For the past 18 months, the original COVID-19 vaccines – first as a two-dose series, then as boosters – have done an outstanding job of protecting us from disease, hospitalization and death. Worldwide, they saved nearly 20 million lives in 2021 alone. Even today, unvaccinated Americans are twice as likely as vaccinated Americans to test positive for COVID – and six times more likely to die from the disease.
But viruses are evolving and vaccines are needed.
This was the big picture of a key meeting this week of the US Food and Drug Administration’s expert advisory group. The question before them was simple: before the expected winter jump, should vaccine manufacturers set up their upcoming booster vaccines to target Omicron, the ultra-infectious variant that has spent the past seven months growing worldwide in one form or another? – or should they stick to the tried and tested recipe for 2020?
The panel voted 19-2 on Tuesday in favor of Omicron boosters. The question now, however, is which version of Omicron should be targeted in the next round of strikes.
Healthcare worker administers a dose of Moderna COVID-19 vaccine in Norwistown, Pennsylvania, in 2021 (Matt Rourke / AP)
For anyone who didn’t pay attention, the Omicron strain that caused the huge COVID wave (BA.1) last winter is now gone. In March it was replaced by the even more portable BA.2 … which was replaced in May by the even more portable BA.2.12.1 … which is now being replaced by (remember) an even more portable BA.4 and BA.5.
Experts say BA.5 is something to worry about: “The worst version of the virus we’ve seen,” as Dr. Eric Topol, founder of the Scripps Research Translational Institute, recently said. Together, the closely related BA.4 and BA.5 now account for the majority of new COVID cases in the United States, according to the latest data from the Centers for Disease Control and Prevention – but BA.5 (36.6%) is widespread. faster than BA.4 (15.7%). Until the beginning of July, this will be the dominant strain in the United States
This is worrying for several reasons. For our immune system, the distance from BA.1 to highly mutated BA.4 and BA.5 is “much greater,” Topol writes, than the distance from the original BA.1 virus to previous blockbuster variants such as Alpha and Delta – which makes it more difficult to recognize and respond to. According to the latest study, this could mean:
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None of this will bring the United States back to square one. Despite the increased incidence rates, there are now fewer COVID patients in the US intensive care unit than in previous phases of the pandemic, and national mortality (around 300-400 per day) is close to the lowest ever. Acquired immunity, many vaccinations and improved treatment options help a lot.
But combined with declining vaccine protection and frustrating booster use in the elderly, accelerating virus evolution and an aggressive new trajectory – towards greater portability, evasion and possible pathogenicity – can cause significant re-infections and disruption if not considered.
It could also threaten vulnerable Americans in the coming months.
A sign seen in March in New York outlining the CDC’s guidelines for controlling the spread of COVID. (John Minchilo / AP)
At the end of April BA.5 hit Portugal; until June, more Portuguese died of COVID each day than during Omicron’s winter peak in the country. Of course, Portugal has a larger adult population (23%) than the United States (16%), but not much. And the vaccination rate there is 87%, compared to only 67% in America. Meanwhile, the percentage of boosters in Portugal is almost twice as high as ours. The level of infection and hospitalization is now rising in much of the rest of Europe.
At Tuesday’s FDA consultative meeting, Justin Lesler, 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. The most pessimistic? More than 200,000.
So given that BA.5 – which is once again ahead of its cousin BA.4 – will soon be everywhere, it seems logical that the next version of the vaccine will be adapted to combat it.
Yet this is not necessarily the plan. Both Pfizer and Moderna have already launched clinical trials for redesigned fall amplifiers… but these amplifiers are optimized to counter the now-defunct BA.1, not the BA.5 that will soon be dominant. According to data presented Tuesday by Pfizer, their existing BA.1 booster generates significantly lower levels of neutralizing antibodies against BA.4 and BA.5 than against BA.1.
Pfizer-BioNTech COVID-19 vaccine vials ready for packaging in 2021 (Pfizer via AP)
However, in mice, at least a booster containing BA.4 and BA.5 elicited a higher neutralizing response to all Omicron variants (including BA.4 and BA.5) than the original vaccine.
Despite concerns about the “scarce” data on whether bivalent boosters (equal parts original strain and Omicron) work better than monovalent boosters (100% Omicron) and whether it is worth waiting for Novavax’s promising non-mRNA vaccine to hit the market. , the panel most agree that amplifiers BA.4 / BA.5 make sense. The FDA is also leaning towards this. Pfizer said it was “prepared” to deliver the new boosters by the first week of October; Moderna, until the last week of October or early November – “provided that there are no requirements for clinical data”.
This means that there are no human experiments – only animal experiments and laboratory tests. This may sound scary to some, but regulators are already using the same accelerated process to update the flu vaccine each year – and there is no mechanism by which minor changes in mRNAs make revised Pfizer and Moderna vaccines less safe than billions of doses. applied so far around the world. Otherwise, the United States will miss its fall-winter deadline and the fast-growing virus will continue to outpace vaccines.
The FDA itself will decide “very quickly” what to recommend; manufacturers will follow suit.
The syringe was prepared with the Pfizer COVID-19 vaccine in Chester, Pennsylvania, in 2021 (Matt Rourke / AP)
In the future, the pursuit of options may not be the most effective or efficient approach to COVID vaccination. As Topol said, “while a BA.5 vaccine booster is potentially available, who knows what … will be the predominant strain”? That’s why news was welcome on Wednesday, when Pfizer and BioNTech announced plans to “start testing humans on next-generation photos that protect against a wide variety of coronaviruses in the second half of the year,” according to a Reuters report.
These include “T-cell enhancement vaccines designed primarily to prevent severe disease if the virus becomes more dangerous” and “pancoronavirus vaccines that protect against the wider family of viruses and their mutations”. Nasal vaccines designed to stop the infection before it starts are also promising.
But these are all long-term proposals. This year, at least the BA.5 booster is probably our best bet to minimize infection, illness and death during another possible winter jump.
“I fully expect further evolution to take place in the coming months, but this evolution is likely to be above BA.4 / BA.5 – and so [it] it shouldn’t discourage vaccine updates, “said virologist Trevor Bedford of the Fred Hutchinson Cancer Research Center in Seattle earlier this week. “I believe that the decision-making process can be reduced to: formulations of vaccines that can be produced in time for the autumn spread, which we expect to generate the highest [protection] against BA.4 / BA.5? “
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