Pfizer-BioNTech, Moderna and Johnson & Johnson said Monday that they are continuing to develop updated Covid-19 vaccine booster shots that target the omicron variant, which is still spreading rapidly across the globe.
The current versions of the Covid boosters available in the U.S. — the Pfizer and Moderna mRNA formulas and the Johnson & Johnson adenovirus version — are still formulated to target the original form of the virus first identified in China in late 2019.
Research shows those shots still provide adequate protection against the new, super contagious strain, especially against severe disease, hospitalization and death. However, the drugmakers have said they will continue to work on variant-specific boosters in case they are needed.
Pfizer plans to begin human studies for an omicron-specific booster in January, and if all goes as planned, the shot could be ready by March, the company said in a statement to NBC News. Pfizer said it expects to provide an "update" on the next steps for its modified shot later this month.
Moderna CEO Stéphane Bancel said in a CNBC interview that the company's new booster for omicron should be in clinical trials "very soon."
He also said the company is in discussions with public health leaders from around the world about the best strategy for distributing a potential fourth dose later this fall.
"We believe it will contain omicron mRNAs," he said.
Jake Sargent, a spokesperson for Johnson & Johnson, said the company did not have an update on its modified vaccine at this time. Instead, he referred NBC News to a statement from the company in late November when it said it was pursuing an omicron-specific shot and will "progress it as needed."
It’s unclear if omicron-specific shots, or additional doses, will even be necessary by the time they are ready, health experts say.
John Moore, a professor of microbiology and immunology at the Weill Cornell Medical College, said by the time the new shots are ready to be deployed, "omicron will almost certainly have come and gone."
"Omicron infections abroad have spiked up and then back down very rapidly," he said. "In the U.S.A., the present huge surge is likely to be over sometime in February. And omicron is so different that a booster specific for that variant would not work well against the variants we have been more used to."
Dr. Peter Hotez agreed, saying the world will likely be fighting a new global variant by this summer.
Hotez and his colleagues at the Center for Vaccine Development at Texas Children’s Hospital developed a low-cost vaccine, dubbed Corbevax, that was cleared for emergency use in India.
"I think rather than focus on sequence-specific boosters, there’s a need to improve the mRNA technology to make it more durable," he said. "The sharp declines in the effectiveness of Pfizer-BioNTech versus omicron after just a few months creates new challenges."
Dr. Paul Offit, a vaccine expert at the Children’s Hospital of Philadelphia, said the U.S. shouldn't distribute a modified vaccine until a variant emerges that can evade protection against severe illness.
The current shot "has continued to be very successful at protecting against severe disease," he said.
The Food and Drug Administration didn’t have an immediate comment.
Should Americans require additional boosters, the Biden administration would likely need to make arrangements with the drugmakers to ensure supply and on distribution, experts say.
Pfizer has delivered more than 370 million doses of its vaccine to the U.S., according to the Centers for Disease Control and Prevention. Moderna has delivered more than 235 million vaccine doses, and J&J more than 29 million.