Covid-19 omicron images can be taken, but their effect is unclear

The United States authorized the first major change to the Covid-19 vaccine this week in an effort to stem the wave of infections and hospitalizations expected this fall.

But it’s not yet clear how much protection the new booster shots will provide. The Food and Drug Administration and the Centers for Disease Control and Prevention deleted the shots without any data from clinical trials examining the adjusted dose in humans.

The new boosters, authorized for those 12 years and older, target the highly contagious and immune-evasive sub-omicron BA.5 bacteria, which have triggered a breakthrough wave of infections in the summer. The footage also targets the original strain of the virus that first appeared in Wuhan, China, in 2019.

The nation’s top health officials acted urgently this summer to ensure the new boosters would launch in time by the fall. They worry that the declining effectiveness of older vaccines is opening a hole for omicrons causing another wave of hospitalizations this winter as people spend more time indoors where the virus is airborne. more contagious.

According to Heather Scobie, CDC epidemiologist, the number of deaths and hospitalizations has increased since April among the elderly, the most vaccinated age group in the US, as omicrons continue to mutate into more and more. subvariant can be contagious.

Dr. Peter Marks, the head of the FDA office that reviews the vaccine, said the new booster is intended to restore the high level of protection the vaccine demonstrated as early as 2021. But Marks acknowledged that its experts The federal government simply doesn’t know yet whether boosters will meet the high bar set by these dosages.

Marks told reporters in a news release: “We don’t know yet for a fact whether we’ll reach that same level, but that’s the goal. The conference follows FDA authorization on Wednesday.

The FDA will conduct monitoring to see if the booster meets that goal, Marks said. When the photos by Pfizer and Moderna were authorized in December 2020, they provided more than 90% protection against Covid.

Marks told reporters it will likely be at least a few more months before human data on the BA.5 boosters are made publicly available. But he said the FDA has essentially used the same process to enable the new boosters it has relied on for years to switch strains of the virus in flu shots.

“We’re pretty confident that what we’re experiencing is very similar to what we’ve done in the past with flu changes that we didn’t do clinical studies for in the United States,” says Marks. Ky. “We know from how the vaccine works and from the data that we have, we can predict how well the vaccine will work.”

The new booster could avert 2.4 million infections, 137,000 hospitalizations and 9,700 deaths if a new variant does not emerge, according to a forecast by a group of scientists forecasting the trajectory of the oceans. translate, called Covid-19 scenario modeling center.

But that forecast is based on optimistic assumptions about booster coverage and effectiveness, the scientists say. The model assumes that the injections will prove 80 percent effective in preventing disease, and that the public will embrace the new enhancers widely. There is no data on the effectiveness of the new injections and it is unclear how strong public demand will be for them.

The CDC estimates that an early fall vaccination campaign with boosters could save the United States between $63 billion and $109 billion in medical costs by preventing hospitalizations and ICU admissions.

Pfizer and Moderna was initially developing a new booster to target the first version of omicron, BA.1, which caused a massive wave of infections and hospitalizations last winter. But keeping up with the rapid evolution of the virus has proven to be a challenge.

At a time when the nation’s top health leaders were seriously moving in April to get new boosters ready, many subtypes of potentially infectious bacteria had rendered omicron BA.1 no longer available. popular. In June, the FDA asked vaccine manufacturers to shift gears and target omicron BA.5 after it rose to dominance.

The decision does not allow enough time for Pfizer and Moderna to complete human clinical trials on the new rocket before deploying the vaccine in the fall.

As a result, the FDA and CDC are relying on human data from clinical trials of BA.1 shots to understand how BA.5 boosters might work. They also relied on data from studies in which BA.5 boosters were tested on mice.

The CDC’s independent advisory committee backed Thursday’s statements in an overwhelming vote.

But some members of the panel also expressed concern about the lack of data on people.

“I really struggled with a vaccine with no reported clinical data for humans,” said Dr. Oliver Brooks, committee member and medical director of Watts HealthCare Corp in Los Angeles. who are actually going to get the vaccine.” Angeles.

Dr Pablo Sanchez, the only CDC committee member to have voted against the shots, called the decision to recommend a new booster without human data as premature.

“There’s a lot of hesitancy about vaccines – we need data on people,” said Sanchez, a professor of pediatrics at Ohio State University.

Doran Fink, deputy director of the FDA’s vaccine review division, told hesitant committee members that the new boosters use the same manufacturing process as the older vaccines and contain the same ingredients. amount of mRNA, the code that instructs human cells to produce. proteins that stimulate an immune response to fight Covid.

Fink says the BA.1 and BA.5 images are similar enough to use data from human BA.1 trials to get a good idea of ​​how the new BA.5 boosters will perform.

Pfizer and Moderna presented data at the CDC meeting showing that BA.1 shots trigger a stronger immune response in humans than older vaccines. Studies in mice from both companies of BA.5 scans also showed a stronger immune response.

CDC Director Dr. Rochelle Walensky said last week that a longer wait for human data from the BA.5 scans could mean the booster becomes obsolete if a new variant emerges.

“There is always a question here of being too slow versus too fast,” Walensky told “Conversations on Health Care” in a radio interview. “One of the challenges is that if we wait for those data to appear in the human data … we’re going to use what I think is a potentially obsolete vaccine.”

Moderna completed its clinical trial registration last week and is expected to have results by the end of the year. Pfizer’s clinical trials are ongoing, though the company has not provided a timeframe for when the data will be available.

Brooks questioned why the FDA decided to use the BA.5 vaccine when clinical data were available for the BA.1 shots that the vaccine manufacturers were initially developing. Canada and the UK have authorized new enhanced firing targeting omicron BA.1

Fink said the US chose BA.5 based on the advice of an independent FDA committee, with data from South Africa showing that natural infection from the secondary variable provides broader protection than infection from BA.1 and the fact that BA.5 is dominating.

Although the committee members were somewhat hesitant about proceeding without human data, they agreed that the new boosters should have the same safety record as the older vaccines because they use same platform. The Covid vaccine has been given to millions of people in the United States with mostly mild side effects.

According to the FDA.

Dr. Sara Oliver, a CDC official, told the committee that the risk of myocarditis, an inflammation of the heart muscle, after BA.5 enhancement is unknown. But health officials predict it will be similar to the risk observed with older vaccines.

The Pfizer and Moderna vaccines are associated with an increased risk of myocarditis in young men and adolescent males mostly after the second dose. But the risk of myocarditis from a Covid infection is higher than with vaccination, according to the CDC.

Dr Grace Lee, chair of the CDC committee, sought to reassure the public that there was a robust surveillance system in place to monitor safety and that the panel would reconvene if any new concerns emerged. .

“I just want to make sure that members of the public are aware that we’re continuing to watch closely,” Lee said. “We have systems and teams that are continuing to monitor and meet.”

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