Which of the following is the first step in the reconstitution of a vaccine?

The first step in the reconstitution of a vaccine is to check the labels for the expiration date and lot number. This step is crucial for ensuring patient safety, as using vaccines that are expired or from a recalled lot can lead to ineffective immunization or adverse reactions. Verifying the expiration date helps to confirm that the vaccine is still potent, while checking the lot number allows for tracking and accountability in the event of any vaccine-related issues. This fundamental step ensures that the healthcare provider is administering the correct and safe product.

Following this step, other actions, such as checking the volume of diluent needed and eventually mixing the vaccine with the diluent, take place. However, it is essential to prioritize the verification of the vaccine's integrity and safety before proceeding with reconstitution.