- metadata: - source: https://blogs.mercola.com/sites/vitalvotes/archive/2021/12/01/study-pfizer-covid19-vaccine-is-only-about-33-effective.aspx --- # Study: Pfizer COVID-19 Vaccine Is Only About 33% Effective > ## Excerpt > Study: Pfizer COVID-19 Vaccine Is Only About 33% Effective --- Researchers studying a cohort of 787 health care workers have found that the Pfizer COVID-19 vaccine not only loses its efficacy within a few months, but drops by a whopping 57% by six months after the second dose. Initial studies of BNT162b2 by Pfizer and BioNTech in 2020 estimated the efficacy of the biologic to prevent serious symptoms of COVID disease at 95 percent. A “real world” study of 4,000 health care workers conducted by the U.S. Centers for Disease Control and Prevention (CDC) earlier in 2021 suggested that the effectiveness of BNT162b2 was closer to 90 percent. Using the CDC’s numbers and based on the data gained from the new Italian study, the efficacy of the biologic is  estimated to be about 33 percent. The news is in stark contrast to Pfizer’s report that its shot has 95% efficacy, and to the CDC’s claim that it has at least 90% efficacy. The 33% is even lower than the 42% reported in a Pfizer/Kaiser Permanente study published in The Lancet. The decline affects all age groups, researchers said. Editor’s note: This blog has been revised to reflect additional research information. SOURCES: [The Vaccine Reaction November 29, 2021](https://thevaccinereaction.org/2021/11/efficacy-of-pfizers-covid-biologic-estimated-at-33-percent/#_edn1) [Medical News Today November 26, 2021](https://www.medicalnewstoday.com/articles/antibodies-from-covid-19-vaccine-may-reduce-by-57-after-6-months#57%-reduction) [STAT March 29, 2021](https://www.statnews.com/2021/03/29/real-world-study-by-cdc-shows-pfizer-and-moderna-vaccines-were-90-effective/#:~:text='Real%20world'%20study%20by%20CDC,Moderna%20vaccines%20were%2090%25%20effective&text=A%20new%20study%20suggests%20the,in%20a%20real%2Dworld%20setting.) [Pfizer November 18, 2020](https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-conclude-phase-3-study-covid-19-vaccine)