The announcement arrived at a critical moment, as the steep decline in coronavirus cases seems to have plateaued and millions of Americans are on waiting lists for shots.
Johnson & Johnson has pledged to provide the United States with 100 million doses by the end of June. When combined with the 600 million doses from the two-shot vaccines made by Pfizer-BioNTech and Moderna scheduled to arrive by the end of July, there will be more than enough shots to cover any American adult who wants one.
But federal and state health officials are concerned that even with strong data to support it, some people may perceive Johnson & Johnson’s shot as an inferior option.
The new vaccine’s 72 percent efficacy rate in the U.S. clinical trial site — a number scientists have celebrated — falls short of the roughly 95 percent rate found in studies testing the Moderna and Pfizer-BioNTech vaccines. Across all trial sites, the Johnson & Johnson vaccine also showed 85 percent efficacy against severe forms of Covid-19 and 100 percent efficacy against hospitalization and death from the virus.
“Don’t get caught up, necessarily, on the number game, because it’s a really good vaccine, and what we need is as many good vaccines as possible,” Dr. Anthony S. Fauci, the government’s top infectious disease expert, said in an interview on Saturday. “Rather than parsing the difference between 94 and 72, accept the fact that now you have three highly effective vaccines. Period.”
If Johnson & Johnson’s vaccine would have been the first to be authorized in the United States instead of the third, “everybody would be doing handstands and back flips and high-fives,” said Dr. James T. McDeavitt, dean of clinical affairs at the Baylor College of Medicine.
Johnson & Johnson has said it will ship nearly four million doses as soon as the F.D.A. authorizes distribution and another 16 million or so doses by the end of March. That is far fewer than the 37 million doses called for in its $1 billion federal contract, but the contract says that deliveries that are 30 days late will still be considered timely.
The federal government is paying the firm $10 a dose for a total of 100 million doses to be ready by the end of June, substantially less per dose than it agreed to pay Moderna and Pfizer.
Johnson & Johnson’s one-dose vaccine might allow states to rapidly increase the number of people who have been fully inoculated. Unlike the other two vaccines, it can be stored at standard refrigeration temperatures for at least three months.