Minnesota temporarily suspended use of the Johnson & Johnson COVID-19 vaccine Tuesday while federal authorities investigate whether six unusual blood clots among 7 million U.S. recipients should inhibit its continued use.

The U.S. Centers for Disease Control and Prevention and the U.S. Food and Drug Administration urged the pause because of the rare blood clots found in women 18 to 48 within six to 13 days of being vaccinated.

While the rate of these potential vaccine-related clots appears lower than their general occurrence in the U.S., health authorities said the pause is warranted to alert people to the symptoms and to warn doctors to avoid the use of the common blood thinner heparin to treat them.

"If you experience symptoms including severe headaches, abdominal pain, leg pain or shortness of breath within three weeks of getting Johnson & Johnson vaccine, we want to you to check it out with your health care provider," said state Health Commissioner Jan Malcolm, who received the J&J vaccine March 10.

The six U.S. cases included one death and one person hospitalized in critical condition. None involved people in Minnesota, where at least 184,000 have received J&J shots.

While the single-dose J&J vaccine represented only 5% of the 3.3 million doses administered in Minnesota so far, its supplies were increasing and the suspension will disrupt the state's vaccination progress. Roughly 18,200 doses had been slated for delivery to providers in Minnesota this week through the state and a federal pharmacy contract.

Malcolm said providers would reschedule upcoming appointments, though she expected the pause to last only a few days while federal authorities assess any risks and determine if they outweigh the benefits of J&J vaccine to the population as a whole or specific demographic groups.

A CDC advisory committee will meet Wednesday to review the six adverse events, which involved a type of clot known as cerebral venous sinus thrombosis (CVST) that occurred in combination with low levels of blood platelets. CVST affects the venous sinuses that drain blood from the brain.

"It's their occurrence together that makes a pattern and that pattern is very, very similar to what was seen in Europe with another vaccine," said Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research. "So I think we have to take the time to make sure we understand this complication and we address it properly."

The vaccine in Europe with similar complications is made by AstraZeneca and has not been approved in the U.S. Both use an adenovirus as a vector to deliver the vaccine and produce an immune response, and they work differently from the Pfizer and Moderna COVID-19 vaccines that have not had the same complications.

The clots are distinct from the flu-like symptoms that commonly occur in the day or two after vaccination.

One reason for concern is that common blood clots are often treated with heparin, but that drug can cause "tremendous harm" if used against this combination of CVST with low platelets, Marks said.

Federal officials did not clarify whether the two most severe outcomes among the six cases involved heparin.

The pause did not disrupt the opening of a federally funded vaccine site at the Minnesota State Fairgrounds, which will vaccinate 100,000 people from select ZIP codes in the Twin Cities over the next two months. The site was scheduled to use J&J vaccine in a few weeks, but it started with Pfizer COVID-19 doses and provided shots to 1,500 people by appointment Tuesday.

Gov. Tim Walz toured the pop-up site Tuesday and said he hoped the J&J news wouldn't discourage people or disrupt the state's progress toward a goal of vaccinating 80% of its eligible population. The positivity rate of COVID-19 testing in Minnesota increased to 7.2%, reflecting increased spread of the coronavirus that has caused 6,962 deaths and 545,404 known infections in Minnesota.

The number of Minnesota hospital inpatient beds filled with COVID-19 cases has increased from 210 on March 6 to 676 on Monday.

"As it stands right now in this country, your chance of dying from COVID is 1 in 560. Your chance of having this reaction from the vaccine is 1 in a million," said Walz, who received a J&J dose along with former Gov. Tim Pawlenty on March 30.

While more than 48% of people 16 and older in Minnesota have received COVID-19 vaccine — including 84% of senior citizens at elevated risk of severe illness and death — health officials are worried about hesitancy in those who haven't sought appointments.

Kristina Melville, an Apple Valley woman in her 40s, admitted she felt hesitant Tuesday before becoming one of the first recipients of a Pfizer dose at the fairgrounds.

"Tiny bit, yeah, just because of the unknown," Melville said about the doubt she felt after hearing about the J&J pause. "But the risk is outweighed by the benefit."

Melville was selected for an appointment after registering on the Minnesota Vaccine Connector — just like 24-year-old University of Minnesota graduate student Mandi Lye.

"I'm not a high-risk person. I was like, 'When I get my shot, I get my shot,' " said Lye.

HealthPartners had 500 J&J vaccine appointments put on hold Tuesday and Wednesday but agreed with the pause out of an "abundance of caution," said Dr. Mark Sannes, an infectious disease specialist with the Bloomington-based system.

Dr. Gregory Poland, a vaccine immunology specialist at Mayo Clinic, supported the pause despite the rarity of the clots in vaccinated individuals.

"It's unclear whether this risk is any different from the background rate," he said.

People who have received J&J doses should monitor their health for 30 days.

"Seek medical attention if you have bruising, if you're getting little pinpoint red spots on your extremities, if you're developing an unusual headache, visual loss, abdominal pain that's new, different and persistent," he said. "Basically any new symptom that is noticeably different than what you've had and [is] persistent is a reason to be evaluated."

Staff writer Christopher Snowbeck contributed to this report.