Antibody testing for COVID-19: Here’s what you need to know

Although we’re still in the thick of the COVID-19 pandemic — more than 3 million cases have been reported worldwide, nearly one-third of which are in the US — the good news is that more than 110,000 people in the US have recovered from it, according to research from Johns Hopkins University.

That’s a lot of folks with the potential to donate antibody-rich blood plasma to those still suffering from the virus, a promising treatment to boost immunity.

But what if you don’t even know if you had coronavirus? How do you find out if you have antibodies? And how do you donate plasma?

There’s a lot of buzz about antibody testing and whether or not having antibodies means you’re immune to the coronavirus. Experts, including Dr. Anthony Fauci, have cautioned against reliance on antibody tests, but many are hopeful.

Here’s what you need to know about antibody testing and plasma donation:

What is an antibody test?

Antibody or “serology” tests don’t diagnose an illness, they scan for proteins called antibodies that form in response to a virus. When found in blood, it means that person was exposed to a particular virus, with varying degrees, and has formed some level of immunity to that illness.

If I had COVID-19 and recovered, am I now immune?

Probably, but even with an antibody test, it’s still unclear.

“We are reluctant to say that a positive antibody test means you are immune,” says Dwayne Breining, MD, a pathologist at Northwell Health. “[But] with our past experience with other coronaviruses like SARS and MERS, and through emerging info with this one, when someone has an infection and they have recovered, then generally you will have temporary or seasonal immunity.”

Breining pins this uncertainty on COVID-19 being a brand-new virus, which means the tests are brand-new as well, “so we have less of a degree of certainty [of immunity] … until we do large-scale testing and follow-through with that testing,” but, he says, “it is reasonable to expect a similar immunological response with this virus.”

Fauci agrees and warns that research has not yet proven immunity for this novel coronavirus. “There’s an assumption — a reasonable assumption — that when you have an antibody that you are protected against reinfection, but that has not been proven for this particular virus. It’s true for other viruses,” he said on “Good Morning America” earlier this month.

While it’s true that antibodies remain in the body for life, the problem is that some viruses evolve or get smarter, and “they trick your immune system” to not recognize them again, Breining says.

“From what we know about the coronaviruses, they change their coats,” Breining says, adding that a good example is the flu, for which we need a new shot every year.

If I tested positive for antibodies or had a positive COVID-19 test and am now symptom-free, do I need to wear a mask and practice social distancing?

Yes. You should still practice all standards as advised by the Centers for Disease Control and Prevention, including wearing a mask and washing your hands frequently.

“If [someone] had a documented infection that they have then recovered from then it is likely that they are safer than someone who has not had it to [go out for errands], but only if [they] still follow reasonable precautions,” Breining says. “There is a risk they could still transmit the disease even if they have recovered. Based on the available evidence, it can survive on clothing, so if you brush up against something or grab an item someone else has coughed on, you just don’t know.”

Do I need to have had a positive COVID-19 test to get an antibody test?

No. But if you never tested positive for COVID-19, you won’t be a candidate for donating plasma without a positive antibody test.

Conversely, if you already have documentation of a positive COVID-19 test, then in most cases, you don’t need an antibody test to donate plasma, Breining says. Contact your blood bank or the hospital directly. At Northwell Health, for example, recovered COVID-19 patients who are symptom-free can register to donate their plasma at, they will then be directed to a New York Blood Center.

How can I get an antibody test and what does it entail?

In New York, you need a prescription for most lab work, but you can call or telecall your doctor and ask for a test. You can also go to a walk-in clinic and ask for the test, and they will determine your candidacy. Breining says that currently, at his lab, they are prioritizing health-care workers and first responders for antibody tests. New York state is prioritizing those groups as well; Gov. Andrew Cuomo announced that the NYPD will test 1,000 officers for antibodies this week.

The tests themselves also vary, some are finger pricks (such as the forthcoming at-home tests), and some require blood drawn from the arm.

Is it covered by insurance?

Insurance providers vary, but in most cases, the antibody test would fall under your blood work and lab testing policy.

Are the home antibody tests reliable?

Labs across the world are racing to create the most accurate testing possible. But that rush can lead to errors.

“The problem is that these are tests that need to be validated and calibrated, and many of the tests out there don’t do that,” Fauci said last week. “So even though you hear about companies flooding the market with these antibody tests, a lot of them are not validated.”

How does convalescent plasma work?

“Blood transfusions have been used to treat infectious disease for well over a century,” Breining says. “The idea is the antibodies in the donor’s blood, when given to a patient that is sick with that same infection, can help that patient recover. The presence of the antibodies seems to stimulate the immune system in some way.”

In a new study out of China, one dose of convalescent plasma was effective to help treat COVID-19, but only 10 people were studied.

“Convalescent plasma use is still predominantly used in other countries that don’t have access to expensive drugs like we do. It’s been successful,” Breining says.

What else can antibody testing teach us about COVID-19?

“As we do more antibody testing, we are discovering that far more people had this infection than anyone knew about,” Breining says.

“We probably are not testing one-tenth of the people we should have when this thing started, however, the silver lining in that could mean that the virus is not as deadly as everyone feared,” he says. “If there are 10 times as many infections, then that means there’s one-tenth less death.”

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