Can flu vaccine be used if it was frozen?

No, flu vaccine should not be used if it was frozen. Freezing can damage the vaccine components and make it less effective or even harmful. The instructions provided with the vaccine usually specify the proper storage conditions, which typically involve refrigeration at a specific temperature range. It's important to follow these guidelines to ensure the safety and efficacy of the vaccine. If the vaccine has been frozen, it is best to discard it and obtain a new dose.