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COVID-19 vaccines do not change color of blood

September 20, 2021 GMT

CLAIM: Photo shows a bag of red blood from an unvaccinated individual and a bag of darker red blood from a person who has received the COVID-19 vaccine.

AP’S ASSESSMENT: False. COVID-19 vaccines do not change the color of blood.

THE FACTS: A photo purporting to show two bags full of differently colored blood is circulating online this week with a caption suggesting that it shows that the COVID-19 vaccines are changing the color of blood to a purplish hue.

The post claims that medical professionals are noticing this change but no one is speaking up about it. It’s unclear where the image originated or what it shows.

More than 200 million Americans have received at least one shot of a COVID-19 vaccine, and laboratories and blood banks have seen no such change in blood. Also, blood changing color would have been reported during the clinical trials for the vaccine when blood was being tested for antibodies, said Dr. William Schaffner, an infectious disease expert at Vanderbilt University.

“’The color of blood has remained the same as always,” he said.

Dr. Stephanie Halene, chief of hematology at the Yale Cancer Center, was not surprised at the different colors of the bags in the photo. Halene said the color of blood can vary depending on the level of oxygen in it. Oxygenated blood appears bright red, while deoxygenated blood is a deeper, purplish tone.

The American Red Cross has continued to collect blood donations following the vaccination of millions of Americans against COVID-19. The organization said in a statement that they visually inspect all donated units of blood and they have not seen the change in color that the post described.

The Association of Public Health Laboratories, an organization that represents state and local health labs, also confirmed to the AP in an email that its staff have not had any reports of the phenomenon claimed in the post.

A similar claim originated at the start of the pandemic in 2020 that said the virus changed the color of blood to purple. Experts refuted that claim.


This is part of AP’s effort to address widely shared misinformation, including work with outside companies and organizations to add factual context to misleading content that is circulating online. Learn more about fact-checking at AP.