A Massive Study Aims to Find Undetected Covid-19 Cases

It could reveal the true magnitude of the pandemic

Scientists think one reason for the rapid spread of the new coronavirus is that some people who are infected don’t get any symptoms at all. These asymptomatic carriers can unwittingly spread the virus to others.

Now, U.S. government researchers want to know just how many people might have had the virus without ever knowing it. The National Institutes of Health (NIH) announced Friday that it is launching a study to determine the extent to which the virus has spread undetected.

Researchers plan to collect blood samples from up to 10,000 people in the United States to look for clues that a person has previously encountered the virus. To do that, scientists will analyze blood samples for the presence of antibodies, or proteins that the immune system produces to fight infection. If a person has been infected, their blood will contain antibodies specific to SARS-CoV-2, the virus that causes Covid-19. A person with these antibodies could be immune to Covid-19, at least for a period of time.

“An antibody test is looking back into the immune system’s history with a rearview mirror,” said Matthew Memoli, MD, principal investigator of the study, in an April 10 statement. This is a different type of test than the one that’s being used to diagnose coronavirus cases, which involves a nasal swab and looks for the presence of the virus’s genetic material. By contrast, antibody tests are not yet widely available, though companies are racing to produce them.

Healthy volunteers over the age of 18 who have not had a confirmed case of Covid-19 or current symptoms of the disease can participate. Some participants will give a blood sample at the NIH campus in Bethesda, Maryland. Others will receive a pinprick blood collection kit in the mail to take a sample of their blood at home. They’ll then ship the sample back to investigators to be analyzed. The finger-prick test is safe and is similar to an at-home blood glucose test for diabetes.

The results of the study could provide insights into which communities and populations have been most affected by the new virus. “This study will give us a clearer picture of the true magnitude of the Covid-19 pandemic in the United States,” said Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases (NIAID) at NIH, in a statement.

A Q&A on the NIAID website says participants should not expect a rapid turnaround of their blood test results. It will take researchers weeks or months of analysis to confirm the test’s accuracy. After that, study participants can request the results of their personal test.