NIH Begins Study to Quantify Undetected Cases of Coronavirus Infection

Blood Samples from Healthy Volunteers Needed to Inform Public Health Decision Making

April 10, 2020

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A woman in a white lab coat (Kaitlyn Sadtler, Ph.D., study lead and principal investigator for laboratory testing) uses her gloved hand to hold up a small white microsampling device from the home blood collection kit used in the study.

Kaitlyn Sadtler, Ph.D., study lead for laboratory testing, holds up a microsampling device from the home blood collection kit used in the study.

Credit: NIBIB

A new study has begun recruiting at the National Institutes of Health in Bethesda, Maryland to determine how many adults in the United States without a confirmed history of infection with SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), have antibodies to the virus. The presence of antibodies in the blood indicates a prior infection. In this “serosurvey,” researchers will collect and analyze blood samples from as many as 10,000 volunteers to provide critical data for epidemiological models. The results will help illuminate the extent to which the novel coronavirus has spread undetected in the United States and provide insights into which communities and populations are most affected.

The study will be conducted by researchers at the National Institute of Allergy and Infectious Diseases (NIAID) and the National Institute of Biomedical Imaging and Bioengineering (NIBIB), with additional support from the National Center for Advancing Translational Sciences (NCATS) and the National Cancer Institute (NCI), all parts of NIH. 

“This study will give us a clearer picture of the true magnitude of the COVID-19 pandemic in the United States by telling us how many people in different communities have been infected without knowing it, because they had a very mild, undocumented illness or did not access testing while they were sick,” said Anthony S. Fauci, M.D., NIAID director. “These crucial data will help us measure the impact of our public health efforts now and guide our COVID-19 response moving forward.”

Investigators will test participants’ blood samples for the presence of SARS-CoV-2 antibodies, proteins the immune system produces to fight a specific infectious agent. A positive test result indicates previous infection. To date, reporting of U.S. cases of COVID-19 has mostly relied on molecular tests that determine the presence of the virus in a person’s airways using a noninvasive cotton swab. While these cotton swab-based tests rapidly and effectively identify active infection, they do not determine whether a person was previously infected with SARS-CoV-2 and recovered. 

“An antibody test is looking back into the immune system’s history with a rearview mirror,” said Matthew J. Memoli, M.D., M.S., principal investigator of the study and director of NIAID’s Laboratory of Infectious Diseases Clinical Studies Unit. “By analyzing an individual’s blood, we can determine if that person has encountered SARS-CoV-2 previously.”

Investigators will analyze blood samples for two types of antibodies, anti-SARS-CoV-2 S protein IgG and IgM, using an ELISA (enzyme-linked immunosorbent assay) developed by researchers at NIAID and NIBIB. In blood samples found to contain antibodies against SARS-CoV-2, researchers may perform additional tests to evaluate the volunteers’ immune responses to the virus. These data may provide insight as to why these cases were less severe than those that lead to hospitalization.

Healthy volunteers over the age of 18 from anywhere in the United States can participate and will be asked to consent to enrollment over the telephone. Individuals with a confirmed history of COVID-19 or current symptoms consistent with COVID-19 are not eligible to participate. 

After enrollment, study participants will attend a virtual clinic visit, complete a health assessment questionnaire and provide basic demographic information—including race, ethnicity, sex, age and occupation—before submitting samples in one of two ways. Participants working at the NIH Bethesda campus will have blood drawn at the NIH Clinical Center. Other volunteers will participate in at-home blood sampling. Neoteryx, a medical device firm based in Torrance, California, will supply at-home blood collection kits. Researchers will ship each study participant a Mitra® Home Blood Collection Kit and provide detailed instructions on collecting a microsample of blood and mailing it back for future analysis in the laboratory.

“Researchers have considerable experience using these at-home blood collection kits to track the spread of other infectious diseases like influenza, and this method is safe, effective and easy-to-use,” said Kaitlyn Sadtler, Ph.D., study lead for laboratory testing and chief of NIBIB’s Section for Immunoengineering. “With a small finger-pick, volunteers can help scientists fight COVID-19 from their homes.”

