While the world waits for a vaccine against SARS-CoV-2, the novel
coronavirus that causes COVID-19, one likely control and exit strategy
is testing for immunity, or an antibody test. This is different than the
testing for the virus that determines if you have the disease. Antibody
tests identify if you have developed antibodies against the virus,
suggesting that you should have immunity against the disease, having
been previously exposed.
On April 3, the U.S. Food and Drug Administration (FDA)
approved the
first blood test for antibodies against COVID-19. That was by Research
Triangle Park, North Carolina-based Cellex. About the same time, Mayo
Clinic developed its own antibody test and began offering it on April 6.
Stanford Medicine researchers have
joined the list
of organizations that have developed an antibody test, which was
launched April 6 at Stanford Health Care. It is different from an
externally developed test Stanford utilized for a prevalence study
during a community screening event.
The Stanford test provides results in two to three days and Stanford
Health Care can test 500 samples per day. It believes it can scale that
up quickly.
“It’s essential to have the right tools to understand the biology of
the novel coronavirus,” said Lloyd Minor, dean of the Stanford
University School of Medicine. “This test takes us one step closer to
answering the many public health questions about COVID-19.”
Although commercial antibody tests—also called serological tests—are
being developed globally, Thomas Montine, professor and chair of
pathology at the Stanford School of Medicine, says their quality is
variable. “We thought this was an urgent medical need, and the usual
supply chains were unreliable, so we decided to build our own.” He
added, “Serological testing gives us a more comprehensive view of what’s
happening in an individual who is infected, or has been infected, with
the virus.”
Elitza Theel, director of the Mayo Clinic laboratory that offers
COVID-19 antibody tests, told Minnesota Public Radio (MPR), “It’s
important to know that these types of tests are different than all of
the molecular tests that are being done off of nasal swabs or throat
swabs. Those tests detect viral genetic material [to show whether the
coronavirus has infected that person].”
In some cases, it can take 10 to 11 days for an individual’s immune
system to attack the virus and produce the antibodies. This is why the
antibody tests aren’t used to diagnose patients with COVID-19 that have
shown symptoms within the last two or three days.
The Stanford test identifies two different types of antibodies, IgM,
which show up early in the immune response but whose levels quickly
drop, and IgG antibodies, which increases more slowly after an
infection, but generally stick around longer.
“There’s limited data out of China and Europe showing that this
appears to be the response pattern followed with this virus,” Montine
said. “But no one has had this long enough to know how long after
infection the antibodies persist.”
The Stanford test will have two findings: positive or negative for
IgM antibodies, and positive or negative for IgG antibodies. The team
began work on the test on March 22, focusing on ensuring the ability to
manufacture large amounts of the reagents necessary, especially the
receptor binding domain of the SARS-CoV-2 spike protein. They have
validated the test with samples from patients who tested positive on the
diagnostic tests as well as on plasma samples that were collected more
than two years ago, which would guarantee they were negative for the
virus.
They are now focusing on scaling up and determining who will be the
first to receive the antibody test. The top priority will likely be
health care staffers and other people in the hospital setting.
“We’ve built sufficient inventory to support the test for at least
six months,” Montine said. “We’re currently limited by the number of
robots we have to run the test. We’re looking for more of them, but
they’re not easy to buy right now. Ultimately, we aspire to provide
serological testing to as many people in Northern California as we can.”
They are applying to the FDA for emergency use authorization.
https://www.biospace.com/article/stanford-develops-covid-19-antibody-test/
