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.
There is some basis to to be concerned about thimerosol, even though the mercury it contains is of a different variety than the type that can accumulate in fish and cause harm in humans. According to the Centers for Disease Control and Prevention (CDC), the mercury contained in thimerosol does not remain in the body, and therefore is not likely to cause illness. This claim, however, has never been definitively proven. There is some research, notably by Burbacher et al., who found that ethylmercury from thimerosal accumulated readily in the brains of Macaque monkeys where it remained for a long period of time after breaking down to inorganic mercury,
Thimerosol is still used in some flu vaccines, however. And since the first shipment of flu vaccines for this season just shipped, so now may be a good time to weigh whether you prefer a flu vaccine that does not contain the preservative.
If you want to know if the flu shot available to you contains thimerosol, you can ask your pharmacist or the person administering the shot, or ask to look at the list of ingredients. The preservative isn't used in all flu shots, and you can request a different type of vaccine if you wish.
If you believe you or a loved one may have been injured by a flu shot - whether it contained thimerosol or not - you can get important perspective and learn your rights by talking to a lawyer with experience handling vaccine injury cases. While vaccines are important for public health and prevent disease, in some people they can cause adverse reactions.