A federal advisory committee on Tuesday discussed but did not formally recommend who should get the initial doses of a limited COVID-19 vaccine when it's available.
The Advisory Committee on Immunization Practices (ACIP), which advises the Centers for Disease Control and Prevention (CDC), was expected to vote on prioritization but is now waiting until more data becomes available.
During the committee's meeting, ACIP Chairman Jose Romero said a subgroup will review Phase 3 clinical trial data once companies make it available, and then present recommendations to the full committee.
When the Food and Drug Administration announces a vaccine authorization, the committee will hold an emergency meeting and vote on recommendations for use, Romero said.
The next scheduled committee meeting is in late October.
There are three vaccine candidates undergoing late stage clinical trials in the U.S., manufactured by Pfizer, Moderna and AstraZeneca. Both Pfizer and Moderna executives have said they hope to have safety data available by November; the AstraZeneca trial is on hold in the U.S.
ACIP members discussed how they would prioritize different groups, but much depends on the characteristics of whatever vaccine is approved. Without knowing which vaccine has been approved, they can't know who it would be most effective for, who can reasonably access it and how they can maintain physical distancing if people line up to receive it.
Storage requirements also differ for each vaccine.
The consensus among experts is that any COVID-19 vaccine distribution will require a phased approach, especially as the first doses will be extremely limited.
The expectation is that the first doses would go to front-line health workers, and then subsequent "Phase 1b" would target essential workers, people with high risk medical conditions and those 65 and older.
But there's potential overlap between the groups, and ACIP members discussed whether they would need to make a ranked distinction in the second phase of initial dosing.
A separate set of guidelines developed by the National Academies of Sciences, Engineering, and Medicine also recommend a phased approach, beginning with front-line health workers, first responders and people at serious risk for infection.
The CDC told state health officials to be ready to begin vaccination campaigns in November, and a federal distribution framework aims to have vaccines sent to states within 24 hours of authorization.