An investigation into the vaccine uncovered 15 recipients who developed a highly unusual kind of blood clot out of almost 8 million people given the J&J shot.
The pause came at an inconvenient time for Allen County Public Health, which had recently started a mass vaccination effort at the former Knights of Columbus Hall that relied on the single-dose shot to inoculate hundreds of people per day.
The independent body of scientific experts declared the Janssen COVID-19 vaccine by Johnson & Johnson safe for use, saying the benefits of preventing COVID-19 infection outweigh the risk of rare blood clots.
Johnson & Johnson's one-dose vaccine returned to the large-scale vaccination clinic in Worcester this week.
"As the COVID-19 epidemic in Denmark is now under control, and the vaccination rollout is progressing satisfactorily with other available vaccines, the Danish Health Authority has chose to continue the national vaccination campaign without the COVID-19 vaccine from Johnson & Johnson".
But it acknowledged that the decision would delay the vaccination campaign.
Denmark has already taken the AstraZeneca shot out of its vaccination program for the same reason. The supply now isn't voluminous, as Saint Vincent Hospital predicts about one or two more clinics will use the remaining single-shot doses.
"New knowledge may emerge, or the situation in Denmark may change, for example, in terms of infection pressure, disease burden, epidemic control, or other vaccines' availability", the health authority said.
In a statement to national media, the health agency indicated that the freeze affects 300,000 doses received during the past week, with the doses to be reviewed before they can be distributed.
Now there are four vaccines approved for use in the EU: Pfizer-BioNTech, Moderna, AstraZeneca and Johnson & Johnson - the latter two reserved for older people in most European countries.
In Canada there have been seven known cases of vaccine-induced thrombotic thrombocytopenia, or VITT, one of them fatal.