The U.S. Centers for Disease Prevention and Control (CDC) has provided guidance on a new serology test it developed for SARS-CoV-2, the virus that causes COVID-19, and on its community surveillance approach to deployment of measures of immune response.
The CDC's SARS-CoV-2 test is developed for "broad-based surveillance and research" that the agency hopes will help guide its response to the COVID-19 pandemic and protect public health, as opposed to testing of individuals who want to know if they were previously infected, it said.
"The results of these studies will allow us to estimate how many people have been infected nationally ... and will provide information about the percentage of U.S. residents who have not had COVID-19 and are still at risk for infection," the CDC said. "This research is designed to help us understand who has been infected with SARS-CoV-2 and determine factors that confer protection against this virus."
Serology tests are used to identify antibodies, proteins the body creates in response to infection. The CDC's test determines if a person has had an immune response to SARS-CoV-2, whether he or she was symptomatic or not. Serology tests are especially helpful with illnesses that don't necessarily manifest symptoms, the center said.
Development of the CDC test began in late March with samples taken from Washington state and New York City. The second stage of its development will include serologic testing in more areas across the country and higher numbers of people who were diagnosed with COVID-19.
The center is also exploring the commercial manufacture of serological tests in collaboration with the following:
- The U.S. Biomedical Research and Development Authority
- The U.S. Food and Drug Administration
- The U.S. National Institutes of Health
- The U.S. Department of Defense
- The White House Office of Science and Technology Policy
Serology testing for COVID-19 antibodies must be conducted correctly, the CDC said.
"It typically takes one to two weeks after someone becomes sick with COVID-19 for their body to make antibodies; some people may take longer," the CDC said. "Depending on when someone was infected and the timing of the test, the test may not find antibodies in someone with a current COVID-19 infection."