COVID-19: Further evidence of no transfusion transmission.

To the editor,

SARS-CoV-2 pandemic had a huge impact on transfusion services, mostly due to the shortage of blood donors during periods of intense social isolation and the implementation of plasma convalescent protocol, requiring the fast and efficient recruitment of immunized donors for apheresis donation. Due to the fact that the SARS-CoV-2 transfusion transmission risks have never been mitigated, mostly due to the lack of studies specifically designed to address this question, blood centers had to deal with the risks of asymptomatic contaminated donors without knowing the disease risk for the recipients.

To date, transfusion transmission of any respiratory virus, including SARS-CoV and the Middle East Respiratory Syndrome (MERS)-CoV, has never been confirmed. Two recent studies evaluated the risks of transmission via blood transfusion of SARS-CoV-2. One has determined that there is no risk of RNA-emia in asymptomatic blood donors, but the sample size was very low [1]. The other study followed-up recipients of blood products of seven donors who tested positive for SARS-CoV-2 infection 6–15 days following the donation and documented that none developed SARS-CoV-2-related symptoms [2]. Similarly, one study has reported the case of an adult donor of hematopoietic stem cells who was in the incubation period of SARS-CoV-2 infection at the moment of the collection and the recipient had no laboratorial or clinical evidences of infection [3].

In our service, we had 5 donors who experienced COVID-19 symptoms after donation whose blood products have already been transfused to patients. The time between the donation and the COVID-19-related symptoms varied from 1 to 8 days. Two donors had the COVID-19 diagnosis confirmed by PCR, while 2 confirmed the infection through anti-SARS-CoV-2 immunoassays and 2 had presumptive diagnosis. There were 9 blood products derived from the donations: 6 platelet units, 1 red blood cell unit and 2 granulocyte concentrates. All but one of the 9 recipients were immunosuppressed and none presented COVID-19 related symptoms after the transfusions. Interestingly, one recipient with acute lymphoblastic leukemia was transfused with two granulocytes concentrates stemming from two donors with COVID-19 in the incubation period. This patient was critically ill, but the clinical symptoms have not worsened after the transfusion and COVID-19 RT-PCR was negative in the follow-up. Table1 displays a summary of the donors and patients evaluated in this study.

Table 1

Summary of the evaluation of the donors exhibiting COVID-19 symptoms and the follow-up of the involved transfused patients.

Donor ID	Recipient ID	Time between donation and transfusion	Time between donation and donor COVID-related symptoms	Time between donation and donor positive RT-PCR	Transfused blood product	Characteristics of the transfusion recipient	Post-transfusion follow-up
1	1	5 days	5 days	5 days	Platelets	8 years-old	No fever or other COVID19-related symptoms
						Acute lymphoblastic leukemia (All)	Improvement of clinical symptoms
						D+7post allogeneic hematopoietic stem cell transplantation [HSCT)
						Vaso-occlusive disease (VOD)
	2	4 days	5 days	5 days	Platelets	1 year-old	No fever or other COVID 19-related symptoms
						Neurologic and Pulmonary tuberculosis	Improvement of clinical symptoms
						Citomegalovirus infection
	3	4 days	5 days	5 days	Platelets	68 years-old	No fever or other COVID 19-related symptoms
						Mantle lymphoma on chemotherapy
2	4	2days	1 days	Presumptive. diagnosis	Platelets	13 years-old	No fever or other COVID 19-related symptoms
						Acute lymphoblastic leukemia	Death I Month later
						Chronic Intestinal Graft versus Host Diseases
	5	2days	1 days	Presumptive. Diagnosis	Platelets	8 years-old	No fever or other COVID 19-related symptoms
						Aplastic Anemia	Improvement of clinical symptoms
						Chronic Intestinal Graft versus Host Diseases
3	6	4 days	1 days	1 days	Whole Blood	2 years-old	No fever or other COVID 19-related symptoms
						End-stage renal disease
4	7	Same days	7 days	Diagnosis confirmed by serology	Granulocytes	5 years-old	The patient presented episodes of fever daily, even before the transfusion
				14 days after begginning of symptoms		Acute lymphoblastic leukemia	No fever or other COVID 19-related symptoms
						Fournier syndrome and sepsis
5	7	Same days	1 days	Diagnosis confirmed by serology	Granulocytes	5 years-old	The patient presented episodes of fever daily, even before the transfusion
				14 days after begginning of symptoms		Acute lymphoblastic leukemia	No fever or other COVID 19-related symptoms
						Fournier syndrome and sepsis
5	8	2 days	8 days	Diagnosis confirmed by serology	Platelets	27 years-old	No fever or other COVID 19-related symptoms
				14 days after begginning of symptoms		Biphenotypic leukemia	Improvement of clinical symptoms
						Induction Chemotherapy

In sum, we provide here further evidence that SARS-CoV-2 infection is not transfusion-transmitted. This is very important information for transfusion services, as sheds light to the fact that testing blood donors with immunoassays to detect anti-SARS-CoV-2 antibodies is not recommended unless the goal is to provide an epidemiological overview of the infection.

Funding

No funding to declare.

Declaration of Competing Interest

The authors report no declarations of interest.