By Peter Loftus

Deliveries of Johnson & Johnson's Covid-19 vaccine doses throughout the U.S. are expected to plunge by more than 80% next week, according to state officials and federal data, as J&J grapples with manufacturing challenges.

The federal government has allocated just 700,000 doses of J&J's vaccine to U.S. states, territories and certain cities and federal agencies next week, compared with 4.9 million doses that were allocated for this week, according to information posted online by the Centers for Disease Control and Prevention.

The expected sharp decrease will complicate states officials' mass vaccination plans at a time when they're counting on a greater supply of doses to help immunize the growing number of people becoming eligible.

It isn't clear why next week's supply is decreasing so sharply, though federal officials have cautioned states there could be fluctuations week to week.

J&J recently experienced a production problem at a contract manufacturer's plant in Baltimore--a factor cited by some state officials--but that plant hasn't been authorized by U.S. regulators to supply doses for the U.S.

J&J, of New Brunswick, N.J., has been making the vaccine's main ingredient at its own plant in the Netherlands, which has supplied the doses distributed in the U.S. since the vaccine was authorized by regulators in late February.

A J&J spokesman declined to comment on next week's supply, but said the company still aims to deliver 100 million doses for U.S. use by mid-year, and possibly most of that by the end of May. J&J also is working with U.S. regulators toward the authorization of the contract manufacturing plant in Baltimore, the spokesman said.

J&J's vaccine was the third Covid-19 shot authorized in the U.S., after vaccines from Pfizer Inc. with its partner BioNTech SE and Moderna Inc. were cleared in December. Health officials were counting on its arrival to jump-start the effort to vaccinate much of the U.S. population and help bring the coronavirus pandemic under control.

Millions of doses of the Pfizer and Moderna vaccines are still expected next week, but state officials said the decline in J&J vaccine doses could result in fewer appointment slots for vaccinations and cause delays in plans to target certain populations with the J&J vaccine.

"It definitely is way lower than what we were expecting," Dr. Danny Avula, Virginia's state vaccine coordinator, said in an interview. "It's just going to take longer for those who want a vaccine to be able to get vaccinated."

Virginia is planning to widen eligibility for the Covid-19 vaccine to everyone 16 and older on April 18, in line with President Biden's recent call for all U.S. adults to be eligible by April 19. Virginia, like other states, initially reserved vaccines for health-care workers, the elderly and other priority groups.

But Virginia may have to scale back and delay the start of vaccination clinics planned for college campuses using J&J's single-dose vaccine, Dr. Avula said. The state was hoping to start vaccinating students on most campuses next week, but now may have to limit them to a handful of campuses next week and delay them for others. Its allotment of the J&J vaccine for next week is 14,800 doses, down from more than 124,000 doses this week.

The J&J vaccine is ideal for college students who will soon return home at the end of the spring semester because it's a single dose, unlike the shots from Pfizer and Moderna which require a second three or weeks after the first, Dr. Avula said.

New Jersey Gov. Phil Murphy said in a press conference Thursday the expected decline in J&J doses means "there are available appointments now that are probably not going to be available next week." The state's allocation of J&J's vaccine is falling to 15,600 doses next week from more than 131,000 this week.

Washington State is due to receive 12,900 doses of J&J's vaccine next week, down from more than 100,000 allotted to the state this week. The state's allotment could fall even more for the week of April 19, to 5,000 doses, SheAnne Allen, Covid-19 vaccine director for the Washington State Department of Health, said during an online briefing Wednesday.

J&J delivered to the U.S. government a total of 20 million doses by the end of March, and has said it would deliver an additional 24 million doses by the end of April.

But its efforts to expand production to a contractor's plant in Baltimore have been marred by setbacks. A batch of the main ingredient manufactured at Emergent BioSolutions Inc.'s factory was ruined because it didn't meet quality standards, and no doses were distributed from it.

J&J recently sent additional employees to assume full responsibility for making the vaccine's main ingredient at the Emergent plant, a move that also involved relocating production of AstraZeneca PLC's Covid-19 vaccine from the same plant.

--Jon Kamp contributed to this article.

Write to Peter Loftus at peter.loftus@wsj.com

(END) Dow Jones Newswires

04-09-21 0824ET