Federal health advisors predict four coronavirus vaccine trials backed by U.S. could fail

A top group advising U.. health officials predicted Tuesday that four late-stage coronavirus vaccine trials backed by the United States could fail to provide positive results.

The National Academies of Sciences, Engineering, and Medicine released a draft report that lays out a federal plan for distributing a coronavirus vaccine in the U.S. if and when one is approved for public use. The vaccine would be distributed in four phases with health-care workers and vulnerable Americans, such as the elderly and those with underlying health conditions, getting it first.

The group said it expects all volunteers participating in U.S. vaccine trials to get an approved vaccination early on regardless of its phased guidelines as "doing so is a typical standard of vaccine trial protocol." It said the administration's Operation Warp Speed expects to support up to seven 30,000-person phase three trials and it assumes four of them will fail. 

"Four of the trials will fail, and all subjects in those trials are offered access to an approved vaccine," the group wrote in the draft report. "Three of the trials will succeed, and, under a 1:1 ratio between members of treatment groups compared to the placebo group, 15,000 participants from each of those trials who were assigned to the placebo condition are offered and approved vaccine."

The U.S., as part of Operation Warp Speed, has already invested billions of dollars in six potential vaccines as of last month, including from drug companies Pfizer, Moderna and AstraZeneca, which have all entered phase three trials. 

Some vaccine candidates are being manufactured before regulatory approval. Because of the pandemic, U.S. health officials have been accelerating the development of vaccine candidates by investing in multiple stages of research even though doing so could be for naught if the vaccine ends up not being effective or safe.

According to a study published in the scientific journal Biostatistics in 2018, vaccines for infectious diseases have a 33.4% success rate of making through clinical trials.

This is a developing story. Please check back for updates.

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