What is the appropriate needle size and length for administering varicella vaccine to an adult woman who weighs 175 lbs?

The best choice for administering the varicella vaccine to an adult woman who weighs 175 lbs is a 25 gauge, 5/8 inch needle. The varicella vaccine is typically administered subcutaneously, and for this route of administration in adults, a 5/8 inch needle is suitable. The gauge of the needle, which refers to the thickness, is also important; a 25 gauge needle is thin enough to minimize discomfort while still allowing effective delivery of the vaccine.

Using a 5/8 inch needle helps ensure that the vaccine is injected into the subcutaneous tissue rather than deeper muscle, which is preferred for live vaccines like varicella. This combination is consistent with the vaccination guidelines that specify using a shorter needle for subcutaneous injections in adults, ensuring both effective delivery and patient comfort.