Latex

Latex is a product of the rubber tree. It is processed and used in various products, including some that come in contact with vaccines.
Latex may be present in syringe plungers, vial stoppers, or in the tip caps on prefilled syringes.
Some people develop sensitivity to latex, particularly if they have had significant cumulative latex exposure, such as from repeated surgeries early in life or employment in the healthcare industry.
The most common type of latex sensitivity is contact-type allergy; however, on rare occasions, severe (anaphylactic) allergy occurs.
People with a history of anaphylactic reactions to latex should not be given vaccines that have been in contact with natural rubber or latex, either in the vial or in the syringe, due to the risk of a potential allergic reaction.
Not all stoppers in vaccine vials contain latex. Some manufacturers have switched to synthetic rubber-like materials that do not contain rubber latex or dry natural rubber.
The best approach is to do the Vaccine Calculator and then check the package insert, which will indicate if the packaging contains latex.
Note that prefilled syringes used for vaccines could contain natural rubber in the plunger, in the needle cover, or in the tip cap. This information is also supplied in the package insert.