The antibody cocktail President Donald Trump credited for his swift coronavirus recovery won’t become widely available because it’s impossible to make enough for everyone who might need it, according to the Swiss pharmaceutical giant working on scaling up production.

"We'll never be able to produce enough," said Bill Anderson, drugs chief at Roche Holding, which is working with U.S. biotech Regeneron Pharmaceuticals on the project. "This is clearly part of the answer for the world, not the answer. Hopefully we'll have vaccines and other therapeutics."

The partners will probably be able to make as many as 2 million doses per year by the end of next March if the drug cocktail wins regulatory approval, Anderson said. That's about the number of new covid-19 cases identified worldwide in the past week.

The need for a multipronged approach to treat the virus has come into focus as potential safety issues emerge in late-stage trials of some promising vaccines and treatments. Eli Lilly & Co. this week paused a study of its own covid-19 antibody to investigate such a concern.

Roche on Thursday reported third-quarter sales that fell short of estimates after a one-two punch: older prescription drugs faced a challenge from cheaper copycats while the pandemic continued to discourage some patients from seeing their doctors. The stock fell as much as 3.6% in Zurich trading.

The U.S. has already secured hundreds of thousands of doses of experimental antibody treatments, federal health officials said earlier this month, before the Lilly trial was paused. At that point they expected to have 1 million doses on hand by the end of the year.

Trump touted Regeneron's antibody cocktail as a cure and key to his recovery, saying he would make the drugs he took available free to Americans. Regeneron has asked federal regulators for emergency clearance to sell the treatment. Though the drug had promising early results, the large clinical trials to test its safety and efficacy haven't finished yet.

Production capacity is limited in part because the antibody doses being studied for covid-19 are so much bigger than for other diseases, according to Roche’s Anderson. For example, the low dose being evaluated in Regeneron’s trial, 2.4 grams, is about as much antibody as is used to treat a breast-cancer patient for four to six months or a person with multiple sclerosis for two years, he said.