The efficacy of Pfizer and AstraZeneca’s COVID-19 vaccine turns negative against severe COVID-19 months after administration, according to a new study.
A single dose of Pfizer vaccine was pegged at -121 percent efficacy on day 84 and -85 percent efficacy on day 98.
One dose of the AstraZeneca vaccine was negative on day 70, and the second dose was negative on day 84, according to the report. paperwas published in the International Journal of Epidemiology.
Negative efficacy means that vaccinated people are more likely to experience symptoms than unvaccinated people.
The negative efficacy estimate in this study means that vaccinated people are more likely to experience severe COVID-19 than unvaccinated people.
Pfizer and AstraZeneca did not respond to requests for comment.
Researchers arrived at this estimate by analyzing the health records of about 12.9 million people in England, Scotland, Wales and Northern Ireland. The investigation period was from December 8, 2020 to June 30, 2021. This is one of the reasons we didn’t include boosters that weren’t available until late 2021.
Stephen Carr, a senior fellow at the Usher Institute at the University of Edinburgh, and other researchers theorized the negative estimates stemming from behavioral differences between vaccinated and unvaccinated populations. .
“We think the most likely explanation is that vaccinations made people believe they were protected and they changed their behavior to make them more likely to get infected.” “These behavioral changes should have been initially outweighed by the protection provided by the vaccine-stimulated immune response, but over time the protection weakened and the effects of the behavioral changes were diminished,” they wrote. may have become dominant.”
Researchers did not provide proof for the theory.
The group also said the protection they enjoy after recovering from COVID-19 may have played a role, one of many papers They conclude that innate immunity is superior to vaccination.
part of a growing trend
This study is the latest to estimate negative efficacy, although other studies have investigated efficacy against infections.
For example, Moderna researchers in a recent paper found that efficacy against infection with BA.2.12.1, BA.2, BA.4, and BA.5, all variants of the Omicron virus, became negative after several months. It has become. distortion.
Another paper analyzing efficacy against infection in children aged 5 to 11 estimated that the Pfizer vaccine turned negative after 18 or 20 weeks.
Qatari researchers looking at the efficacy of vaccines from Pfizer and Moderna estimated in June that efficacy had become negative over time.
Another paper published in May by U.S. scientists determined that the efficacy of Pfizer’s vaccine became negative after five months between the ages of 12 and 15.
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Zachary Stieber covers US and world news for The Epoch Times. He is based in Maryland.