease antigens (viruses or bacteria), vaccines contain very small amounts of other ingredients – excipients.

Some excipients are added to a vaccine for a specific purpose. These include:
Preservatives, to prevent contamination. For example, thimerosal.
Adjuvants, to help stimulate a stronger immune response. For example, aluminum salts.
Stabilizers, to keep the vaccine potent during transportation and storage. For example, sugars or gelatin.

Others are residual trace amounts of materials that were used during the manufacturing process and removed. These can include:
Cell culture materials, used to grow the vaccine antigens. For example, egg protein, various culture media.
Inactivating ingredients, used to kill viruses or inactivate toxins. For example, formaldehyde.
Antibiotics, used to prevent contamination by bacteria. For example, neomycin.

The following table lists substances, other than active ingredients (i.e., antigens), shown in the manufacturers’ package insert (PI) as being contained in the final formulation of each vaccine. Note: Substances used in the manufacture of a vaccine but not listed as contained in the final product (e.g., culture media) can be found in each PI, but are not shown on this table. Each PI, which can be found on the FDA’s website (see below) contains a description of that vaccine’s manufacturing process, including the amount and purpose of each substance. In most PIs, this information is found in Section 11: “Description.”

See Table Here

All information was extracted from manufacturers’ package inserts.
If in doubt about whether a PI has been updated since this table was prepared, check the FDA’s website at:

A table listing vaccine excipients and media by excipient is published by the Institute for Vaccine Safety
at Johns Hopkins University, and can be found at