Thimerosal (Mercury) Law

Thimerosal, a chemical used to prevent contamination of multi-dose vials of vaccines, contains mercury. California’s Mercury-Free Act took effect on July 1, 2006. The Act prohibits administering mercury-containing vaccines to pregnant women or to children younger than three years of age. To meet the “mercury-free” standards in this law, most vaccines may not have more than 0.5 micrograms of mercury per 0.5 milliliters of vaccine dose. The mercury limit for influenza vaccine is 1 microgram per 0.5 milliliters. All routine childhood vaccines are available in formulations that meet the Mercury-Free Act.

For more information:

H1N1 Vaccine and Thimerosal Exemption  10/12/2009 – 9/30/2010
A letter from Dr. Mark Horton, Director of CDPH to interested parties about the use of H1N1 vaccine.

H1N1 Vaccine and Thimerosal Doctor Notification  10/12/2009 – 9/30/2010
A letter to California physicians about the use of H1N1 vaccine.

Complete Text of the California Law
The text of AB 2943.

Letter to California Physicians Administering Japanese Encephalitis Vaccine Inactivated (JE-VAX)  (Updated July 2009)         
A statement from Mark Horton, MD, State Public Health Officer, about using Japanese Encephalitis vaccine. 

Continued Use of Japanese Encephalitis Vaccine  (Updated July 2009)
A statement from Mark Horton, MD, State Public Health Officer, about using Japanese Encephalitis vaccine.

Frequently Asked Questions about California's Mercury Law
Information about the law, and mercury safety.

Physicians are Reminded to Order Thimerosal-free Flu Vaccine for Young Children  01/07
and Pregnant Women for the 2007-2008 Flu Season
A letter to California physicians about pre-booking influenza vaccine orders from Dr. Howard Backer, Chief of the Immunization Branch.

Vaccines (Other Than Influenza Vaccine) That Exceed the Legal Limit for Mercury Content 
The vaccines' full names, their manufacturers, formulations, and other information.