The ‘worst version’ of COVID is spreading. Can we update our vaccines in time?

For the past 18 months, the original COVID-19 vaccines — first as a two-dose series, then as boosters — have done an extraordinary job protecting us from illness, hospitalization and death. In the world, 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 evolve, and vaccines should too.

That was the big picture from a pivotal meeting this week of the US Food and Drug Administration’s expert advisory panel. The question before them was simple: Faced with an expected winter surge, vaccine makers should adjust their next booster shots to target Omicron — the ultra-infectious variant that has spent the last seven months worldwide in a form or another – or they should. stick with the tried and true recipe 2020?

The panel voted 19-2 on Tuesday in favor of the Omicron boosters. The question now, though, is who version of Omicron the next round of shots should target.

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

A health worker administers a dose of a Moderna COVID-19 vaccine in Norristown, Pennsylvania, in 2021. (Matt Rourke/AP)

For those who haven’t been paying attention, the Omicron strain that triggered last winter’s massive wave of COVID (BA.1) is now extinct. In March, it was supplanted by the even more transmissible BA.2 … which was supplanted in May by the even more transmissible BA.2.12.1 … which is now replaced by the even more transmissible BA.4 ( you guessed it) BA.5.

Experts say that BA.5 is the one that worries: “The worst version of the virus that we have seen”, as Dr. Eric Topol, the founder of Scripps Research Translational Institute, he recently put it on. Together, the closely related BA.4 and BA.5 now account for the majority of new US COVID cases, according to the the latest data from the Centers for Disease Control and Prevention – but BA.5 (36.6%) spreads much faster than BA.4 (15.7%). In early July, it will be the dominant race in the United States

This is problematic for several reasons. To our immune system, the distance from BA.1 to BA.4 and BA.5 highly mutated is “much bigger“Topol writes, that the distance from the original BA.1 virus to previous blockbuster variants like Alpha and Delta – making them harder to recognize and respond to. According to the latest research, this could mean:

None of this will bring the United States back to square one. Despite high levels of cases, there are now fewer US COVID patients in intensive care units than there were during earlier stages of the pandemic, and the national death rate (about 300-400 per day) is close to all time low. Acquired immunity, multiple vaccinations and better treatment options help – a lot.

But combined with reduced vaccine protection and disappointing booster intake among seniorsthe accelerated evolution of the virus and a new aggressive trajectory – towards greater transmissibility, evasiveness and possibly pathogenicity – could cause reinfections and significant disturbances if not addressed.

It could also put vulnerable Americans at risk in the coming months.

A person wearing a mask walks past a sign in New York City that outlines the CDC's guidelines for controlling the spread of COVID.

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

At the end of April, BA.5 hits Portugal; from June, more Portuguese die from COVID every day than during the winter of the country Omicron peak. To be sure, Portugal has a larger elderly population (23%) than the United States (16%), but not by much. And the vaccination rate there is 87%, compared to only 67% in America. Meanwhile, Portugal’s booster rate is almost twice as high like ours. Infection and hospitalization rates are now on the rise in much of the rest of Europe as well.

At Tuesday’s FDA advisory meeting, Justin Lessler, an epidemiologist at the University of North Carolina at Chapel Hill, presented a series of projections on 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, again, is outcompeting its cousin BA.4 – will soon be everywhere, it seems logical that the next version of the vaccine should be adapted to fight.

Although that is not necessarily the plan. Both Pfizer and Moderna have already launched clinical trials for redesigned fall boosters… but those boosters are optimized to counter the now-defunct BA.1 rather than the soon-to-be BA.5. According to data presented on Tuesday by Pfizer, its existing BA.1 booster generated a significantly lower level of neutralizing antibodies against BA.4 and BA.5 than against BA.1.

Pfizer-BioNTech COVID-19 vaccine vials are being prepared for packaging.

Vials of the Pfizer-BioNTech COVID-19 vaccine are being prepared for packaging in 2021. (Pfizer via AP)

But in mice, at least, a booster containing BA.4 and BA.5 produces a higher neutralizing response to all variants of the Omicron (including BA.4 and BA.5) than the original vaccine.

Despite the concern about the “scarce” data on whether bivalent boosters (equal parts of original strain and Omicron) work better than monovalent boosters (100% Omicron), and on whether it is worth waiting for the promising non-mRNA vaccine of Novavax reaches the market, the panel. mostly agree that the BA.4/BA.5 boosters make sense. The FDA is leaning that way too. Pfizer said it was “prepared” to deliver the new boosters by the first week of October; Modern, from the last week of October or early November – “assuming no clinical data requirements”.

This means no human trials – only animal trials and laboratory tests. That may sound scary to some, but regulators already use the same expedited process to update the flu vaccine every year — and there’s no mechanism by which minor mRNA tweaks will make Pfizer and Moderna’s revised shots any less safe. the billion doses so administered. away in the world. Otherwise, the United States will miss its fall-winter deadline, and the rapidly evolving virus will continue to outpace vaccines.

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

A syringe is prepared with the Pfizer COVID-19 vaccine.

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

In the future, pursuing variants may not be the most effective or efficient approach to COVID vaccination. As Topol said, “by the time a BA.5 vaccine booster is potentially available, who knows what … the predominant strain” will be? That’s why it was welcome news on Wednesday when Pfizer and BioNTech announced that they plan to “start human trials of next-generation shots that protect against a wide variety of coronaviruses in the second half of the year “. according to a Reuters report.

These include “T-cell booster shots, designed to protect primarily against serious illness if the virus becomes more dangerous,” and “pan-coronavirus shots that protect against the broader family of viruses and their mutations.” Nasal vaccines are intended to stop the infection before it starts are promised too.

But these are all long-term propositions. This year, at least, a BA.5 booster is probably our best bet to minimize infection, disease and death during another likely winter surge.

“I fully expect more evolution in the coming months, but that evolution will most likely be above BA.4/BA.5 – and so [it] should not deter vaccine updates,” virologist Trevor Bedford of the Fred Hutchinson Cancer Research Center in Seattle. he wrote earlier this week. “I believe that the decision-making process can be reduced to: the composition of vaccines that can be manufactured in time for the fall distribution, which we expect to generate the highest. [protection] against BA.4/BA.5?

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