UPDATE 4-Emergent to resume J&J COVID-19 vaccine production at Baltimore plant

(Adds comment from Emergent's Thursday earnings call)

July 29 (Reuters) - Emergent BioSolutions said it will resume production of Johnson & Johnson's COVID-19 vaccine at its troubled Baltimore facility, where operations were stopped in April after millions of doses were found to be contaminated.

The development was announced late on Wednesday. Last week, J&J slashed 2021 production target of its single-dose vaccine to between 500 million and 600 million doses from its original goal to produce a billion shots.

The resumption follows additional reviews and collaboration with the FDA and manufacturing partners, Emergent Chief Executive Officer Robert Kramer said.

The FDA has so far approved five batches from the Emergent facility since production there was paused, and J&J is working to clear additional doses for use, the drugmaker said last week.

Emergent expects the FDA to approve additional batches of J&J shots, Kramer said during Emergent's Thursday investor call.

U.S. health regulators in April halted operations at the Baltimore plant following a discovery that ingredients from AstraZeneca's COVID-19 vaccine, also being produced there at that time, contaminated a batch of J&J's vaccines.

That month, the U.S. government asked Emergent to stop making AstraZeneca shots after it discovered the cross contamination.

"We continue to work collaboratively with AstraZeneca to complete all documents related to their drug substance so they and the U.S. government can make decisions regarding the disposition of this material," Kramer said during the call.

An FDA inspection also turned up a long list of sanitary problems and bad manufacturing practices.

J&J's vaccine, considered more convenient for use, storing and shipping to remote areas, has seen a relatively slow uptake in Europe and the United States due to safety concerns and the production issues.

"We will continue to work toward securing Emergency Use Authorization in the United States for drug substance manufactured at Emergent Bayview as quickly as possible," J&J said in an email.

The FDA did not immediately respond to a Reuters request for comment.

The Wall Street Journal, which first reported the news, cited a letter from the FDA saying the agency had no objections with the plant resuming manufacturing. (https://on.wsj.com/3iXSAfg)

The facility could make as many as 120 million doses a month at full capacity, but the finished doses might not be available until this fall, the Journal reported.

Emergent expects to launch in the near future a late stage study for a COVID-19 therapeutic it is developing in partnership with the U.S. government, executives said on the investor call. (Reporting by Aishwarya Nair, Maria Ponnezhath and Manojna Maddipatla in Bengaluru; Editing by Subhranshu Sahu, Ramakrishnan M. and Shounak Dasgupta)