The U.S. Centers for Disease Control and Prevention (CDC) altered its definition of COVID-19 cases among the vaccinated, leading to a lower number of cases classified as a breakthrough, according to documents obtained by The Epoch Times.
The CDC in early 2021 defined the post-vaccination cases as people testing positive seven or more days after receipt of a primary vaccination series, according to one of the documents.
The definition was changed on Feb. 2, 2021, to only include cases detected at least 14 days after a primary series, another document shows.
“We have revised the case definition,” Dr. Marc Fisher, the lead of the CDC’s Vaccine Breakthrough Case Investigation Team, wrote to colleagues at the time.
The rationale for the change was redacted.
A CDC spokesperson defended the altered definition.
“CDC made the change to the definition of a breakthrough infection time period due to the most current data that showed that the 14-day period was required for an effective antibody response to the vaccines,” Scott Pauley, the spokesman, told The Epoch Times in an email.
“That, in combination with the data showing that many cases of COVID-19 were incubating for up to two weeks before becoming symptomatic, required the change to refine the time period to eliminate cases where exposure happened before the vaccination response would be effective,” Mr. Pauley added.
Dr. Harvey Risch, professor emeritus of epidemiology at the Yale School of Public Health, said there was “no cogent rationale” for excluding early cases and other events among the vaccinated, whether they occurred within seven days or 14 days.
“With either of these delays, CDC addressed what is the theoretical best that the vaccination could achieve. If the vaccines don’t work for the first 7 or 14 days or increase risk of getting Covid-19 during that period, that is part of what happens when they are deployed in a population,” Dr. Risch told The Epoch Times via email.
Dr. Jay Bhattacharya, professor health policy at Stanford University, said that the CDC should have been focused on advising people that they weren’t as protected immediately after vaccination.
