Routine methods
Test-negative case-control design studies have been widely used to assess the effectiveness of many types of vaccines. In fact, the CDC published a study in the MMWR last month—a week before the COVID-19 study was set to publish—examining this year’s flu shot effectiveness with the same design. But the method gained a higher profile during the pandemic, with hundreds of studies using it to estimate COVID-19 vaccine effectiveness. Analyses have found that, like any observational study design, there are potential biases, but it’s generally considered to produce reliable estimates when those biases are controlled.
Andrew Nixon, spokesperson for the Department of Health and Human Services, which oversees the CDC, told the Post in a statement that “It’s routine for CDC leadership to review and flag concerns about MMWR papers, especially relating to their methodology, leading up to planned publication.”
Nixon said Bhattacharya, who is also head of the National Institutes of Health under Kennedy, was concerned by “the observational method used in the study to calculate vaccine effectiveness” and “wants to make sure that the paper uses the most appropriate methodology for such a study.” Nixon added that the agency’s “scientific team is working to address these concerns.”
Dan Jernigan, who headed CDC’s influenza division for six years and resigned last year in protest of Kennedy’s political interference at the agency, suggested to the Post that stalling the paper fits with Kennedy’s anti-vaccine agenda.
“The secretary has already taken steps to try and remove the availability of the vaccine from children and others, so if you’re putting out an MMWR that the vaccine is effective at preventing hospitalizations and medical care visits … that message is not in line with the direction you’ve been taking with the removal of the vaccine,” he said.