CDC changed definition of ‘vaccine’ and ‘vaccination’

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“CDC Changed Definition of ‘Vaccine’ and ‘Vaccination’

CDC officials frequently have referred to vaccines as “immunizations.”160 But in 2021, the CDC suddenly changed its definition of “vaccine” from “a product that stimulates a person’s immune system to produce immunity to a specific disease” to “a preparation that is used to stimulate the body’s immune response against diseases.”161

The Merriam Webster Dictionary also changed its definition of “vaccine” to eliminate the concept that a vaccine stimulates “immunity” and replaced it with the concept that vaccines create an “immune response.”162

Up until now, the words “vaccine” and “vaccination” have been synonymous with creating “artificial immunity” in humans and animals.163

The rewriting of that definition to admit that vaccines cannot be presumed to confer immunity — only modify the person’s immune response — is stunning because mandatory vaccination laws historically have been based on the common belief that all infants and children must get vaccinated to create “herd immunity” and prevent the transmission of contagious diseases within a community.164,165

If the definition of “vaccine” and “vaccination” no longer includes the concept of immunity,166 then the definitions of vaccine “efficacy” and “effectiveness” have been forever changed as well.167,168

Public Misled That Shots Prevent Infection and Transmission

To obtain the EUA in late 2020, Pfizer published clinical trial data involving about 43,000 participants over age 16, with more than 21,000 of them injected with the company’s experimental mRNA COVID vaccine. Pfizer said the data showed that two doses of the vaccine achieved a 95% efficacy for preventing severe COVID disease.169,170

Most mainstream media reports publicizing the Pfizer clinical trial results misled the public into believing that a 95 percent “efficacy” rate meant the vaccine reliably prevented SARS-CoV-2 infection.171 Americans obeying mask mandates put into place before the vaccine was released, assumed that they would be able to ditch the mask and stop social distancing once they got vaccinated.172

But in early 2021 when CDC officials did not back away from mask mandates for vaccinated persons, people started suspecting something was wrong about that assumption. Fully vaccinated people were told to keep the masks on and socially distance like unvaccinated people.173

The logical question was: Why do fully vaccinated people have to worry about getting infected or infecting other people?

The answer to that question became obvious when study after study published in the medical literature since December 2020 showed that two or three doses of Pfizer’s mRNA COVID vaccine do not reliably prevent symptomatic or asymptomatic infection and transmission of SARS-CoV-2 virus, and the vaccine has a very short shelf life for protection against COVID disease, waning within a few months of vaccination.174,175,176

While that reality sets in, studies are revealing that naturally acquired immunity from the new coronavirus infection is broad and long-lasting,177,178,179,180,181 perhaps two years or more.182


160 CDC. Five Important Reasons to Vaccinate Your Child. February 2015.

161 Camero K. Why did CDC change its definition for ‘vaccine’? Agency explains move as skeptics lurk. Miami Herald Sept 27, 2021.

162 Kochi S. Fact check: Missing context in claim that Merriam-Webster changed ‘vaccine’ definition. USA Today Nov. 30, 2021.

163 Clem AS. Fundamentals of Vaccine Immunology. J Glob Infect Dis 2011; 3(1): 73-78.

164 Anderson RM, May RM. Vaccination and herd immunity to infectious diseases. Nature 1985; 318: 323-329.

165 Drew L. The case for mandatory vaccination. Nature Nov. 27, 2019.

166 CDC. Definition of Vaccination: “The Act of introducing a vaccine into the body to produce immunity to a specific disease.” Immunization: The Basics. May 16, 2018 (Archived).

167 Knight-Jones TJD, Edmond K et al. Veterinary and human vaccine evaluation methods. Proc Biol Sci 2014; 281(1784).

168 Caddy SL. Coronavirus: few vaccines prevent infection – here’s why that’s not a problem. The Conversation Jan. 5, 2021.

169 Pfizer Inc., BioNTech SE. Pfizer and BioNTech to Submit Emergency Use Authorization Request Today to the U.S. FDA for COVID-19 Vaccine. Nov. 20, 2020.

170 Polack FP, Thomas SJ, Kitchin N et al. Safety and Efficacy of the BNT162B2 mRNA COVID-19 Vaccine. N Engl J Med Dec. 10, 2020.

171 Lovelace Jr B. Pfizer says final data analysis shows Covid vaccine is 95% effective, plans to submit to FDA in days. CNBC Nov. 18, 2020.

172 Nissen N. Now that we have 2 vaccines, will life return to normal? ABC News Dec. 19, 2020.

173 Rouen R. Fact Check: CDC recommends masks in most cases even after COVID-19 vaccine. USA Today Apr. 22, 2021

174 Singanayagam A, Hakki S, Dunning J et al. Community transmission and viral load kinetics of the SARS-CoV-2 delta (B.1.617.2) variant in vaccinated and unvaccinated individuals in the UK: a prospective, longitudinal, cohort study. Lancet Oct. 29, 2021.

175 Levin EG, Lustig Y, Cohen C et al. Waning Immune Humoral Response to BNT162b2 Covid-19 Vaccine over 6 Months. N Engl J Med 2021; 385

176 Ferdinands JM, Rao , Dixon BE et al. Waning 2-Dose and 3-Dose Effectiveness of mRNA Vaccines Against COVID-19-Associated Emergency Department and Urgent Care Encounters and Hospitalizations Among Adults During Periods of Delta and Omicron Variant Predominance – VISION Network, 10 States, Aug MMWR Feb. 11, 2022; 71.

177 Kojima N, Klausner JD. Protective immunity after recovery from SARS-CoV-2 Infection. The Lancet 2021; 22(1): 12-14.

178 Abu-Raddad LJ, Bertollini R. Severity of SARS-CoV-2 Reinfection as Compared with Primary Infections. N Eng J Med 2021; 385: 2487-2489.

179 Gazit S, Shlezinger R, Perez G et al. Comparing SARS-CoV-2 natural immunity to vaccine induced immunity: reinfections versus breakthrough infections. medRxiv Aug. 25, 2021.

180 Altarwneh HN, Hasan MR, Ayoub HH et al. Protection against the Omicron Variant from Previous SARS-CoV-2 Infection. N Engl J Med Feb. 9, 2022.

181 Balachandran H, Phetsouphanh C et al. Maintenance of broad neutralizing antibodies and memory B cells 1 year post-infection is predicted by SARS-CoV-2 specific CD4+ T cell responses. Cell Rep 2022; 38(6).

182 Alejo JL, Mitchell J, Chang A et al. Prevalence and Durability of SARS-CoV-2 Antibodies Among Unvaccinated US Adults by History of COVID-19. JAMA Feb. 3, 2022.

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