Can asymptomatic carriers spread COVID-19 through blood transfusion?

Can asymptomatic carriers spread COVID-19 through blood transfusion?

Last Reviewed : 12/15/2020
Can asymptomatic carriers spread COVID-19 through blood transfusion?

As COVID-19 cases are rising steeply, it is evident that asymptomatic spread of the infection (infection spreading from the affected people who do not have any symptoms) is playing a bigger role than it was initially thought. More and more cases are being reported to have asymptomatic spread. There is a concern that blood transfusion from an asymptomatic carrier may spread the infection to the blood recipient.

All blood donors are screened for COVID-19 symptoms before donating blood. All donors are also required to call the blood center if they develop fever within one month after donating blood. Donated blood is not routinely tested for COVID-19 before transfused to the recipient.

As per the American Assocation of Blood Bank (AABB) website:

Individuals are not at risk of contracting COVID-19 through the blood donation process or via a blood transfusion, since respiratory viruses are generally not known to be transmitted by donation or transfusion. The U.S. Food and Drug Administration continues to report that there have been no reported or suspected cases of transfusion-transmitted COVID-19 to date. In addition, no cases of transfusion-transmission were ever reported for the other two coronaviruses that emerged during the past two decades (SARS, the Severe Acute Respiratory Syndrome Coronavirus, and MERS-CoV, which causes Mideast Respiratory Syndrome).

However, according to a recent study from the journal of Emerging Infectious Diseases published by the Centers of Disease Control and Prevention (CDC), 4 blood donors were identified in China whose plasma samples tested positive for SARS-CoV-2 RNA. The virus was found in the plasma during routine screening of blood donors, otherwise considered as healthy. They did not have any signs and symptoms of COVID-19 and they all passed the routine screening taken before the blood transfusion.

Finding Novel Coronavirus in the blood of asymptomatic carriers is concerning, especially as donated blood is routinely not tested for COVID-19 before transfused to the recipient. A study published in the journal of Transfusion Medicine Reviews is reassuring and alleviates the above concerns. According to this study, viral RNA could be detected from blood of the infected people with SARS coronavirus, MERS coronavirus or COVID-19. The study mentioned that detection of viral RNA in the blood is not equivalent to the detection of intact infectious virus. It implies that viral particles in the blood may not have the capacity to infect a healthy person. Virus cultures are required to confirm the infectivity; however, they are not easy to perform.

In summary, COVID-19 is probably not transmitted through blood transfusion from asymptomatic carriers. However, CDC and the American Association of Blood Bank are closely monitoring the situation as the asymptomatic spread is more common with COVID-19 when compared to SARS and MERS coronaviruses. Further studies may be needed using virus cultures to get more clarification.




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  2. Lai CC et al. J Microbiol Immunol Infect. 2020 Mar 4. pii: S1684-1182(20)30040-2. doi: 10.1016/j.jmii.2020.02.012. Asymptomatic carrier state, acute respiratory disease, and pneumonia due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2): Facts and myths.
  3. American Association of Blood Bank
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