News from the FDA/CDC

CDC panel takes on COVID vaccine rollout, risks, and side effects


Federal advisers who will help determine which Americans get the first COVID vaccines took an in-depth look Oct. 30 at the challenges they face in selecting priority groups.

The Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention (CDC) will face two key decisions once a COVID vaccine wins clearance from the US Food and Drug Administration (FDA).

ACIP will need to decide whether to recommend its use in adults (the age group in which vaccines are currently being tested). The group will also need to offer direction on which groups should get priority in vaccine allocation, inasmuch as early supplies will not be sufficient to vaccinate everyone.

At the Oct. 30 meeting, CDC’s Kathleen Dooling, MD, MPH, suggested that ACIP plan on tackling these issues as two separate questions when it comes time to weigh in on an approved vaccine. Although there was no formal vote among ACIP members at the meeting, Dooling’s proposal for tackling a future recommendation in a two-part fashion drew positive feedback.

ACIP member Katherine A. Poehling, MD, MPH, suggested that the panel and CDC be ready to reexamine the situation frequently regarding COVID vaccination. “Perhaps we could think about reviewing data on a monthly basis and updating the recommendation, so that we can account for the concerns and balance both the benefits and the [potential] harm,” Poehling said.

Dooling agreed. “Both the vaccine recommendation and allocation will be revisited in what is a very dynamic situation,” Dooling replied to Poehling. “So all new evidence will be brought to ACIP, and certainly the allocation as vaccine distribution proceeds will need to be adjusted accordingly.”

Ethics and limited evidence

During the meeting, ACIP members repeatedly expressed discomfort with the prospect of having to weigh in on widespread use of COVID vaccines on the basis of limited evidence.

Within months, FDA may opt for a special clearance, known as an emergency use authorization (EUA), for one or more of the experimental COVID vaccines now in advanced testing. Many of FDA’s past EUA clearances were granted for test kits. For those EUA approvals, the agency considered risks of false results but not longer-term, direct harm to patients from these products.

With a COVID vaccine, there will be strong pressure to distribute doses as quickly as possible with the hope of curbing the pandemic, which has already led to more than 229,000 deaths in the United States alone and has disrupted lives and economies around the world. But questions will persist about the possibility of serious complications from these vaccines, ACIP members noted.

“My personal struggle is the ethical side and how to balance these two,” said ACIP member Robert L. Atmar, MD, of Baylor College of Medicine, Houston, Texas, who noted that he expects his fellow panelists to share this concern.

Currently, four experimental COVID vaccines likely to be used in the United States have advanced to phase 3 testing. Pfizer Inc and BioNtech have enrolled more than 42,000 participants in a test of their candidate, BNT162b2 vaccine, and rival Moderna has enrolled about 30,000 participants in a test of its mRNA-1273 vaccine, CDC staff said.

The other two advanced COVID vaccine candidates have overcome recent hurdles. AstraZeneca Plc on Oct. 23 announced that FDA had removed a hold on the testing of its AZD1222 vaccine candidate; the trial will enroll approximately 30,000 people. Johnson & Johnson’s Janssen unit also announced that day the lifting of a safety pause for its Ad26.COV2.S vaccine; the phase 3 trial for that vaccine will enroll approximately 60,000 volunteers. Federal agencies, states, and territories have developed plans for future distribution of COVID vaccines, CDC staff said in briefing materials for today’s ACIP meeting.

Several ACIP members raised many of the same concerns that members of an FDA advisory committee raised at a meeting earlier in October. ACIP and FDA advisers honed in on the FDA’s decision to set a median follow-up duration of 2 months in phase 3 trials in connection with expected EUA applications for COVID-19 vaccines.

“I struggle with following people for 2 months after their second vaccination as a time point to start making final decisions about safety,” said ACIP member Sharon E. Frey, MD, a professor at St. Louis University School of Medicine, St. Louis, Missouri. “I just want to put that out there.”


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