Johnson & Johnson will allocate 86% fewer doses of its COVID-19 vaccine across the United States next week than are currently being allocated, according to data provided by the Centers for Disease Control and Prevention, just as the national vaccination campaign has found its footing.

Distribution of the single-shot vaccine has been inconsistent since Johnson & Johnson delivered its first batch at the beginning of March, sending 2.8 million doses across the country before dipping below 400,000 in the following weeks.

Last week, about 1.9 million doses were sent across the country. This week 4.9 million doses went out. But next week, that number will drop to just 700,000.

Federal administrators divide vaccine doses nationwide based on each state’s adult population. That means California will bear the brunt of the reduction: After receiving 572,700 doses of the Johnson & Johnson vaccine this week, it will only get only 67,600 next week.

In Texas, the allocation will drop to 46,300 from 392,100; Florida, which received 313,200 doses this week, will get 37,000 next week. Guam, which received 16,900 doses this week, will receive none next week.

The slowdown comes days after federal officials learned that Emergent BioSolutions, a contract manufacturer that has been making both the Johnson & Johnson and the AstraZeneca vaccines, mixed up ingredients from the two, ruining up to 15 million doses of the Johnson & Johnson vaccine.

That mix-up led regulators to delay authorization of the plant’s production lines and the Biden administration to put Johnson & Johnson in charge of the troubled Baltimore plant.

How big a role the problems at the Baltimore factory are playing in the fluctuations in the Johnson & Johnson vaccine distribution is still difficult to determine.

Conservative about how many doses it would produce at first, Johnson & Johnson still fell behind this winter on its production goals in the U.S., delivering less than it had promised in February and March.

The initial Johnson & Johnson vaccine supply allocated in the United States came from a Dutch plant, and it was delivered on an uneven schedule. That led the Biden administration to warn state health officials that the supply of the vaccine would be variable.

But federal officials expected that with the help of the Emergent factory in Baltimore, there would be a steady stream of doses from the company in April. Now, with that plant still lacking authorization, the anticipated delivery schedule of the vaccine is up in the air.

In Maryland, the state health secretary, Dennis Schrader, told vaccine providers that the “significant decrease with no advance notice is a surprise and a disappointment, and we share your frustration.” The state will receive 78,300 fewer doses next week compared with this week.

In Ohio, speaking at his weekly news conference, Gov. Mike DeWine said he had been told that the reduction in doses was not a result of “what happened in the factory.” Ohio is to receive 151,600 fewer shots next week.

The CDC said Thursday that about 112 million people in the United States had received at least one dose of a vaccine, including about 66.2 million people who have been fully vaccinated by Johnson & Johnson’s single-dose vaccine or the two-dose series made by Pfizer-BioNTech and Moderna.

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