Drugmaker Moderna has created a new, experimental form of its coronavirus vaccine to combat a worrisome variant of the virus, and has also begun to increase its overall manufacturing capacity, the company announced today.

The new version of the vaccine, directed against a variant first identified in South Africa and now found in the United States and dozens of other countries, has been sent to the National Institutes of Health for testing. Studies have suggested that vaccines may be less effective against this variant than against the form that emerged earlier in the pandemic.

But the new version is probably months away from public use. The company outlined several possible approaches for evaluating the experimental form. Initial test results may be available by summer, Dr. Tal Zaks, Moderna’s chief medical officer, said in an interview.

Moderna’s vaccine uses genetic material called mRNA, a technology that allows researchers to create and adapt vaccines much faster than traditional methods. The Pfizer-BioNTech vaccine is also based on mRNA, and Dr. Ugur Sahin, chief executive of BioNTech, said last month that the company could produce a new version within about six weeks if necessary.

The Food and Drug Administration said Monday that new versions of existing vaccines, adapted to target variants of the coronavirus, would not have to go through the same large trials in 30,000 or 40,000 patients as the first vaccines did.

Moderna said that its original vaccine still provides some protection against the variant, but that “out of an abundance of caution,” the company would pursue several new approaches.

One plan would use a shot of the new vaccine as a booster, after two doses of the original formulation.

Another strategy would be a booster shot combining the new vaccine and the original one.

A third approach, already underway, involves giving a third shot of just the original vaccine as a booster.

These booster shots would use a smaller dose of vaccine, 50 micrograms, instead of the 100 micrograms given in each of the shots now being administered in a two-dose series.

The company said it also planned to evaluate full, 100-microgram doses of the new vaccine and the combination shot as primary vaccinations, rather than merely boosters.

The company also said it was making new capital investments that it expected would enable it to manufacture 1.4 billion doses of coronavirus vaccine in 2022. That figure assumes that a dose is 100 micrograms, but if research finds that smaller amounts are effective, the number of doses would be even higher.

Moderna also said that its production plan for 2021 had increased, to 700 million doses from 600 million, and that it was trying to “potentially deliver up to 1 billion doses in fiscal year 2021.”

The company said it had already shipped 60 million doses globally, including about 55 million to the U.S. government, and expected to complete delivery of the first 100 million U.S. doses by the end of the first quarter of 2021, the second 100 million by the end of May and the third 100 million by the end of July.

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