US regulators revoked emergency authorization for Johnson & Johnson’s Covid-19 vaccine after the company’s Janssen unit requested its withdrawal.

Janssen informed the Food and Drug Administration that shots bought by the government had expired and there was no demand for the product in the US, the regulator said in a statement released last week.

“FDA has determined that it is appropriate to protect the public health or safety to revoke this authorization,” according to the statement. The company “does not intend to update the strain composition of this vaccine to address emerging variants.”

J&J’s single-dose vaccine faced problems early on following manufacturing hiccups and cases of a rare and potentially deadly clotting disorder slowed its roll out in early 2021. Demand has since remained subdued compared with more popular shots from Moderna Inc. and the partnership of Pfizer Inc. and BioNTech SE.

The decision shouldn’t affect people who’ve received Janssen’s shot as part of their Covid vaccine regimen, according to Joshua Sharfstein, dean for public health practice and community engagement at Johns Hopkins Bloomberg School of Public Health.

“Since the reason for the withdrawal does not have to do with the effectiveness of the vaccine, I would not expect it to change whether the vaccine counts for someone’s protection,” he said.