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FDA panel assesses challenges of Covid vaccine overhaul for fall


WASHINGTON — Researchers trying to design an updated coronavirus vaccine for use this fall should agree on a formula as early as June to meet that deadline, federal officials said Wednesday, even though some clinical trials are only doing to start.

The assessment took place during a day-long meeting of outside advisers from the Food and Drug Administration, who came together to strategize on what the national coronavirus vaccine policy should look like at the to come up. The session highlighted how the road ahead is strewn with uncertainties.

Among the most fundamental questions being debated: When would officials decide that existing vaccines aren’t working well enough? And if better vaccines are deemed necessary, when could clinical trials provide answers about suitable replacements?

The meeting marked a transition point for the Biden administration as it tries to craft a vaccine strategy for the rest of this year. Some federal health officials are convinced that existing vaccines need to be revamped to provide better protection than they currently do. They hope to have a revised version by the fall, amid fears the virus could resurface in force.

Modified vaccine doses could cost the federal government about $5 billion to $12 billion, a senior federal official said. Congress moved to roughly halve the administration’s new Covid budget request, which the official said may not leave enough to cover that cost.

At the same time, vaccine makers and federal researchers are scrambling to figure out what a revised vaccine should look like. A new study from the National Institutes of Health, for example, analyzes how Moderna’s vaccine works if it’s revised to target three different variants, alone or in combination. But it has only just started recruiting volunteers, with results expected this summer.

Robert Johnson, director of an infectious disease division within the Department of Health and Human Services, told the panel that even once regulators decide on a reconfigured vaccine, manufacturers would need several months to produce doses.

“If you’re not on your way to that clinical trial in early May, it’s very difficult to collectively have enough products among manufacturers to meet that demand” by the fall, he said. Dr Peter Marks, who oversees vaccine regulation at the FDA, also described the timeline as very compressed, saying regulators may have to agree on a new vaccine formula by May or June if they want to switch from existing formulas.

The ongoing trials are too small to provide efficacy data of the type that has led to licensing of existing vaccines. But they could yield enough data for federal health officials to determine whether a reconfigured vaccine will create a stronger or longer-lasting immune response — a metric used to infer efficacy.

Expert after expert at the meeting, he described the amount of guesswork involved in this effort. No one knows which variant of the virus will dominate in the fall, as federal authorities consider another outbreak very likely. Chances are that before that, another variant like Omicron will emerge and reshape the picture of the coronavirus in completely unexpected ways. “Not likely, but it’s there,” Dr. Marks said of that possibility.

Trevor Bedford, biostatistician at Fred Hutchinson Cancer Research Center, said the coronavirus mutated at several times the rate of the flu virus, for which vaccines are redesigned every year. Although that pace may be slowing, the plasticity of the virus indicates that it “is likely to continue to evolve”, he said.

How exactly this will turn out is anyone’s guess. “There is no guarantee that each emerging variant will serve as the basis for the next variant,” warned Dr. Michael Nelson, an immunologist at the University of Virginia School of Medicine.

Meanwhile, federal officials and their outside advisers continue to debate what the threshold is for determining that existing vaccines aren’t doing a good enough job. Dr Marks said the consensus of the committee appeared to be that Covid vaccines should prevent serious illness, not necessarily infection or mild illness.

The question was particularly relevant because last week the FDA authorized a second recall for Americans 50 and older, along with a few others. But the CDC director bluntly recommended these injections only to people 65 and older and anyone 50 to 64 with serious underlying health conditions.

Some immunologists and vaccine experts have said the FDA does not have the data needed to authorize a second booster, while other health officials have argued that people should be given the option of another vaccine.

Dr. James EK Hildreth, president of Meharry Medical College in Tennessee and a committee member, asked Dr. Marks why he didn’t seek the panel’s input before deciding whether to allow a second recall.

Dr. Marks said the FDA does not plan to offer a second recall as “a major expansion or a major change.” Jerry Weir, another senior agency official, said the FDA plans to ask the advisory group to review any reconfigurations of existing vaccines before moving forward with emergency clearance.

Sharon Alroy-Preis, director of public health services for Israel’s Health Ministry, told the panel that administering a second booster to people 60 and older earlier this year had saved lives. The Israeli submission appeared to support the FDA’s decision.

But European Union regulators concluded on Wednesday that it was “too early” to give second booster shots to the general population, but reasonable to offer them to people aged 80 and over.

Senior CDC official Dr. Amanda Cohn said her agency’s data shows that existing vaccines are more than 80% effective in preventing hospitalization of Americans without immune deficiencies – including the elderly and those with chronic diseases. She suggested that post-infection Covid treatments might be more effective than additional shots of the vaccine in protecting Americans from serious illness.

Dr Christopher Murray, a professor at the University of Washington whose institute has modeled pandemic trends, predicted that antiviral treatments like the pills recently developed by Pfizer will reduce death rates even if a new variant as infectious as ‘Omicron and as deadly as Delta emerges.

Dr. John Beigel, director of clinical research at the NIH, described his agency’s research comparing how Moderna’s existing vaccine works versus modified versions targeting known variants, alone and in combination.

As a first step, the researchers hope to quickly recruit 600 volunteers who have already been vaccinated and received a booster. Some will receive the existing vaccine. Others will receive experimental vaccines targeting only the Omicron variant along with three other variants: Omicron plus the Beta variant, the Delta variant, and the prototype virus that appeared first in the pandemic.

In an interview on Tuesday, Dr. Beigel said existing vaccines may yet prove to be the best. He said he hopes his trial results could be ready by mid-summer, although some federal officials are hoping sooner.

Deciding on the next step, he told the panel, “is going to be difficult.”

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