Will Americans have the right COVID-19 vaccine this fall? Maybe

In a few months, the weather will be fresh, the holiday season is fast approaching, and the coronavirus could enter its third straight winter of death and devastation.

That prospect has drawn federal agencies and their scientific advisors into a high-stakes guessing game.

The question: How should the COVID-19 vaccine change?

Of course, circumstances have changed. The strains of coronavirus responsible for 97% of infections today — BA.4, BA.5, and BA.2.12.1 — didn’t exist in 2021, let alone 2020. Yet all vaccines currently available in the US are designed to detect them the version that left China in January 2020.

The recordings did an admirable job. Researchers credit them with saving 1.9 million lives in the US in their first year of availability, and they continue to provide robust protection against serious illness and death from COVID-19. However, the ubiquitous omicron subvariants have several mutations in their crucial spike proteins that make them less detectable to an immune system primed to fight the 2½-year-old virus.

The result: A real study found that protection from three doses of the mRNA vaccine against Omicron was half that of the previous Delta variant. Laboratory studies have also shown that exposure to Omicron causes the vaccinated immune system to secrete far fewer antibodies.

In addition, the immunity induced by vaccines and first rounds of boosters has waned. The Biden administration has placed an order for 105 million doses for a fall refresher campaign, with an option to buy millions more.

Determining what prescription should be included in those doses to provide optimal protection – the “composition” of the vaccine – is an exercise in educated guesswork.

Your challenge consists of several parts. First, experts need to predict which coronavirus variant – or which variants – will dominate the US landscape in late 2022 and into 2023.

They then need to predict whether modified versions of key vaccines will be effective and whether they pose new challenges in terms of safety, cost, or timely distribution.

Finding a timely and accurate solution to all of this “is really challenging, and it’s the hardest science,” said Dr. Peter Marks, the US Food and Drug Administration’s vaccine chief, told the agency’s independent advisers last month.

If the FDA waits too long to act on the sparse data available, Americans could have subpar protection when the coronavirus rises again, Marks warned. But speed comes with risks. When manufacturers introduce newly formulated vaccines without first testing them in full clinical trials, the FDA must have confidence that existing surveillance systems can quickly detect new safety issues, he said.

“We’re essentially being asked to have a crystal ball,” said Dr. Arnold Monto, who chairs the FDA’s Vaccine Advisory Committee.

And if public health officials make the wrong choices, a pandemic-weary nation could lose faith in a vaccine we’re likely to need for years to come.

In many ways, the task of updating COVID vaccines is a turbocharged version of a dilemma that vaccine experts have faced with the flu vaccine for decades.

Each year, multiple strains of the insidious influenza virus circle the globe, infecting new populations. The mixture of the circulating strains changes as does their genetic make-up.

Therefore, in early autumn and early spring, the World Health Organization is gathering an international panel of vaccine experts to assess which mix of viruses is most likely to circulate over the next six months. Their results dictate the composition of vaccines offered for the upcoming flu season.

Sometimes their predictions are accurate, but not always. Between 2001 and 2010, annual influenza vaccines protected against circulating influenza B strains only 50% of the time. During the 2014-15 flu season, an incorrect guess about influenza A virus led to 758,000 flu hospitalizations among older Americans and 148 childhood flu deaths.

The COVID-19 vaccines of choice in the US — BioNTech’s Pfizer and Comirnaty and Moderna’s Spikevax — have a key advantage over traditional flu vaccines: Their mRNA technology makes it possible to change composition at comparatively startling speeds. Millions of targeted doses of both vaccines will be available by September or October.

In order to extend the protection of a booster shot across the widest possible variety of variants, it would be ideal to know which of the Omicron subvariants is most genetically different from the original coronavirus strain. Mating the two in a single shot would give the vaccine “breadth” and make it more likely to offer protection against a wide variety of strains that continue to circulate.

It is easy to assume that BA.4 and BA.5 (which share the same spike protein) have the least in common with the ancestral tribe because they appeared only recently.

But the fledgling field of genetic epidemiology is not so sure. dr University of Melbourne’s Kanta Subarrao, who studies the immune system’s response to emerging viral diseases, said Omicron’s BA.1 subvariant is actually the bigger outlier.

If it were up to her to decide which version of the coronavirus to target with a fall booster, “I would choose BA.1,” Subarrao said at the recent FDA advisors meeting.

The agency did not agree. In late June, the FDA asked vaccine manufacturers to produce “bivalent” doses that combine the original vaccine with one that recognizes BA.4 and BA.5. Who is recommended to get it has yet to be determined.

dr Paul Offit, a virologist and immunologist at the University of Pennsylvania, thinks both approaches are wrong. In his view, the original vaccine and boosters are doing a good job of preventing serious illness and death, and the potential benefits of targeted treatment with Omicron are too uncertain to justify the risks of delivering a vaccine that has not undergone a full clinical study .

Sure, a bivalent vaccine booster might stimulate the immune system to make more antibodies than a regular booster, but that doesn’t necessarily mean recipients would be better off, Offit said in an interview.

“If they had given me the choice of voting ‘no’ or ‘damn no’, I would have voted ‘damn no,'” he said.

For Offit and most other vaccine experts, the ideal response to a changing virus would be to develop a universal vaccine capable of neutralizing any variants that might arise.

It’s an approach that has been the holy grail of influenza research, and despite years of work, it remains incredibly elusive.

To withstand the evolution of a virus, some scientists have attempted to design vaccines that target a component that doesn’t change — say, a protein that performs a household task crucial to its survival. Others have looked at animals like llamas and alpacas, which produce very small antibodies that can adapt to viruses as they change.

Recently, a team led by scientists at Caltech developed a multi-pronged vaccine containing pieces from eight betacoronaviruses, including the one that causes COVID-19. When given to mice and monkeys, it trained their immune systems to recognize a variety of viruses, effectively showing them a miniature family portrait.

The next step is a phase 1 human clinical trial, in which many promising universal vaccine candidates have failed.

“It’s not for lack of money. It’s not for lack of desire or effort,” Offit said. “It’s just difficult to make universal vaccines work.”

https://www.latimes.com/science/story/2022-07-12/will-americans-have-the-right-covid-19-vaccine-this-fall-omicron Will Americans have the right COVID-19 vaccine this fall? Maybe

Russell Falcon

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