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The surprising news from Pfizer that its COVID-19 vaccine could offer more protection than expected – an announcement right after a busy U.S. presidential election campaign – raises questions about exactly how the different vaccines will be marketed.
Pfizer Inc. and the maker of America’s other leading vaccine candidate, Moderna Inc., have been warning for weeks that the earliest possible time to get regulatory approval for wider use of their vaccines would be in late November. In Britain, AstraZeneca recently said it hopes to prove its own vaccine is effective by the end of the year.
Late Monday in a series of tweets, President Donald Trump accused the United States Food and Drug Administration and Pfizer of waiting until after the election to announce his positive news on vaccines for political reasons. Pfizer did not receive the data from the independent test monitors until Sunday, however. The FDA was not involved in Pfizer’s decision to announce its first results and made no announcement on its own initiative.
The hard truth: science evolves at its own pace. As COVID-19 vaccines are being developed at record speeds in hopes of ending the pandemic, when they are ready for prime time depends on a long list of research steps, including number of study volunteers who end up catching the coronavirus – something scientists can’t control.
Here’s an overview of the process:
HOW THE STUDIES WORK
Pfizer and its German partner BioNTech have recruited nearly 44,000 people for final testing of their vaccine. Neither the participants, nor their doctors, nor Pfizer know who gets the real vaccine and who gets vaccinated. They receive a second dose about three weeks after the first.
And then another week after the second dose, key tracking begins: counting all the people who have symptoms of COVID-19 and who test positive for the virus, as participants go about their daily activities, in especially in hot spots.
Advanced stage testing of other vaccine candidates is similar, varying slightly in the number of volunteers and the timing.
HOW TO SAY THE WORK OF SHOTS
Each vaccine study is overseen by an independent “Data and Safety Monitoring Board”, or DSMB. These councils include scientists and statisticians who have no connection with the vaccine manufacturers.
Before a study is completed, only the DSMB has the power to unlock the code that shows who got the real vaccine and who got the placebo, and recommend whether the injections are working well enough to stop testing prematurely.
These tips take a preview at predetermined times agreed upon by the manufacturer and the Food and Drug Administration. The first interim analysis for Pfizer took place on Sunday. The company said its data monitors have so far counted 94 infections – and among those early cases, the vaccine appeared to be 90% effective.
But the study does not stop: to be sure of protection, it is ready to go until there are 164 infections. The more cases of COVID-19 in the trial, the better the idea scientists will have of actual protection from the shots.
COULD THIS SNEAK PEEK COME EARLIER?
Pfizer’s original plans were to assess when only 32 infections had been counted. But many scientists have warned it is just too small to draw any conclusions about a vaccine billions need.
Pfizer said it reconsidered, returning to the FDA for permission to change the plan and do its first interim analysis when there were more cases. By the time Pfizer made the switch and caught up with a backlog of virus testing, the DSMB had 94 infections to analyze.
The higher number increases confidence in these still preliminary results, said Dr. Jesse Goodman, a former FDA vaccine scientist now at Georgetown University.
Moderna, AstraZeneca, and other companies not as far along in their final tests have all set slightly different times for when their data monitors will see how the shots perform.
DON’T FORGET SAFETY
Safety is the top priority. The monitors also monitor for unexpected or serious side effects. Earlier this fall, separate studies of vaccine candidates by AstraZeneca and Johnson & Johnson were temporarily halted after some participants had health concerns, delaying research until safety investigations allowed the two to resume.
Pfizer said on Monday that no serious safety concerns have so far emerged with its vaccine.
But the FDA is requiring companies to follow at least half of the study volunteers for two months to check for side effects before asking the agency to review their vaccine. It was around this time that the side effects appeared in studies of other vaccines.
Pfizer and Moderna both expect to meet this security target later in November.
WHAT HAPPENS THEN?
Companies are expected to seek approval for the “emergency use” of their vaccines, rather than waiting until their studies are completed and then seeking traditional approval.
FDA science advisers will discuss the results of each company’s study in a public meeting before the agency decides.
Manufacturers have already started stockpiling doses of the vaccine in anticipation of possible approval, but early vaccines will be scarce and rationed. And the first people vaccinated will need to undergo additional safety follow-up, as the government monitors for rare side effects that could occur when vaccines are given to many more people than in research studies.
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The Associated Press’s Department of Health and Science receives support from the Department of Science Education at the Howard Hughes Medical Institute. The AP is solely responsible for all content.
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