The Rhode Island Department of Health announced Tuesday that it is following the federal government's recommendation to “pause” the administration of the single-dose Johnson & Johnson COVID-19 vaccine to investigate reports in other parts of the country of potentially dangerous blood clots.

More than 31,500 shots of the single-dose Johnson & Johnson vaccine have been administered in Rhode Island, but state health officials said they have received no reports that the vaccine “represents a health or safety concern.’’ However, they said, Rhode Island “is taking this step in alignment with federal partners.”

No appointments for Johnson & Johnson vaccinations had been scheduled for Tuesday, the department said. State health officials are directing vaccinators that made Johnson & Johnson vaccination appointments not to administer those doses.

Rhode Island health officials say they have enough supply of the two-shot Moderna and Pfizer vaccines to cover residents who were scheduled to receive the Johnson & Johnson shots. People who have been scheduled for appointments for the Johnson & Johnson vaccine will be given either the Moderna or Pfizer vaccine at their scheduled appointments, Joseph Wendelken, a health department spokesman, said in an email. No additional action on the part of those with appointments is required, he said.

About 300 Rhode Islanders who have appointments at clinics which only offer the Johnson & Johnson vaccines -- Green Line Apothecary, White Cross Pharmacy and the Rhode Island Free Clinic -- will be called about rescheduling their appointments, Thomas McCarthy, executive director of the Health Department’s COVID Response, said during a briefing Tuesday.  

Rhode Island health health officials tried to put the risk of the Johnson & Johnson vaccine into perspective, pointing out that of the more than 6.8 million who received the vaccine in the U.S., six experienced the potentially dangerous blood clots within 13 days of being vaccinated. That means the risk of less than one in a million. 

“So if you were vaccinated with the Johnson & Johnson vaccine more than a month ago... your risk is extremely low,’’ Dr. Nicole Alexander-Scott, the state health director, said at the briefing. “If you have been vaccinated with Johnson & Johnson vaccine in the last three weeks, your risk is also very low.’’

The decision to pause use of the Johnson & Johnson COVID-19 vaccines has not changed the state’s vaccination timeline -- at least not yet.  The timetable, announced last week, includes having 70% of residents 16 and older vaccinated by May 15. Health officials said they expect 70% of all residents to have had at least one dose by June 5.

“If this pause is prolonged," McCarthy said, "we'll reassess.’’

Johnson & Johnson has provided less than five percent (5%) of all the vaccine doses allocated to Rhode Island, McCarthy said. Rhode Island was scheduled to receive 2,000 Johnson & Johnson doses this week, he said, compared with 6,000 last week. They state also has 1,400 doses leftover from last week, he said.  But the supply is scheduled to increase again in May to about 16,000 doses per week, he said, as the company ramps up production.    

By contrast, Rhode Island’s weekly allotment of the two-shot vaccines from Pfizer and Moderna, McCarthy said, is about 70,000 doses. That represents more than 80% of the 85,000 doses he said the state has administered during the last two weeks.

The impact of pausing the use of the Johnson & Johnson vaccines on the vaccination timelines will depend in part on how long the federal investigation of the medication takes.

In a joint statement Tuesday, the Centers for Disease Control and Prevention and the Food and Drug Administration said they were investigating clots in six women that occurred 6 to 13 days after vaccination. The clots were observed in the sinuses of the brain along with reduced platelet counts — making the usual treatment for blood clots, the blood thinner heparin, potentially “dangerous.”

More than 6.8 million doses of the J&J vaccine have been administered in the U.S., the vast majority with no or mild side effects.

U.S. federal distribution channels, including mass vaccination sites, will pause the use of the J&J shot, and states and other providers are expected to follow.

The CDC’s Advisory Committee on Immunization Practices will meet Wednesday to discuss the cases and the FDA has also launched an investigation into the cause of the clots and low platelet counts.

“Until that process is complete, we are recommending a pause in the use of this vaccine out of an abundance of caution,” Dr. Anne Schuchat, principal deputy director of the CDC, and Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said in a joint statement.

They are recommending that people who were given the J&J vaccine who are experiencing severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after receiving the shot contact their health care provider.

Officials say they also want to educate vaccine providers and health professionals about the “unique treatment” required for this type of clot.

Johnson & Johnson said it was aware of the reports of “thromboembolic events,” or blood clots, but that no link to its vaccine had been established.

“We are aware that thromboembolic events including those with thrombocytopenia have been reported with Covid-19 vaccines,” said Johnson & Johnson in a statement. “At present, no clear causal relationship has been established between these rare events and the Janssen Covid-19 vaccine.”

The J&J vaccine received emergency use authorization from the FDA in late February with great fanfare, with hopes that its single-dose and relatively simple storage requirements would speed vaccinations across the country. Yet the shot only makes up a small fraction of the doses administered in the U.S. as J&J has been plagued by production delays and manufacturing errors at the Baltimore plant of a contractor.

Last week the drugmaker took over the facility to scale up production in hopes of meeting its commitment to the U.S. government of providing about 100 million doses by the end of May.

Only about 9 million of the company’s doses have been delivered to states and are awaiting administration, according to CDC data.

Until now concern about the unusual blood clots has centered on the vaccine from AstraZeneca, which has not yet received authorization in the U.S. Last week, European regulators said they found a possible link between the shots and a very rare type of blood clot that occurs together with low blood platelets, one that seems to occur more in younger people.

updated 12:10 p.m.

-- Health reporter Lynn Arditi can be reached at Follow her on Twitter @LynnArditi.

-with reports by the Associated Press