From site: https://www.historyofvaccines.org/conte ... accination
College of Physicians of Philadelphia
Last update 25 January 2018
Why aren’t all vaccines 100% effective?
Vaccines are designed to generate an immune response that will protect the vaccinated individual during future exposures to the disease. Individual immune systems, however, are different enough that in some cases, a person’s immune system will not generate an adequate response. As a result, he or she will not be effectively protected after immunization.
That said, the effectiveness of most vaccines is high. After receiving the second dose of the MMR vaccine (measles, mumps and rubella) or the standalone measles vaccine, 99.7% of vaccinated individuals are immune to measles. The inactivated polio vaccine offers 99% effectiveness after three doses. The varicella (chickenpox) vaccine is between 85% and 90% effective in preventing all varicella infections, but 100% effective in preventing moderate and severe chicken pox.
If a definition posted by the CDC implied 100% protecton, then clarification would be preferred, in my opinion.
From the CDC website now, on their Healthy Schools ‘Vaccine Basics’ page: https://www.cdc.gov/healthyschools/bam/ ... basics.htm
(Last reviewed June 28, 2019)
Vaccine: A preparation that is used to stimulate the body’s immune response against diseases. Vaccines are usually administered through needle injections, but some can be administered by mouth or sprayed into the nose.
Is the complaint about the recent change that the CDC was previously supposedly asserting that a vaccine was always 100% effective at preventing infection? It doesn’t read that way, based on the examples shown upstream.