CAMBRIDGE, Mass. – Moderna, which makes one of the two authorized COVID-19 vaccines, is set to launch a clinical trial of a new vaccine designed to combat a variant of the virus, the company announced Wednesday.
The company says it has produced enough of its variant-specific candidate vaccine, called mRNA-1273.351 to begin testing it in people.
Any change to address variants, which other vaccine makers also are working on, would need to be approved by the U.S. Food and Drug Administration.
In a study published last week, Moderna showed that blood from people who received the current vaccine includes neutralizing antibodies against the major known variants. But only one-sixth of their antibodies were protective against the B.1.351 variant of the virus, which originated in South Africa, and which is the target of its new vaccine.
It is not clear whether this reduced antibody level is sufficient to protect people against symptomatic or serious cases of COVID-19 from this new variant.
That's why "out of an abundance of caution," the company said in a news release it has begun pursuing two possible strategies against the variant: giving people a booster dose of the original vaccine to increase antibody levels, and developing two variant-specific vaccines, which could be given instead of the original one.
It will test several variations of a booster, the company said, including a single, low-dose shot of the variant-specific vaccine; a shot that includes both the original vaccine and the variant-specific one; and a third low-dose version of the original vaccine.
According to FDA guidance, the company plans to evaluate the safety and immune effects of these approaches in people who have not been vaccinated against COVID-19, and in those who received the original vaccine, mRNA-1273.
The National Institute of Allergy and Infectious Disease will help lead the clinical studies to see whether mRNA-1273.351 can boost immunity against the variant. In its announcement Wednesday, the company said it already has shipped sufficient doses of this variant-specific vaccine needed for testing.
“As we seek to defeat COVID-19, we must be vigilant and proactive as new variants of SARS-CoV-2 emerge," Stéphane Bancel, Moderna's CEO, said in a prepared statement, referring to the virus that causes COVID-19. "We are moving quickly to test updates to the vaccines that address emerging variants of the virus in the clinic."
The lower doses hopefully will work for the booster, Bancel said, allowing the company to stretch its limited vaccine supply.
Other leaders in the COVID-19 vaccine effort – Pfizer-BioNTech, Novavax, Johnson & Johnson and AstraZeneca-Oxford University – also have said they are working on new versions of their vaccines or boosters to increase their protection.
A third vaccine on the way: One-dose J&J COVID-19 vaccine meets criteria as safe and effective, FDA report finds
It's not yet clear whether a booster shot, which amps up the immune system, will be enough to protect against a new variant, or if an entirely new vaccine is needed.
Moderna is the first to release details about its effort.
In a congressional subcommittee meeting Tuesday, Pfizer's chief business officer, John Young, said his company is "preparing to respond quickly to initiate a study to investigate the effectiveness of a third booster of our vaccine in trial participants who have already received two doses."
He said Pfizer is discussing trial designs with the FDA.
"We will fight every step of the way until a devastating pandemic is under control," he said.
The Moderna vaccine, like the Pfizer-BioNTech one, is based on mRNA technology in which a simple change to the code will enable the recipient to make a slightly different protein. That's why they were both made so quickly last year, once it became clear which protein on the SARS-CoV-2 virus they should target. By getting the body to produce a protein from the virus, the vaccine trains the immune system to recognize that protein and immediately attack if the recipient is exposed to the virus.
On Monday, the FDA laid out guidelines for companies that want to change their vaccines to adapt to new variants. They will not be required to start from scratch, running gigantic clinical trials over many months as they have to win FDA authorization.
Instead, as with the flu vaccine, which is altered every year to cope with changing strains, COVID-19 vaccine versions will be tested in smaller groups to confirm safety and to examine immune responses for effectiveness.
Lab studies and some real-world evidence suggests that current vaccines will remain effective against a variant called B.1.1.7, which originated in the United Kingdom.
But they may not all work against B.1.351. Studies of AstraZeneca-Oxford University's collaborative vaccine showed it was barely protective at all against B.1.351 in South Africa, and that country has passed on using doses of the vaccine.
Johnson & Johnson's vaccine does seem to provide some protection there, and lab studies suggest that Pfizer-BioNTech's vaccine, like Moderna's, would continue to provide some protection against that variant, though it's not clear how much.
Even if it proves unnecessary to reconfigure vaccines to fight the B.1.351 variant, there may be another that comes along that will require a new vaccine, public health officials have said.
New variants of the virus will continue to emerge as COVID-19 continues to infect people across the globe. The only way to stop these variants is to reduce the spread of the virus, public health officials, including Dr. Anthony Fauci, America's top infectious disease doctor, have said.
"It really is the time to study effects of booster doses to new, emerging viral variants," Dr. Jesse Goodman, a professor of Medicine at Georgetown University and former chief scientist with the FDA, said in a Wednesday call with media.
Studies are needed to show whether people respond as expected to booster doses, and whether they cause any concerning safety problems.
And even if the virus doesn't escape protection from current vaccines, people might need boosters eventually, Goodman said.
"We don't know," he said, "how long immunity will last from these vaccines."
Contact Karen Weintraub at kweintraub@usatoday.
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This article originally appeared on USA TODAY: Moderna to begin trial of new COVID vaccine to address virus variant