[ad_1]
(Reuters) – With most Americans under orders to stay home to help contain the spread of the new coronavirus and more than 2 million infected people worldwide, there is talk of how antibody testing could help guide efforts to lift these restrictions.
FILE PHOTO: The ultrastructural morphology exhibited by the Novel Coronavirus 2019 (2019-nCoV), which was identified as the cause of an outbreak of respiratory disease first detected in Wuhan, China, is seen in an illustration published by the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, USA. USA, January 29, 2020. To coincide with the HEALTH-CORONAVIRUS / BRITAIN-ROUTE Special Report Alissa Eckert, MS; Dan Higgins, MAM / CDC / Brochure via REUTERS. THIS IMAGE HAS BEEN SUPPLIED BY THIRD PARTIES. THIS IMAGE WAS PROCESSED BY REUTERS TO IMPROVE QUALITY, A RAW VERSION HAS BEEN PROVIDED SEPARATELY. MANDATORY CREDIT / Stock photo
What is an antibody test?
Unlike tests to diagnose disease, antibody tests show who has been infected and recovered.
The body produces antibodies in response to many diseases and infections, including other coronaviruses. New blood tests are being developed to identify antibodies unique to SARS-CoV-2, the official name of the new coronavirus.
The tests look for two types of antibodies: immunoglobulin M (IgM) and G (IgG). The body rapidly produces IgM antibodies for its initial attack on infections. It produces IgG antibodies more slowly and holds them longer; IgG antibodies suggest possible immunity.
WHAT IS THE DIFFERENCE BETWEEN TESTING AND QUICK TESTS?
Some companies are developing fingerstick tests that get results in minutes. Others are developing much more accurate tests called enzyme-linked immunosorbent assays (ELISAs) that require sending blood samples to a laboratory for analysis.
“I would argue that in current circumstances, sensitivity, specificity and precision are more important than convenience,” said Dr. James Zehnder, director of clinical pathology at Stanford Medicine in California.
WHEN ARE THE TESTS AVAILABLE?
Labs across the country are developing antibody tests that could be widely available in a matter of weeks, said Dr. Elitza Theel, director of the Mayo Clinic Laboratory for Infectious Diseases Serology in Rochester, Minnesota.
It is not yet clear how many tests will be needed, but that number could reach hundreds of millions, or when supplies will be adequate. More than 60 vendors have notified the US Food and Drug Administration. USA About plans to launch antibody tests, Theel said.
The FDA will allow the publication of some tests without a standard review if the developers determine that they are accurate. Abbott Laboratories launched a laboratory-based IgG antibody test on Wednesday without going through the FDA review and expects to send nearly a million tests this week alone.
Dozens of manufacturers are also seeking FDA approval for antibody tests under an accelerated emergency review process. Earlier this month, Cellex Inc became the first company to obtain emergency approval for an ELISA test.
BioMedomics Inc and Becton Dickinson and Co have launched a point-of-care finger prick test and said they hope to supply more than a million tests in the coming months.
As tests flood the market, accuracy will vary, Theel warned. “We have to make sure that the test we are using is giving us the most accurate results,” he said.
An ELISA test for IgG antibodies that is being developed at Mayo Clinic correctly identifies who has coronavirus antibodies more than 95% of the time, Theel said.
HOW CAN ANTIBODY TESTS HELP FINISH BLOCKS?
Antibody tests can help calculate how much of the population has already been infected, as well as whether the infections were mild or severe.
Governments and companies could use antibody tests to determine who would likely be safe to return to work and public interactions, and whether it is safe to lift orders to stay home at once in some regions or in stages based on the risk of infection.
People with negative antibody tests or very low levels of antibodies would probably have a higher risk of infection than people with high levels of antibodies.
ANTIBODIES TO THE NEW CORONAVIRUS CONFER IMMUNITY
Although antibodies against many infectious diseases generally confer a certain level of immunity, it is not yet known whether this is the case for this unique coronavirus.
And how strong immunity could be, or how long it could last in previously infected people, is unclear. With some diseases like measles, immunity can last a lifetime. With others, immunity can decrease over time.
“We cannot know for sure that reinfection is not possible until more research is done,” said Dr. David Reich, president and chief operating officer of Mount Sinai Hospital in New York City.
Lisa Rapaport’s report; edited by Nancy Lapid and Bill Berkrot
