As a precaution, Moderna announced it will launch two new studies. The company will test adding a third shot of its current vaccine to boost its two-dose regimen. Scientists have also already designed an all-new vaccine specific to the South African variant that could be used as a booster to prime the immune system to the new strain, and plan to test it in the coming months.
“The virus is changing its stripes, and we will change to make sure we can beat the virus where it’s going,” Stephen Hoge, president of Moderna, 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 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 triggered immediate concern, first because of evidence 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 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 veteran vaccine company, was abandoning its two candidates, finding both triggered inferior immune responses compared with other vaccines and natural infection.
Late last year, Sanofi and GlaxoSmithKline announced they were redesigning their vaccine after a first version failed to trigger a robust immune response in older adults and didn’t expect their candidate would be available until the end of the year.
In the Moderna study, antibody-containing blood serum taken from people and monkeys who received the vaccine showed it was just as effective at blocking the British variant as the original strain of virus in the study. And it remained above the threshold for efficacy for the South African variant, despite the diminution in effectiveness. The work has been submitted to a preprint server, but has not been peer-reviewed and was not available for review before publication.
The company reported a sixfold decrease in the ability of antibodies to block the South African variant — a drop that Hoge said was concerning but not alarming — underscoring the need to remain vigilant.
The report comes after similar news from Pfizer-BioNTech, which released data last week that also was not yet peer-reviewed. Pfizer found that antibody-rich blood serum samples from 16 vaccinated people showed that vaccine was equally as effective at blocking the British variant as it was against the original version of the virus that took hold in Wuhan, China, a year ago. That publication did not address the South African variant, which has been of most concern and shares many mutations with a concerning variant detected in Brazil.
Laboratories across the world have been scrambling to study whether vaccines and treatments, particularly monoclonal antibodies, are likely to be as effective against the new variants. So far, such tests have mainly relied on one part of the multifaceted immune response and found evidence the vaccines are likely to be effective. But those tests have underscored the need to track changes in the virus and prepare for the eventuality that, like flu shots, a coronavirus vaccine might need to be updated and administered on a regular basis.