Serologic testing of U.S. blood donations to identify SARS-CoV-2-reactive antibodies: December 2019-January 2020

The study “Serologic testing of U.S. blood donations to identify SARS-CoV-2-reactive antibodies: December 2019-January 2020” provides compelling insights into the early presence of COVID-19 in the United States.

Here’s a detailed summary:

Background: Initially identified in Wuhan, China, in December 2019, SARS-CoV-2, the virus causing COVID-19, spread globally with the first U.S. cases reported in January 2020. However, some evidence suggested the virus might have entered the U.S. earlier than recognized​​.

Study Objective: The study aimed to determine if SARS-CoV-2 reactive antibodies were present in blood donations before the first U.S. case was officially identified on January 19, 2020. Researchers analyzed 7,389 archived blood donation samples from the American Red Cross, collected between December 13, 2019, and January 17, 2020, from nine U.S. states​​.

Methods: The ethical considerations of the study were approved by the American Red Cross Institutional Review Board. Blood donations underwent a series of tests at the CDC, including pan-immunoglobulin (pan-Ig) ELISA against the full spike protein, IgG and IgM ELISAs, microneutralization tests, Ortho total Ig S1 ELISA, and receptor binding domain/Ace2 blocking activity assays​​.

Results: Of the tested samples, 106 (1.4%) were reactive by pan-Ig. Further testing of 90 available specimens showed that 84 had neutralizing activity, and others showed different levels of reactive antibodies. These reactive donations were found in all nine states, suggesting the presence of SARS-CoV-2-reactive antibodies in the U.S. prior to January 19, 2020​​.

Discussion: The detection of these antibodies indicates possible isolated SARS-CoV-2 infections in the U.S. earlier than previously known, or the presence of pre-existing antibodies that bind SARS-CoV-2. The study also notes the potential for cross-reactivity with other common coronaviruses. It highlights the importance of distinguishing SARS-CoV-2 antibodies from those of other coronaviruses for accurate serologic diagnosis​​.

Limitations and Future Directions: The study acknowledges limitations, such as the inability to definitively confirm “true positive” cases without molecular diagnostic tests and the potential for false positives. It suggests the need for further retrospective analyses to substantiate these findings. The results emphasize the utility of blood donations for SARS-CoV-2 surveillance and understanding the pandemic’s dynamics​​.

Conclusion: This research suggests that SARS-CoV-2 might have been present in the U.S. as early as December 2019, highlighting the role of blood donation screening in monitoring infectious disease outbreaks and guiding public health interventions​​.

This study offers critical insights into the early spread of COVID-19 in the U.S., underscoring the importance of diverse diagnostic approaches in pandemic surveillance.

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