The ‘worst model’ of COVID is spreading. Can we replace the vaccine in time?

Over the past 18 months, the original COVID-19 vaccine – first as a two-dose series, then a booster – has done an extraordinary job of protecting us from illness, hospitalization and death. death. Globally, they In 2021 alone, nearly 20 million lives have been saved. Even today, unvaccinated Americans are twice as likely to test positive for COVID than vaccinated Americans – and six times more likely to die from disease.

But viruses evolve, and so do vaccines.

That’s the big picture from this week’s important meeting of the U.S. Food and Drug Administration’s expert advisory panel. The question for them is simple: In the face of an expected winter spike, should vaccine manufacturers adapt their upcoming booster shots to target Omicron — the variable? The super-spreaders that have spent the past seven months spreading around the world in one form or another – or should they stick with the tried-and-true formula in 2020?

The council voted 19-2 on Tuesday in favor of the Omicron booster. However, the question now is version of Omicron, the next series of images will target.

A healthcare worker injects a dose of Moderna COVID-19 vaccine.

A healthcare worker injects a dose of the Moderna COVID-19 vaccine in Norristown, Pa., in 2021. (Matt Rourke/AP)

For anyone not paying attention, the Omicron strain that caused the massive COVID wave (BA.1) last winter is now extinct. In March it was superseded by the more transmittable BA.2… was replaced in May by the even more transmittable BA.2.12.1… now being replaced by (you guessed it) BA. 4 is even easier to transmit, and BA.5.

Experts say BA.5 is something to worry about: “The worst version of the virus we’ve ever seen,” as Dr. Eric Topol, founder of the Scripps Research Translational Institute, recently booked it. Together, the closely related BA.4 and BA.5 now account for the majority of new US COVID cases, according to Latest data from the Centers for Disease Control and Prevention – but BA.5 (36.6%) is spreading much faster than BA.4 (15.7%). At the beginning of July, it will be the dominant line in the US

It’s troublesome for a number of reasons. For our immune system, the distance from BA.1 to BA.4 and heavily mutated BA.5 is “much bigger“Topol writes, more than the distance from the original BA.1 virus to earlier blockbuster variants like Alpha and Delta – making them harder to recognize and react to. According to the latest research, that could mean:

None of this will put the United States back in square one. Despite the high level of cases, there are now fewer COVID-19 patients in the US in intensive care units than in previous phases of the pandemic, and the nationwide mortality rate (about 300-400 per year). days) near an all-time low. Acquired immunity, more vaccinations and improved treatment options are helping a lot.

But combined with waning vaccine protection and disappointingly enhanced uptake in the elderlythe virus’s accelerated evolution and aggressive new trajectories – towards greater transmissibility, evasion, and possibly pathogenicity – could cause substantial re-finishing and discontinuity if not resolved.

It could also endanger vulnerable Americans in the coming months.

A person wearing a face mask walks past a sign in New York City outlining CDC guidelines for controlling the spread of COVID.

A sign seen in March in New York City outlining CDC guidelines for controlling the spread of COVID. (John Minchillo / AP)

At the end of April, BA.5 attacked Portugal; to June, many Portuguese die from COVID every day than in the country’s winter Omicron peaks. Sure, Portugal has a larger elderly population (23%) than the US (16%), but not by much. And the vaccination rate there is 87%, compared with just 67% in the US. Portugal’s boost rate, meanwhile, is almost twice as tall like ours. Rates of infections and hospitalizations are now increasing over much of the rest of Europe.

At an FDA advisory meeting Tuesday, Justin Lessler, an epidemiologist at the University of North Carolina at Chapel Hill, presented a series of predictions about how the virus could affect the United States in the coming months. The most optimistic scenario? About 95,000 new deaths between March 2022 and March 2023. Most pessimistic? More than 200,000.

So given that BA.5 – again, outperforming its cousin BA.4 – will be everywhere soon, it seems logical that the next version of the vaccine should adjusted to counteract it.

However, that is not necessarily the plan. Both Pfizer and Moderna have conducted clinical trials for redesigned fall boosters… but those boosters are optimized to counter the now nonexistent BA.1 rather than BA.5 about to dominate. According to data presented by Pfizer on Tuesday, their existing BA.1 booster create a significantly lower level of neutralizing antibodies against BA.4 and BA.5 rather than against BA.1.

Pfizer-BioNTech COVID-19 vaccine vial is prepared and packaged.

The Pfizer-BioNTech COVID-19 vaccine vial is scheduled to be packaged in 2021. (Pfizer via AP)

However, in mice, at least, one enhancer contained BA.4 and BA.5 . produces a higher neutralizing reaction for all Omicron variants (including BA.4 and BA.5) compared to the parent vaccine.

Despite concerns about “poor” data on whether divalent boosters (original and Omicron equal parts) perform better than monovalent (100% Omicron) boosters and whether it is worth waiting for Novavax’s promising non-mRNA vaccine to hit the market. most agree that BA.4/BA.5 boosters make sense. The FDA is moving in that direction, too. Pfizer said it was “preparing” to deliver the new booster in the first week of October; Moderna, in the last week of October or early November – “assuming no clinical data is required.”

That means no human testing – just animal testing and lab testing. That may sound intimidating to some, but regulators already use the same accelerated process to update flu vaccines every year — and there’s no mechanism by which small mRNA edits would make the modified Pfizer and Moderna injections less safe than the billions of such injections worldwide. Otherwise, America will miss the fall-winter deadline, and the rapidly evolving virus will continue to outpace vaccines.

The FDA itself will decide “very quickly” what to recommend; Manufacturers will follow their lead.

A syringe prepared with the Pfizer COVID-19 vaccine.

A syringe prepared with the Pfizer COVID-19 vaccine in Chester, Pa., in 2021. (Matt Rourke/AP)

Going forward, chasing variants may not prove to be the most effective or efficient approach to COVID vaccination. As Topol said, “at a time when BA.5 vaccine boosters are likely, who knows… the dominant strain” will be? That’s why it was welcome on Wednesday when Pfizer and BioNTech announced that they plan to “start human trials of next-generation shots that protect against multiple coronaviruses in the second half of the year.” now”. according to a Reuters report.

These include “T-cell booster shots, designed to primarily fight severe illness if the virus becomes more deadly” and “pan-coronavirus shots that protect against a broader group of viruses and its mutations.” The nasal vaccine is meant to stop the infection before it starts also full of promise.

But those are all longer-term proposals. This year, at least, a BA.5 booster is probably our best bet for minimizing infections, illness, and deaths during a possible winter spike.

“I fully expect the next evolution to happen in the coming months, but this evolution will most likely be on BA.4 / BA.5 – and so on. [it] should not get in the way of vaccine updates,” said virologist Trevor Bedford of the Fred Hutchinson Cancer Research Center in Seattle. wrote earlier this week. “I believe the decision-making process can be shortened to: vaccine preparations can be produced in time for distribution in the fall, we expect to produce peak production. [protection] against BA.4 / BA.5? “

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