US experts are struggling with how to upgrade COVID-19 vaccines

WASHINGTON (AP) – More than two years after the COVID-19 pandemic, US health officials have been grappling with how to keep the vaccine updated to best protect Americans against the ever-changing coronary heart disease virus.

On Wednesday, a group of vaccine advisers from the Food and Drug Administration spent hours debating key questions to improve the shots and carry out future campaigns. They did not come to any definite conclusion.

The questions faced by the experts included: How often should vaccines be updated against new strains, how effective should they be in justifying approval and whether updates should be coordinated with international health authorities.

Last week, the FDA approved the fourth dose of the Pfizer or Moderna vaccine for anyone 50 years of age or older and for some younger people with severely weakened immune systems. It is an effort to get ahead of another possible wave.

But the head of the FDA vaccine, Dr. Peter Marks, admitted at the meeting, “we simply can not be empowering people as often as we are. He called the latest stimulus update a “stop” measure to protect vulnerable Americans while regulators decide whether and how to optimize existing vaccines.

Marks warned that declining vaccine protection, new varieties and colder autumn weather could increase the risk of more waves.

“Our goal here is to stay ahead of future variants and epidemics and ensure that we do our best to reduce the incidence of COVID-19 diseases and deaths,” Marks said, adding that he expects more vaccine committee meetings in the coming months.

Some of the key questions that the panel discussed:


One area where experts seemed to agree is that vaccines should be judged on their ability to prevent serious illness leading to hospitalization and death.

“We need to focus on the worst case scenario, which is a serious disease, and we need to change our stock when we are losing that battle,” he said. Mark Sawyer of the University of California, San Diego.

By that measure, current vaccines have performed remarkably well.

In the latest omicron-driven increase, two doses of vaccine were nearly 80% effective against the need for a respirator or death – and stimulation pushed that protection up to 94%, federal researchers recently said.

But only about half of Americans eligible for the third shot have received one shot. And many experts said it was unsustainable to keep asking the United States for a boost every few months.

A jury from the Centers for Disease Control and Prevention suggested that 80% protection against serious diseases could become the standard for evaluating vaccines.

“I think we may have to come to terms with that level of protection and then use other means to protect individuals through treatment and other measures,” he said. Amanda Cohn, Chief Physician of the CDC.

Presentations at the meeting by government health professionals and independent scientists highlighted the challenges of predicting when the next major COVID-19 variant could appear.

Trevor Bedford, a pathologist at the Fred Hutchinson Cancer Research Center, said a large new strain like omicron could appear anywhere from 1.5 years to once a decade, based on current data. In view of this unpredictability, researchers will need methods to quickly determine whether the current vaccine works against new variants.


All three COVID-19 vaccines currently in use in the United States are based on the original version of the coronary artery virus that was introduced in late 2019. Updating the vaccines will be a complex task that will likely require coordination between the FDA, manufacturers and international health authorities.

To speed up market vaccinations, the FDA relied on research shortcuts to assess efficacy, primarily examining their early effects on the immune system’s antibody levels. A number of committee members said on Wednesday that they wanted stricter data from studies that monitor patients over time to see who gets sick or dies.

But that method would probably be too time consuming.

“We are looking at a riddle here in that it will be difficult to create all the data we want in a short time when a new variant emerges,” said Dr. Ofer Levy of Harvard Medical School.

A representative of the US Biomedical Advanced Research and Development Authority outlined the narrow window that manufacturers could face to restructure, research and mass-produce updated vaccines by September.

“If you’re not on your way to a clinical trial in early May, I think it’s going to be very difficult to have enough products between manufacturers to meet demand,” said Robert Johnson, BARDA’s Deputy CEO.

The process of updating the annual flu vaccine offers one possible model, as stated by a representative of the World Health Organization.

Twice a year, WHO experts recommend updates on influenza vaccines to target new strains. The FDA then submits these recommendations to its own Vaccine Committee, which votes on whether they make sense for the United States, and lays the groundwork for manufacturers to fine-tune their shots and start mass production.

But COVID-19 has not yet fallen into a predictable pattern like the flu. And as the coronavirus develops, different strains can become prevalent in different parts of the world.

Several experts said they needed more meetings with more FDA data and recommendations to determine policy.

“We have never been here before. We are all working together to do the best we can and it is very complicated, “said Oveta Fuller at the University of Michigan School of Medicine.


The Associated Press’s Department of Health and Science receives support from the Howard Hughes Medical Institute’s Department of Science. AP is solely responsible for all content.

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