Thimerosal is a preservative that is used in vaccines to prevent growth of harmful bacteria. While thimerosal has been in use in vaccines since the 1930s, some are concerned about the preservative because it contains mercury. For this reason, thimerosal is being used less often in newer vaccines, and has not been used in children's vaccines since 2001. Thimerosal, however, has never been banned by the Federal Government. Its use in vaccines has been limited by legislation in some states.
Shoulder pain is one of the most common types of vaccine-related injuries. But a new vaccine delivery method could make those injuries a thing of the past. That's because a new microneedle patch could, if widely adopted, eliminate the need for medical professionals to use needles when administering vaccines.