CDC director delays COVID-19 vaccine effectiveness report over methodological concerns

Acting Director of the Centers for Disease Control and Prevention (CDC) Jay Bhattacharya has reportedly delayed the publication of a government report detailing the benefits of COVID-19 vaccines, citing concerns over the study’s methodology.

The report in question examined the effectiveness of COVID-19 vaccinations among healthy adults during the previous winter season. According to two scientists familiar with the decision, the study focused specifically on the rates at which vaccines reduced hospitalizations and emergency department visits. The Washington Post first reported the development on Thursday.

Controversial methodology: Test-negative design

The methodology employed by the CDC for the report has been a long-standing tool used by the agency to determine vaccine effectiveness against respiratory viruses. The findings were originally scheduled for publication in the Morbidity and Mortality Weekly Report (MMWR), the CDC’s primary scientific digest.

The “test-negative design” method used in the report relies on examining individuals who were ill enough to seek medical assistance and undergo testing. Under this framework, researchers create a dataset by comparing the vaccination rates of individuals who tested positive with those who tested negative. This specific methodology was previously utilized in a 2021 COVID-19 vaccine effectiveness study published by the New England Journal of Medicine.

HHS confirms review process

Andrew Nixon, a spokesperson for the US Department of Health and Human Services (HHS), said in a statement that the delay is a routine part of the process in which CDC leadership reviews MMWR articles prior to scheduled publication and flags methodological concerns.

Nixon stated that Bhattacharya expressed reservations regarding the “observational method” used to calculate vaccine effectiveness in the study, and that the scientific team is currently working to address those concerns. He added that Bhattacharya intends for the article to utilize the most appropriate methodology for this type of research.

The decision to delay the report follows the Monday release of an updated charter by HHS Secretary Robert F. Kennedy Jr. for the Advisory Committee on Immunization Practices (ACIP).

The previous committee had voted to move away from a general recommendation of COVID-19 vaccines for everyone aged 6 months and older, suggesting instead that such decisions be made on an “individual basis.” However, a federal judge subsequently issued a ruling that effectively nullified the authority of the committee members selected by the secretary.

In a separate development, Vinay Prasad, a former Food and Drug Administration (FDA) regulator, has reportedly introduced new restrictions on the approval of COVID-19 vaccines manufactured by Novavax and Moderna.

According to a memo sent to FDA officials and obtained by the Post, Prasad stated that vaccine approval guidelines would be tightened following the deaths of 10 children after receiving COVID-19 vaccinations, attributing the fatalities to the vaccine. The move is expected to further intensify the ongoing debate surrounding vaccine approval processes.