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WASHINGTON – The suspension of a large study of the Covid-19 vaccine on a disease in a single participant shows that there will be “no compromises” on safety in the race to develop the vaccine, the head of the National Institutes of Health said Wednesday. to Congress.
AstraZeneca has suspended studies of its vaccine candidate in the US and other countries while it investigates whether a British volunteer’s illness is a side effect or a coincidence.
“This should be reassuring,” NIH Director Dr. Francis Collins told a Senate committee. “When we say that we are going to focus on security first and make no concessions, here is Exhibit A of how that is happening in practice.”
Scientists have been scrambling to develop a coronavirus vaccine since the outbreak began, and the US has launched the world’s largest studies – end-stage testing of three major candidates, with three more trials to be conducted soon. they will recruit 30,000 test subjects each. .
Public health experts are concerned that President Donald Trump will pressure the Food and Drug Administration to approve a vaccine before it is proven safe and effective, a concern echoed by senator after senator on Wednesday.
“When it comes to a Covid-19 vaccine, we cannot allow President Trump to repeat his alarming pattern of putting politics before science and public health,” said Sen. Patty Murray of Washington, the committee’s highest-ranking Democrat. .
The United States has invested billions of dollars in efforts to rapidly develop multiple Covid-19 vaccines. But public fear that a vaccine is unsafe or ineffective could be disastrous and deflect the effort to vaccinate millions of Americans.
Collins said the public must understand the process behind saying when a candidate vaccine is ready for widespread use, one that by design keeps manufacturers and politicians in the dark until the evidence stabilizes.
Roughly 150 Covid-19 infections in a study of 30,000 people should be enough to know if that candidate is really working, and an independent group of experts, not the FDA, can do the tally.
Who supervises the studies?
Each trial of a vaccine is overseen by a “data and safety monitoring board” or DSMB. These boards include scientists and statisticians who are experts in their fields but have no ties to the government or vaccine manufacturers.
Top priority: keep an eye out for safety concerns, like the one prompted by a DSMB in Britain to stop AstraZeneca vaccines and alert its American counterpart.
But this is the group that will also decide when each vaccine is ready for evaluation by regulators.
In each study of 30,000 people, about half of the participants get the real vaccine and the other half get bogus shots, and neither they nor their doctors know which is which. Only the DSMB has the power to unlock the code of who was shot what and see how the volunteers are doing before the study ends.
The FDA can’t even begin considering a vaccine approval until the DSMB says the data is good enough for that debate, Collins stressed. Once that happens, the FDA is committed to bringing each candidate before a public vaccine advisory committee.
Doing the math
The FDA has already told manufacturers that it will not consider any vaccine less than 50 percent effective.
Let’s say a vaccine trial records that 150 volunteers got sick. The DSMB finds that 100 had received dummy injections and 50 had received the real vaccine. The panel of experts could decide that it is a promising enough vaccine to stop the study early so that the FDA can debate its merits, even before getting the final results from the 30,000 volunteers, said Dr. Larry Corey of the Institute. Cancer Research Officer Fred Hutchinson, who oversees the US government’s vaccine studies.
On the other hand, if equal amounts of the vaccine and placebo groups are infected, the DSMB could declare a vaccine useless, he told The Associated Press. These panels can also calculate infections even before that threshold of 150 is reached, at set time points in each study.
“If your vaccine is at least 50 percent effective, you know because you will see a huge bias” from infections, the NIH’s Collins told the Senate health, education, labor and pensions committee. “Count those events and know if it worked or not.”
Unlikely responses before the US elections
Getting the math right before November, as Trump promised, is “incredibly unlikely,” Corey said.
Collins expressed “cautious optimism” that one of the vaccines being tested will work before the end of the year, but cautioned: “Certainly trying to predict whether it occurs in a particular week before or after a particular date early November is much more anything any scientist can tell you right now. “
And even if a study has a large enough series of infections to prove the question of efficacy, the DSMB must also be sure that there is sufficient evidence for safety before opening the books to the FDA. Generally, the FDA requires safety data from at least 3,000 people, Surgeon General Jerome Adams told the Senate panel.
This process is not new: Phase 3 studies of vaccines and therapies are always done this way, although rarely in such bright light.
Failing a study is not so rare
It’s not uncommon for pauses in the investigation to investigate whether or not an unexpected health complaint is really vaccine-related, Collins told senators concerned about what the suspension of AstraZeneca means for the nation’s year-end goal.
“The reason we’re not investing in one, but six different vaccines is because of the expectation that not all of them will work,” Collins said.
AstraZeneca did not elaborate on the disease, but Collins said it was a “spinal cord problem.” Studies in earlier stages had not revealed any serious side effects, but that’s a key reason for increasingly extensive research phases: expanding the search for reactions.
Final testing of two other vaccines continues, one created by the NIH and manufactured by Moderna Inc., the other by Pfizer and Germany’s BioNTech. Those two vaccines work differently than AstraZeneca’s, which was developed by the University of Oxford, and the studies have already recruited about two-thirds of the volunteers needed.
Several candidate vaccines made by Chinese companies are in the final stages of testing in several countries, but with fewer volunteers. Most health authorities are skeptical about Russia’s claim of a vaccine’s success, which has test results from only a few dozen people. AP
