Two new pieces of information have become available that reinforce the likelihood of a COVID-19 vaccine before year’s end. First, in a conversation I had with Dr. Peter Marks, Director of the Center for Biologics Evaluation and Research (CBER), in a public forum last week, Dr. Marks clarified that the agency would be requesting two months of follow-up safety data on the efficacy cohort rather than the limited safety cohort of 3,000 required subjects. The media had earlier suggested that such a requirement would delay authorization of a vaccine until 2021 or, at the earliest, late December. But recently, according to the New York Times, and as we expected, Pfizer has announced the likelihood of filing for an Emergency Use Application for their vaccine in mid-November.
In an earlier communication, we noted that Pfizer had announced the completion of enrollment of over 30,000 patients in an efficacy cohort enrolled at over 120 trial sites in 4 countries, including the United States, each of whom had received two doses. Of these patients, Pfizer had earlier announced that approximately 11,000 had completed the two dose regimen by September 10. Those subjects would have completed a two-month follow-up by November 10. These new data suggest that the vaccine may be remarkably effective in that first 11,000 subject cohort. To that end, CBER had previously stated that approval would be based on a minimum efficacy of 50% over placebo with a lower confidence or statistical limit of 30%. If that degree of efficacy is achieved in an 11,000 subject cohort, either the baseline incidence in the placebo group would be very high and/or the vaccine more effective than anticipated. For instance, our earlier announcement had suggested that achieving that result in 30,000 subjects would require a baseline incidence in the control group of around 0.12% and might, as reported by the media, delay approval until December. But the November date and Dr. Marks’ comment suggest that the 11,000 cohort will be sufficient as an efficacy cohort. We also note that former Vice President Biden revised his view as to whether he would personally take it, rather than couching his willingness on an endorsement by scientists independent of the President.
We remain cautious. If Pfizer receives an Emergency Use Authorization, the available doses in November or December will be limited and likely reserved for high risk individuals such as health care workers, nursing home residents or others who live in close contact communities, and the elderly. Further information may become available during the October 22 meeting of the agency’s vaccine advisory panel. Dr. Marks further noted to me that, if data become available on a specific vaccine before the panel meets, he would likely extend the panel meeting to additional days or reconvene the panel shortly after the data are received.
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