By Peter Loftus 

Moderna Inc. said its Covid-19 vaccine appeared to protect against emerging variants of the coronavirus in laboratory tests, but as a precaution it would test whether a booster shot improves immune responses and develop a new vaccine targeting the strain first identified in South Africa.

The company said Monday its vaccine produced immune-system agents known as neutralizing antibodies that worked against the emerging virus variants tested, including strains first evident in the U.K. and South Africa.

That means the Moderna vaccine likely still protects against the emerging strains, but a weaker response to the South Africa variant suggests the hazards of a virus that could mutate in significant ways while countries race to vaccinate against it.

The new strains appear to spread more easily from person to person, and there are signs that the U.K. variant is more deadly than earlier forms of the virus. The strains appear to be spreading around the world, prompting U.S. health authorities to warn the variant first detected in the U.K. could become dominant by March.

The variant first found in South Africa hasn't been detected in the U.S., Anthony Fauci, the nation's top-infectious disease expert, said Sunday. To curb the spread of new strains into the U.S., President Biden on Monday restricted travel from South Africa and re-established a ban on most travel into the U.S. from Europe, the U.K. and Brazil.

Since the new strains emerged, vaccine makers have been saying they think their vaccines will still provide protection. Moderna's announcement supports research by outside scientists indicating the protection against the strain identified in South Africa, in particular, may not be as strong though still effective.

Pfizer Inc. and BioNTech, which make the only other Covid-19 vaccine authorized for use in the U.S., are continuing to run lab studies of their vaccine against new variants, a Pfizer spokeswoman said.

Moderna said its vaccine induced production of neutralizing antibodies against the strain first identified in the U.K., known as B.1.1.7, at levels comparable to prior variants. Yet neutralization decreased sharply in the case of the strain in South Africa, known as B.1.351, according to a paper posted on the preprint server bioRxiv. Researchers from both Moderna and the National Institutes of Health's Vaccine Research Center conducted the analyses. The paper hasn't yet gone through the standard peer-review process.

Even with the decrease, Moderna said, the vaccine-induced antibody response to the B.1.351 variant remained above levels deemed protective. The company said it expects its standard two-dose vaccine to guard against the emerging viral strains to date.

It will test, however, whether adding a booster dose of its original vaccine can bolster antibody levels against emerging strains. The company is also developing a new version of the vaccine that targets more specifically the mutations in the South Africa variant and will test whether given as a booster shot it induces a better immune response.

The company plans to start within a couple of months a Phase 1 study of the booster shot aimed at the South African variant.

"In the event that this virus continues to mutate in this direction, and a year from now is still circulating in some way, we think it's prudent that we have tools like a booster vaccine to address that," Moderna President Stephen Hoge said in an interview.

Moderna said it expects that its booster shot -- whether for the original vaccine or one targeting the variant first identified in South Africa -- could be given in combination with vaccines from other companies.

The coronavirus variant in South Africa has several mutations in its so-called spike protein, which is found on the surface of the virus. Moderna's vaccine and most others are designed around the spike protein or its genetic code as a way to induce an immune response to the virus; and so, mutations in the protein have the potential to hurt the performance of a vaccine.

The modified vaccine Moderna is developing is designed to trigger the production of the spike protein specific to the South African variant, which in turn induces an immune response.

The company believes it can quickly design and manufacture the modified vaccine and have it ready for human testing over a shorter span than was the case with the original vaccine. Last year, it shipped the first batch for testing about six weeks after selecting the initial design, and the first human study started within two months.

"I believe we should be able to go even faster now," Chief Executive Stephane Bancel said last week during an interview for the WSJ Executive Membership Series. "If in the future we encounter a mutation that requires a new vaccine, we could very quickly, in a matter of a month or so, get a new vaccine out."

Mr. Bancel said he didn't think regulators would require such a vaccine to go through the full series of human studies since it would have the same underlying gene-based technology as the original vaccine.

Moderna's move points to the potential that Covid-19 vaccines will have to be modified -- and possibly given to people as repeat doses -- to address a changing virus.

"We may have to begin thinking about this like influenza vaccines and start rolling out regular annual vaccinations" with modified vaccines that target different strains, said Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Texas.

Last week, Pfizer and BioNTech said their vaccine -- which uses a gene-based technology like that of Moderna's shot -- appeared to be protective against the U.K. virus strain, based on lab studies.

"The virus is evolving and it's getting fitter and better at what it needs to do," said Dr. Hoge, Moderna's president. "And both the South African and the U.K. strains, we're seeing clearly increases in transmission, and the potential for infectivity."

Moderna shares were ahead 11% at $145.23 in afternoon trading Monday.

--Jared S. Hopkins contributed to this article.

Write to Peter Loftus at peter.loftus@wsj.com

 

(END) Dow Jones Newswires

January 25, 2021 15:40 ET (20:40 GMT)

Copyright (c) 2021 Dow Jones & Company, Inc.
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