COVID-19 Confirmed in the USA During 2019

The US National Institutes of Health (NIH) announced a new antibody testing study on June 15, 2021, found evidence of SARS-CoV-2 coronavirus infections in five U.S. states during 2019.

Of the 24,079 study participants with blood specimens tested from January 2 to March 18, 2020, seven were found seropositive before the first confirmed SARS-CoV-2 cases in Illinois, Massachusetts, Wisconsin, Pennsylvania, and Mississippi.

Antibodies are proteins produced in the blood in response to an infection, such as a coronavirus.

These antibodies do not appear until about two weeks after a person has been infected, indicating that participants with these antibodies were exposed to the SARS-CoV-2 coronavirus at least several weeks before their sample was taken.

In this study, the first positive samples came from participants on Jan. 7 and 8, 2020, respectively, suggesting that the coronavirus was present in those states in late December 2019.

In the USA, the first COVID-19 infection confirmed by the CDC was on January 19, 2020, in a traveler returning from China.

The All of Us study data is far earlier than had initially reported by the US Centers for Disease Control and Prevention (CDC).

In studies like these, false positives are a concern, mainly when the prevalence of viral infections is low, as was the case in the early days of the U.S. epidemic. Therefore, researchers in this study followed CDC guidance to use sequential testing on two separate platforms to minimize false-positive results.

“Antibody testing of blood samples helps us better understand the spread of SARS-CoV-2 in the U.S. in the early days of the U.S. epidemic when testing was restricted, and public health officials could not see that the virus had already spread outside of recognized initial points of entry,” said Keri N. Althoff, Ph.D., lead author and associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health, Baltimore, in an NIH press statement.

“This study also demonstrates the importance of using multiple serology platforms, as recommended by the CDC.”

The study authors noted several limitations to their study. While the study included samples from across the U.S., the number of samples from many states was low. In addition, the authors do not know whether the participants with positive samples became infected during travel or while in their communities.

Ideally, this study could be replicated in other populations with samples collected in the initial months of the U.S. epidemic and with multiple testing platforms to compare results. All of Us expect to release more information following further analysis.

Deidentified data from the antibody tests will be accessible to researchers for follow-up studies in a future release of the All of Us data analysis platform, the Researcher Workbench, with privacy and security safeguards in place.

The study was supported by All of Us and the National Cancer Institute. These findings were published in the journal Clinical Infectious Diseases.

Previously, a study by the American Red Cross and the U.S. CDC, entitled “Serologic testing of U.S. blood donations to identify SARS-CoV-2 reactive antibodies: December 2019-January 2020,” was published in the Clinical Infectious Diseases journal on November 30, 2020.

This study aimed to determine when the virus might have first appeared in the United States by using archived samples from routine blood donations collected by the Red Cross.

Of the 7,389 samples, 106 were reactive by pan-Ig. Of these 106 specimens, 90 were available for further testing. Eighty-four of 90 had neutralizing activity, 1 had S1 binding activity, and 1 had receptor-binding domain/ACE2 blocking activity >50%, suggesting the presence of anti–SARS-CoV-2–reactive antibodies.

The non-identifiable blood samples used in the study were from donors in nine states between Dec. 13, 2019, and Jan. 17, 2020.

The National Institutes of Health is the nation's medical research agency, includes 27 Institutes and Centers, and is a U.S. Department of Health and Human Services component. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit NIH.

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