Moderna: Vaccine protects against British, S. African variants

The coronavirus vaccine developed by Moderna triggers an immune response that protected in laboratory tests against two variants of the virus first detected in Britain and South Africa, the company said Monday.

The finding was largely encouraging but contained a clear warning sign: Even though the vaccine generated disease-fighting antibodies that worked against the South African variant, that efficacy was diminished. Moderna said there was a reduction in response, prompting the company to design a new potential vaccine that could be added to the current twodose regimen.

As a precaution, Moderna announced that it will begin two new studies. The company will test adding a third shot of its current vaccine to boost its two-dose regimen. The biotechnology company also plans early human tests of the all-new vaccine specific to the South African variant, using it as a booster to prime the immune system to the new strain.

“The virus is changing its stripes, and we will change to make sure we can beat the virus where it’s going,” Moderna President Stephen Hoge said in an interview. “The unknown is: Would we feel it’s necessary to do that, would public health officials want this at that point or would they still be comfortable? What we’re trying to do is create an option.”

The success of two remarkably effective coronavirus vaccines in record time last year provided the world some breathing room and hope, even as the pandemic surged. But the detection of both variants late last year caused immediate concern, first because of evidence that they were spreading far more easily. Many of the mutations in each variant — eight of those found in the British variant and 10 of those in the South African variant — drew special concern because they sit in the spiky proteins that dot the outside of the coronavirus and have been the key target for vaccines and therapeutics. That raised the specter that the current generation of vaccines might be rendered obsolete before they have even been fully rolled out.

The company’s announcement puts some of those fears to rest, suggesting that the vaccines will still work against both variants. But the science on vaccines is far from resolved, as was illustrated by the surprising announcement Monday that Merck, a longtime vaccine company, was abandoning its two candidates, finding that both triggered inferior immune responses compared with other vaccines and natural infection.