Health

Moderna says its modified Covid vaccine works better against Omicron


Moderna to announce preliminary results on Wednesday on an updated coronavirus vaccine aimed at the Omicron variant, calling it “our top candidate” to serve as a US booster in the fall.

The company’s researchers tested a booster dose that combines the original vaccine with a vaccine that specifically targets Omicron, the variant that became dominant last winter. They found that among people with no evidence of prior coronavirus infection, the combination produced levels of neutralizing antibodies against Omicron that were 1.75 times higher than the currently available Moderna vaccine.

While those results may seem encouraging on their faces, many experts worry that the virus is evolving so quickly that it outstrips the ability to modify a vaccine, at least as long as the United States relies on it. human clinical trials for results.

Moderna’s new findings, from a clinical trial with 814 volunteers, show that the updated vaccine produces a significantly stronger immune response against Omicron than the existing vaccine a month after it was released. booster injection. The booster shots follow the previous three doses of Moderna vaccine.

But Omicron has been generating extra variables for months, and some vaccine experts say what matters now is how well the new enhanced formula will protect against the latest extra variable, BA.4 and BA.5, not Omicron itself. First discovered in South Africa earlier this year, these two subspecies now accounts for 13 percent of new cases in the USand is spreading rapidly. By some estimates, within a month, they could compete the other two Omicron sub-variables, BA.2 and BA.2.12.1dominant at the moment.

Moderna has not released any data on how the updated vaccine works against BA.4 or BA.5. In a presentation Wednesday morning, Dr. Stephen Hoge, the company’s president, said that researchers are still gathering data on them and other subvariables.

But he says that a very small sample, along with other studies isolated, suggests that the level of neutralizing antibodies triggered by the updated vaccine is two to three times lower than the BA subvariables. .4 and BA.5, compared to the activation level against Omicron. But he said those levels “remain a very comfortable place,” a view echoed by at least one federal health official who reviewed the data.

Moderna officials said they could not yet say whether the reconfigured vaccine would provide more lasting protection than the existing one, but they expect it to work, based on the findings. earlier from a study of a vaccine reconfigured based on another variant, released in April.

The latest subtypes seem to spread faster than earlier versions of Omicron and may be better at dodging the immune system’s defenses. It is not clear whether they cause more severe disease. Dr. Anthony S. Fauci, chief medical adviser to the White House, said in an interview on Tuesday that South Africa, where BA.4 and BA.5 were popularhas “seen a slight increase in hospitalizations, but ICU utilization and mortality are actually at a steady low.”

In any case, given the rate at which the virus mutates, some vaccine experts say it makes more sense to target the most recent versions of it rather than viruses that have already been or will soon be eliminated. overcome.

The problem is that Moderna and Pfizer – the other main US coronavirus vaccine makers – don’t currently have enough time to run more human clinical trials and still produce the shots before the fall, when the administration Biden is hoping to be able to deliver an updated vaccine to combat what public health experts predict will be a winter spike.

That could force regulators to choose up-to-date vaccines based on data from laboratory trials and trials involving mice or other animals, rather than robust trials. on body. It is also possible that a new variant or other interesting sub-variant will appear in the fall, further complicating the picture.

The outside advisor to the Food and Drug Administration is See you on June 28 discuss which vaccine formulation will work best as a fall booster; vaccine manufacturers have said they will start production soon.

“Of course, the final decision is always with the FDA,” Dr. Fauci said. “But what the FDA is probably going to do is keep as many irons on fire as possible. And they may need to go back to alternative decision pathways, which are possible laboratory data and animal data. “

When asked if Americans would accept a fortified formulation without lengthy human trials, he said, “People who really care about protecting themselves will be.”

John Moore, a virologist at Weill Cornell Medicine in New York, said at this point, many healthcare professionals will feel comfortable as the pandemic shifts to a different paradigm for coronavirus vaccine development, like model used for annual flu vaccine revision. The composition of the flu vaccine is changed every year to accommodate new variations with minimal new human trials, federal health officials said.

Moderna’s trial of a vaccine targeting Omicron began in late February. The average age of the participants was 57. All volunteers received three doses of Moderna’s currently available vaccine – two, followed by a booster dose given an average of eight months after the second dose. .

About four and a half months after that first booster, 377 volunteers received a second booster with an existing vaccine, while 437 received a booster designed to fight Omicron. The updated booster produced a stronger immune response in both people who were previously infected with the virus and those who were not.

Overall, people who received the updated booster had 59 percent higher levels of neutralizing antibodies than those who received the existing booster, according to data published by Moderna.

Antibodies are the body’s first line of defense against infection from the coronavirus. Other immune responses also against Covid-19 were not measured; those tests are much more complicated and time consuming to conduct.

Dr Paul Burton, Moderna’s medical director, described the results as very encouraging. “We really feel this is a fundamental turning point in the fight against this virus – that we can adapt to a variant,” he said.

But Dr Moore said the less than two-fold increase in neutralizing antibodies compared with an existing vaccine was only “a modest benefit”.

“Does that justify switching vaccine ingredients, with the costs and logistics and everything else involved?” he asks. “That’s what the argument will be about.”

Pfizer and BioNTech, the German partner, are also testing the Omicron-specific vaccine and expect to publish the results soon.

In April, Moderna Preliminary results announced on a vaccine retooled to attack the Beta variant, first discovered in late 2020. The company says that version of the vaccine triggered a stronger immune response than the original formulation. head, not only against Beta but also against the Delta and Omicron variants. Although Moderna officials say the added protection against Omicron persists for six months, they say they expect an Omicron-specific vaccine to be a better candidate.



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