A Trump administration appointee has delayed publication of a Centers for Disease Control and Prevention (CDC) report that demonstrates the benefits of the Covid vaccine, sparking concerns that the administration is undermining vaccine science through back-channel tactics.
The report, prepared by CDC scientists, found that the Covid vaccine reduced the likelihood of emergency room visits and hospitalisations for healthy adults last winter by approximately half, according to the Washington Post. Acting CDC director Jay Bhattacharya postponed the report's release due to concerns about its methodology.
Dr Fiona Havers, a former senior adviser on vaccine policy at the CDC who resigned last year in response to the administration's approach, described the delay as an escalation. “This is definitely an escalation of this administration’s undermining of CDC science,” she said. “The fact that they are now blocking this is extremely concerning.”
The research, covering September to December 2025, showed that vaccinated healthy adults had a 55% lower risk of Covid-related hospitalisation and a 50% lower risk of emergency or urgent care visits. The report was scheduled for publication on 19 March in the CDC's scientific journal but is now under review by Bhattacharya, who plans to meet with the scientists involved.
The methodology in question, known as “test-negative design”, has been used by the CDC for roughly two decades. Havers noted that a placebo-controlled trial would be unethical given the CDC's recommendation for vaccination. A separate report on flu vaccine effectiveness, using the same methodology, was published in the CDC's journal just a week earlier.
Health Secretary Robert F Kennedy Jr, a vocal critic of Covid vaccines, has previously called them the “deadliest vaccine ever made” and ordered the CDC not to recommend them for healthy pregnant women and children. A CDC spokesperson stated that leadership routinely reviews papers and that Bhattacharya had concerns about the observational method used, which the scientific team is addressing.
