What must be done to a reconstituted vaccine before administration?

The correct approach to preparing a reconstituted vaccine before administration is to swirl the vaccine gently. This action ensures that the vaccine is mixed uniformly without incorporating air bubbles, which can occur when shaking vigorously. Swirling allows the components to combine effectively and maintains the integrity of the vaccine, ensuring that the dose administered is consistent and effective.

Gentle rolling is often recommended for sensitive vaccines, but it does not provide the same thorough mixing as swirling. Meanwhile, letting the vaccine sit for an extended period or shaking vigorously could compromise the formulation, potentially leading to ineffective immunization or adverse reactions. Hence, gently swirling the vaccine strikes the best balance between maintaining the vaccine's stability and preparing it adequately for administration.