At least 36 people have developed a rare blood disorder called thrombocytopenia after receiving either the Pfizer and BioNTech or Moderna's COVID-19 vaccines, according to a report by The New York Times.

Thrombocytopenia usually happens when the immune system attacks platelets which are cell fragments that help blood clot.

One of the individuals affected by the condition was Miami obstetrician Gregory Smith, 56, who died after thrombocytopenia caused his platelets to drop to virtually zero. Symptoms reportedly appeared three days after he received the Pfizer-BioNTech shot on Dec. 18.

Luz Legaspi, 72,  was hospitalized in New York City on Jan. 19 after waking up with bruises on her arms and legs and blisters that bled inside her mouth just one day after receiving her first dose of Moderna's COVID-19 vaccine.

The report said Legaspi's platelet count was zero and doctors ordered her to not leave her bed for over a week, for fear a bump, bruise, fall, or other minor injury could lead to a similar hemorrhage that could be fatal for her. 

Legaspi reportedly received the platelet treatments but was not showing signs of improvement after 10 days in the hospital.

Officials with the Food and Drug Administration and the Centers for Disease Control and Prevention said that they were looking into the reports but added that rates of the condition in vaccinated people did not appear higher than the rates normally found in the US population, so the cases could also be coincidental, the report said.

Pfizer, meanwhile, released a statement saying it “take reports of adverse events very seriously,” and added that it was aware of thrombocytopenia cases in vaccine recipients.

Moderna said it continuously monitors the safety of the Moderna COVID-19 vaccine using all sources of data” and routinely shares safety information with regulators. It did not address the question of the platelet disorder.

Pfizer and Moderna are the  authorized vaccines so far for emergency use in the United States.

Hematologists with expertise in treating immune thrombocytopenia said they suspected that the vaccine did play a role, the report added.

It also said that platelet-suppressing condition appears exceedingly rare and is probably due to an unknown predisposition that could lead vaccines to trigger the blood disorder. The disorder has occurred, rarely, in people who received other inoculations, particularly the measles-mumps-rubella one.

“I think it is possible that there is an association. I’m assuming there’s something that made the people who developed thrombocytopenia susceptible, given what a tiny percentage of recipients they are,” Dr. James Bussel, a hematologist and professor emeritus at Weill Cornell Medicine said.

Over 27 million Americans have been infected and more than 468,000 Americans have died due to COVID-19 since the pandemic began in March, according to Johns Hopkins University.