Late on Monday in a series of tweets President
The hard truth: Science moves at its own pace. While COVID-19 vaccines are being developed at record speeds in hope of ending the pandemic, when they’re ready for prime time depends on a long list of research steps including how many study volunteers wind up getting the coronavirus — something scientists cannot control.
Here’s a look at the process:
HOW THE STUDIES WORK
And then another week after the second dose, key tracking begins: Counting anyone who experiences COVID-19 symptoms and tests positive for the virus as participants go about their daily routines, especially in hot spots.
Late-stage testing of other vaccine candidates is similar, varying slightly in the number of volunteers and timing.
HOW TO TELL SHOTS WORK
Every vaccine study is overseen by an independent “data and safety monitoring board,” or
Before a study is complete, only the
Those boards take sneak peeks at pre-determined times agreed to by the manufacturer and the
But the study isn’t stopping: To be sure of protection, it’s set to run until there are 164 infections. The more COVID-19 cases occur in the trial, the better idea scientists will have of just how protective the shots really are.
COULD THAT SNEAK PEEK HAVE COME EARLIER?
Pfizer’s initial plans called for evaluating when just 32 infections had been counted. But many scientists warned that was simply too small to draw conclusions about a vaccine needed by billions.
The higher number increases confidence in those still preliminary results, said Dr.
DON’T FORGET SAFETY
Safety is the top priority. Monitors also watch for unexpected or serious side effects. Earlier this fall, separate studies of vaccine candidates made by
But the FDA is requiring that companies track at least half of study volunteers for two months to look for side effects before asking the agency to review their vaccine. That’s about when side effects have cropped in studies of other vaccines.
WHAT HAPPENS THEN?
Companies are expected to seek permission for “emergency use” of their vaccines, rather than waiting to fully complete their studies and then seeking traditional approval.
The FDA’s scientific advisers will debate each company’s study findings in a public meeting before the agency decides.
Manufacturers already have begun stockpiling vaccine doses in anticipation of eventual approval, but the first shots will be in short supply and rationed. And the first people vaccinated will need to undergo extra safety tracking, as the government watches for rare side effects that might crop up when the shots are given to many more people than were in the research studies.
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