U.S. Blood Supply Safe Despite COVID-19 Pandemic

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Each year, millions of Americans volunteer to donate units of blood to help patients who may need blood transfusions during surgeries or for treatment of diseases. Prospective blood donors routinely undergo a screening process to help ensure that infectious diseases are not spread through their blood donations. Results of a large study conducted by National Institutes of Health (NIH) scientists have found that, despite the COVID-19 pandemic, the screening process has ensured the safety of the nation’s blood supply. Results of the study were published May 27, 2021 in Transfusion.

SARS-CoV-2 is a respiratory virus that is primarily spread through the air when an infected person coughs or sneezes, releasing contaminated droplets that can then be breathed in by other people in the same area. While this is the primary way the virus is spread, the NIH researchers conducted a study to determine if SARS-CoV-2 could be found in the blood of healthy donors who had no symptoms of infection, and could potentially spread the virus to blood recipients.

Under current guidelines, blood donation center lab personnel do not test donated blood for the presence of SARS-CoV-2. Prospective blood donors are allowed to donate only if they have no COVID-19 symptoms and have not had an infection within the last 14 days. However, some people may have COVID-19 but show no symptoms, or may have recovered from COVID-19 but still have small amounts of the virus within their bodies. To determine if these scenarios would put the nation’s blood supply at risk, the NIH researchers began testing blood samples from various blood donation centers across the U.S.

For the study, researchers used very sensitive molecular tests (nucleic acid amplification tests) to detect the presence of SARS-CoV-2 genetic material (RNA) in nearly 18,000 pools of donated blood. The pooled donations came from over 250,000 single blood donations collected in six large U.S. metropolitan areas from March 2020 to September 2020.

Out of the thousands of pooled donations tested, just three returned positive results for the virus, and the amount of virus present was found to be at very low levels. Given these data, the researchers concluded that the chance that a transfusion recipient would receive blood with very low virus levels is about 1 in 100,000. The scientists further concluded that the risk of SARS-CoV-2 transmission through a blood transfusion is negligible compared to virus transmission through the air.

These conclusions support the considerations from the U.S. Food and Drug Administration (FDA) on the eligibility of blood donors. The FDA has stated that “respiratory viruses, in general, are not known to be transmitted by blood transfusion. There have been no reported cases of transfusion-transmitted coronavirus, including SARS-CoV-2, worldwide.”

“This finding is good news for thousands of patients who may need a blood transfusion because of surgery or a disease that causes anemia, such as a rare blood-related condition or leukemia,” said Simone Glynn, MD, MPH, chief of NIH’s Blood Epidemiology and Clinical Therapeutics Branch in a press release.

Researchers in other countries around the world such as France, China, Pakistan and Korea have conducted similar studies and those results substantiate the U.S. findings. While SARS-CoV-2 was rarely found in donated blood, the level of virus present was very low and did not result in the spread of COVID-19.

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Sources and Resources


Bakkour S, et al. Minipool testing for SARS-CoV-2 RNA in United States blood donors. May 27, 2021. Accessed June 9, 2021 at https://doi.org/10.1111/trf.16511

(June 1, 2021) U.S. blood donations are safe under current COVID-19 screening guidelines. National Institutes of Health press release. Accessed June 9, 2021 at https://www.nih.gov/news-events/news-releases/us-blood-donations-are-safe-under-current-covid-19-screening-guidelines

(June 1, 2021) NIH Study: Current Donor Screening Practices Protect Blood Supply Against SARS-CoV-2. Accessed June 10, 2021 at https://www.aabb.org/news-resources/news/article/2021/06/01/nih-study-current-donor-screening-practices-protect-blood-supply-against-sars-cov-2

(January 19, 2021) Updated Information for Blood Establishments Regarding the COVID-19 Pandemic and Blood Donation. U.S. Food and Drug Administration. Accessed June 10, 2021 at https://www.fda.gov/vaccines-blood-biologics/safety-availability-biologics/updated-information-blood-establishments-regarding-covid-19-pandemic-and-blood-donation