Dear Dr. Greene, my 16-year-old son has an immune disorder and needs a Hepatitis B shot. I’m concerned about the effects of mercury-containing vaccines on kids’ immune systems and brains. Are there any mercury-free Hep-B shots and mercury-free meningitis shots?

Your question comes in a lot. Many parents are concerned about mercury, which was used for years as a preservative in some vaccines. Fortunately, all of the vaccines routinely recommended for children come in versions without added thimerosal, the form of mercury used as a vaccine preservative. You can ask your doctor about the vaccine she or he uses, and share your preferences and concerns.

In general, single-dose vials, which supply one shot of vaccine in a small bottle, are far easier to make without adding a preservative than are the big vials used to vaccinate many people. However, single-dose vials require more resources to make, package, and store and are more costly, which is why the convenient multi-dose vials have been popular. We can’t give name brands of all the vaccines, because these are always changing, and different options are available to different doctors.

The standard vaccines given to children these days, which are all available in forms with no added mercury, include:

• Hepatitis B (also called Hep B)
• DTap (also called diptheria, tetanus, and acellular pertussis, or DPT or DTP)
• Hib (also called the meningitis shot, or Hemophilus influenzae type b, or H. flu)
• IPV (also called inactivated polio or polio -- this is not a live virus)
• PCV (also called the pneumococcal vaccine, ear infection vaccine, or meningitis vaccine)
• MMR (also called measles, mumps, and rubella - a live vaccine)
• Varicella (also called chickenpox)
• Flu (also called influenza)
• Hepatitis A (also called Hep A)
• Meningococcal (MCV4)