People interested in joining this study should contact For more information on this study, please see the Questions and Answers below, and visit using identifier NCT04334954. For more information on the U.S. government response to the COVID-19 pandemic, visit


To schedule interviews, contact:
NIAID Office of Communications (Media only)
(301) 402-1663

Questions & Answers

COVID-19 Pandemic Serum Sampling Study Launch

The study is being funded and conducted by the National Institute of Allergy and Infectious Diseases (NIAID) and the National Institute of Biomedical Imaging and Bioengineering (NIBIB) with additional support from the National Center for Advancing Translational Sciences (NCATS) and the National Cancer Institute (NCI), all parts of the U.S. National Institutes of Health. The study will be led by principal investigator Matthew J. Memoli, M.D., M.S., director of NIAID’s Laboratory of Infectious Diseases Clinical Studies Unit.

Study volunteers will be screened, consented and enrolled over the phone by investigators at the NIH Clinical Center in Bethesda, Maryland. Most volunteers based outside of the Washington, D.C. metropolitan area will participate in virtual clinic visits and at-home blood collection. Local volunteers will be seen and have blood drawn during a visit to the NIH Clinical Center.

To participate, volunteers must be over the age of 18 and living in the United States. Volunteers must be willing to complete a verbal telephone consent, undergo one blood draw or at-home blood collection and have blood samples stored for future research.

People with laboratory-confirmed history of COVID-19 or current symptoms consistent with COVID-19 are not be eligible for the study. Individuals who suspect they have recovered from COVID-19, but never accessed laboratory testing while ill are eligible. People who have never had symptoms consistent with COVID-19 also are eligible to participate.

Volunteers may enroll in the study up to four times no fewer than 30 days after previous enrollment.

This study is a natural history study, meaning data are collected over time to better understand how a disease progresses. In this case, investigators are collecting blood samples from volunteers to determine how COVID-19 spreads through a population. No medical intervention is being tested to prevent or treat COVID-19 in this study.

Investigators will enroll and consent participants by phone. After phone consent is provided, a virtual clinic visit will be performed to obtain pertinent health information. All participants will complete a COVID-19 screening questionnaire.  If found to be at risk of COVID-19 because they are currently experiencing symptoms or are in close contact with a person with COVID-19, participants will be instructed to contact their medical provider. Those not at risk will be referred to the NIH Clinical Center phlebotomy lab for a blood draw or instructed on how to participate in home sampling.

In-person sampling at the Clinical Center will consist of a blood draw to collect two 18-milliliter tubes of blood. In-home, self-sampling will be performed using the Mitra® Home Blood Collection Kit developed by Neoteryx. This kit contains a microsampling device, gauze, a finger-prick lancet and all necessary shipping materials, as well as detailed instructions for participants to collect their own 80-microliter sample of blood. Volunteers using these kits will then mail the sample back to investigators as directed for later testing in the laboratory.

Yes. Investigators will provide volunteers with detailed instructions to collect and submit a microsample of blood using the Mitra® Home Blood Collection Kit developed by Neoteryx, which is registered with the U.S. Food and Drug Administration (FDA) as a Class 1 Medical Device. Like a blood draw at a doctor’s office, risks of at-home blood sampling include discomfort, bruising and, rarely, fainting or infection at the site where the lancet enters the skin. The kit includes bandages and gauze to reduce the risk of infection.

It also is safe to ship these kits in the mail. The blood samples are dried and contained in a sealed, tamper-proof pouch. Regardless of the infection status of the volunteer, there is no risk of bloodborne SARS-CoV-2 transmission to the mail carrier or others who handle the package.

Results will be reported to federal public health authorities on a rolling basis to support epidemiological modeling efforts and inform public health decision making. When results are reported, they will be released as a data summary noting basic demographic information. The identities of the volunteers will remain private.

Volunteers should not expect a rapid turnaround of their blood test results, as investigators will provide this information only after weeks or months of analysis to confirm the test’s accuracy. After this period, volunteers may be provided with their personal test results upon request to the study team.

Researchers have not yet confirmed whether the presence of SARS-CoV-2 antibodies in a person’s blood means they are fully protected from COVID-19. Based on what is known about similar viruses, this protection is likely; however, more research is needed. In fact, that is one research question this study may help answer.

All people in the United States should adhere to public health guidelines as outlined by the CDC and local authorities. A person’s behavior should not change based on antibody test results from this study.

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