Will multiple injections overwhelm the immune system?
No. Every day our bodies come into contact with millions of germs, causing our immune system to work continuously to protect us. So exposure to a few antigens (parts of weak or dead viruses or bacteria) in vaccines is easily handled by our immune systems. In fact, our immune system needs to be challenged continually to stay vigorous. Modern biotechnology has actually reduced the number of antigens in today’s vaccines. For example, in 1980 the DTaP vaccine alone had 3017 antigens. Today, at the two-month visit there are a total of 34 antigens in all the recommended vaccines for that age – just 34 antigens, among the millions handled every day by our immune systems.
Canadian Immunization Guide. Evergreen edition. http://www.phac-aspc.gc.ca/publicat/cig-gci/index-eng.php (external link)
Your Child's Best Shot (3rd edition, p. 322) (external link)
Public Health Agency of Canada – Frequently Asked Questions (external link)
Immunization Communication Tool for Immunizers (ImmunizeBC, 2008) (external link)