As misinformation about COVID-19 vaccines spreads, doctors across Canada say some patients are refusing blood transfusions from vaccinated donors, putting their health at risk.

Earlier this month, Calgary-based obstetrician , she had encountered a patient who had declined to receive a blood transfusion unless the blood was from an unvaccinated donor.

"So - this was a first for me. A patient declined blood transfusion if the donor had received a COVID vaccination," she tweeted on Oct. 2. 

Cooper's tweet was met with replies from other physicians who say they've encountered patients making similar requests, including from London, Ont.-based obstetrician , who tweeted, "Sadly, we鈥檝e had a couple of patients here with the same beliefs."

Dr. Davinder Sidhu, the division head for transfusion and transplant medicine for southern Alberta, says he's seen requests for unvaccinated blood "at least once or twice a month over the last several months." In some cases, these concerns have been raised by parents who have heightened concerns over their children.

"Some of the same concerns these parents have about vaccinating their kids, they also have about getting transfusions from COVID-vaccinated folks," he told CTVNews.ca over the phone on Friday. "Our job for those folks is to provide the information, provide our best medical opinion based on the current medical evidence and scientific evidence and walk them through the risks that we know of for sure."

But Sidhu said he's also come across individuals who have declined transfusions from vaccinated donors based on misinformation from dubious sources. Some of these sources incorrectly claim that spike proteins in vaccinated blood could somehow harm recipients or that receiving vaccinated blood could alter patients' DNA.

"Currently, based on the science that we know, there is no increased risk for receiving blood from someone who was vaccinated, or unvaccinated for that matter," Sidhu said.

Canadian Blood Services (CBS) agrees and says such claims are "unproven and not substantiated," citing the rigorous safety studies these vaccines have gone through as well as the ongoing blood safety monitoring in Canada and around the world.

"As part of our mandate to provide a safe, accessible blood supply to Canadians, medical and scientific professionals at Canadian Blood Services carefully review and assess each vaccine approved for use in Canada. Health Canada has not recommended or imposed any restriction on the use of the approved COVID-19 vaccines and blood donation," the agency told CTVNews.ca in a statement on Thursday.

that none of the vaccines approved by Health Canada carry any live pathogens and that the SARS-CoV-2 virus isn't transmissible by blood.

There is also no way to accommodate requests for blood products from unvaccinated donors, given that the COVID-19 vaccination status of donors isn鈥檛 labelled on blood donations. Some patients may request blood specifically from a friend or family member they know is unvaccinated. However, requests for directed donations are almost never granted, given the huge logistical challenges in making sure the right blood goes to the right person.

"We're deviating from all of our routine processes when it comes to selecting blood and blood products. And so actually, the risk for human error and the risk for other complications goes up when we introduce this new complicated factor," Sidhu explained.

Adult patients still have the right to refuse blood transfusions for whatever reason, but this comes with huge risks. While there may be alternatives treatments for some conditions, blood transfusions are often the only solution for those experiencing serious blood loss.

"There's really no alternatives to blood when it comes to oxygen-carrying capacity. And so, if you're having severe bleeds and now you're having cardiac decompensation, or you're having other complications because you're hypovolemic due to blood loss, there's not very many options," Sidhu said.