内容摘要：Animals offer the tantalizing promise of a ready-made supply. After decades of failed attempts, companies including Revivicor,

Animals offer the tantalizing promise of a ready-made supply. After decades of failed attempts, companies including Revivicor,

For years, federal health officials have told most Americans to expect annual updates to COVID-19 vaccines, similar to the annual flu shot. Just like with flu vaccines, until now the FDA has approved updated COVID shots so long as they show as much immune protection as the previous year’s version.But FDA’s new guidance appears to be the end of that approach, according to Prasad and

, who co-authored the journal paper and joined the FDA webcast.Prasad and Makary criticized the U.S.’s “one-size-fits-all,” contrasting it with some European countries that recommend boosters based on age, risk and other factors.Prasad said the FDA will ask all manufacturers to do new clinical trials in healthy people ages 50 to 64, randomly assigning them to get a vaccine or a placebo and tracking outcomes with special attention to severe disease, hospitalization or death. Companies might need to repeat that requirement for future vaccine approvals if there’s a large virus mutation rather than the past year’s incremental evolution. Companies are also free to test their vaccines for approval in younger adults and children, Prasad said, adding “this is a free country.”

Since becoming the nation’s top health official in February, Kennedy has filled the FDA and other health agencies with outspoken critics of the government’s handling of COVID shots, including Makary and Prasad. Under federal procedures, the FDA releases new guidance in draft form and allows the public to comment before finalizing its plans. The publication of Tuesday’s policy in a medical journal is highly unusual and could run afoul of federal procedures, according to FDA experts.Health experts say there are legitimate questions about how much everyone still benefits from yearly COVID vaccination or whether they should be recommended only for people at increased risk.

In June, an influential panel of advisers to the CDC is set to debate which vaccines should be recommended to which groups.

The FDA’s announcement appears to usurp that advisory panel’s job, Offit said. He added that CDC studies have made clear that booster doses do offer protection against mild to moderate illness for four to six months after the shot even in healthy people.First, what pig to use: Some have up to 10 genetic changes but Montgomery is betting one is enough — removal of a single porcine gene that triggers an immediate immune attack.

While the pigs are housed in a germ-free facility, researchers performed extra testing for any hidden infection. Everyone in the operating room must have certain vaccinations and undergo blood tests of their own.Surgery over, doctors wheeled Miller’s body into the same ICU room where five years earlier Montgomery had recovered from his heart transplant.

Next came more intense testing than living patients could tolerate. Every week doctors biopsy the kidney, putting samples under the microscope to spot any hints of rejection. Blood is continually monitored, the spleen got a peek, and nurses keep close watch that the body is being properly maintained on the ventilator.The first few weeks, Griesemer checked lab test results and vital signs multiple times a day: “You’re like, OK, hopefully things are still good — but is this the day it starts to turn?”