I Had to Take Five Antibody Tests to Get Results I Could Believe
A laboratory technician holds a blood sample in Germany. (Photographer: Krisztian Bocsi/Bloomberg)

I Had to Take Five Antibody Tests to Get Results I Could Believe

“Dear Stephanie,” the email said. “Your results are complete. The test result is: Positive.”

After my fifth test for antibodies against the novel coronavirus, the lingering doubts were finally gone: I had been infected earlier this year. It’s the only time in my life I’ve been happy to be diagnosed with a disease—albeit one I’ve already recovered from. And while I first felt a sense of liberation and a lifting of anxiety, now I have new reservations about how my new status allows me to behave.

Unlike swab tests that look for active cases of Covid-19, antibody tests have the power to look into the past, seeking telltale proteins in the blood that indicate whether a person has ever been exposed to a specific pathogen. I couldn’t get a swab test when I fell ill in February, so I was unsure if I had it. In May, I wrote about taking four different coronavirus antibody tests that used finger-prick blood samples. Two were positive and two were negative, leaving me confused. That story generated loads of email from readers anxious about their own status, with many sending me their results to ask what I thought (though I’m neither a doctor nor a scientist) and urging me to take more tests. Some were incredulous—angry even—that they’d tested negative.

My fifth test, made by global healthcare giant Abbott Laboratories, used an intravenous blood draw sent to a lab, which many believe produces a more accurate result than the finger-prick kits I’d used before. Abbott says the test is 100% sensitive to SARS-CoV-2 antibodies, meaning it won’t miss any past infection, and it’s 99.6% specific for patients if taken 14 days or more after symptoms started, so it has only a tiny chance of confusing coronavirus antibodies with those of another pathogen.

So what does it mean to be positive? I’ll be honest: It has given me some peace of mind. Antibodies against the coronavirus might protect me against another infection, though there’s no guarantee. Having gone stir-crazy working from home for the past three months, I’m even thinking about venturing back to the office one day a week.

I’m not alone. As economies reopen and employers consider ways of getting people back to work, some companies are looking at antibody testing to nudge employees off their sofas and out of endless Zoom calls. Others are using them to see if they have the right procedures in place to prevent infection.

But the tests remain an imperfect tool. Even the most reliable aren’t the “game changer” that U.K. Prime Minister Boris Johnson once proclaimed, at least not yet. Doubts remain about how long coronavirus antibodies last and how much protection they actually afford. The virus simply hasn’t been around long enough for us to have measured the duration of any natural immunity. A recent study in the U.K. reported that Covid-19 antibodies remained stable in a majority of infected people almost two months after they were diagnosed, but as many as 8.5% of patients didn’t develop antibodies at all. After the first SARS pandemic in 2002-03, researchers found that patients maintained antibodies for an average of two years, but it’s unclear if the same holds true for Covid-19.

That doesn’t mean antibody testing is useless. We need it to help us understand how long antibodies last and what role they play, says Mary Rodgers, head of Abbott’s global viral surveillance program. And knowing whether a person’s illness was in fact Covid-19 might prove valuable in diagnosing other health conditions in the future. “We’re seeing cardiovascular and lung effects, even in people who were asymptomatic,” Rodgers says. “Until we understand who’s at risk for those complications, we need to be keeping track of who actually had it.”

For me, testing positive has been a moral minefield. Initially, I felt liberated, as if the gates to a super-elite Covid-positive club had opened and I could finally go out. But when I really thought about it, I realized I still need to be a good pandemic citizen. In the U.K., you are required to wear a mask on public transport, which I rarely use these days. I normally wear a mask when I enter a store, but when I recently darted into a near-empty bookstore to quickly buy a novel for my daughter, I didn’t. I felt guilty in retrospect. Although many people in London are not wearing masks in stores, I’ve decided I will continue to do so, if only to avoid making other shoppers nervous.

While it’s not a get-out-of-jail-free card, testing positive has helped ease some fears. To celebrate, I invited two old friends over for socially distanced drinks in my back garden. They hadn’t mixed with anyone outside their house for months, and were comforted a bit by my test result. Soon after, I even went to a long-delayed dentist appointment. I remain worried about the rest of my family, who haven’t had symptoms or tested positive. But it has made the idea of going to the office occasionally look less scary.

Companies organizing antibody testing for staff aren’t treating it as a way to fill empty desks. Credit Suisse Group AG is offering a test from Swiss drug giant Roche Holding AG to employees returning to offices regularly in Switzerland and looking to roll it out to other hubs, but the bank doesn’t get to see the results. It’s more for their peace of mind, a spokesman says.

Other banks are holding off. Goldman Sachs Group Inc. hasn’t decided whether to go ahead with antibody testing, a spokesman said. In the U.K., JPMorgan Chase & Co. has so far decided against testing staff for antibodies because of the uncertainty around immunity to future infection.

The U.K. government ordered 10 million antibody tests from Abbott and Roche to test health-care workers in England after validating their accuracy, albeit in small samples. But many companies remain unsure whether antibody testing for their staff is worthwhile, given the lack of government guidance, says Jack Latus, managing director of Latus Health Ltd., an occupational health provider that’s offering Covid-19 testing to employers such as JP Morgan. Latus argues that continuous testing for antibodies is better than nothing.

“If we keep testing people to see how long they have the antibodies for, they should be safe to perform more customer-facing activities or able to work across multiple sites,” Latus says. “You can start building your business continuity plans. At the moment everyone is planning blind. If you don’t know the status of your employees, you can’t plan.”

Public health authorities in several countries are testing populations for antibodies to find out the prevalence of infection. A survey of 1,757 people in England found that 5.4% tested positive for antibodies, excluding those reported in hospitals and nursing homes. The U.S. Centers for Disease Control and Prevention said at the end of June that a national survey of blood samples showed that for every confirmed case of Covid-19, there were 10 more people with antibodies. With 2.3 million confirmed cases of Covid-19 in the U.S., that means the number of infected and asymptomatic people could be 23 million.

The reluctance of companies to check for antibodies might stem from reports that many tests were unreliable, with some regulators failing to police products being offered. In the U.S., the Food and Drug Administration allowed dozens of rapid finger-prick test kits to flood the market in mid-March without reviewing whether or not they worked. At the end of May, amid increasing reports questioning their accuracy, the FDA banned more than two dozen tests from being sold. The agency has given emergency use approval to more than 20 antibody tests, including the one made by Abbott. Independent studies of the Abbott test confirmed its accuracy.

“The finger-prick test often can’t detect low levels of antibodies, so they’re more likely to miss people,” says Alexander Edwards, an associate professor at the University of Reading who researches diagnostic testing. “You get into this gray area with people with mild symptoms. And what you want to use the antibody test for is all those people who didn’t get a swab test.”

One company that’s embraced antibody testing is Whitecroft Lighting Ltd., a commercial lighting manufacturer based in the north of England that tested more than half of its 400 employees. Many staff continued working during the lockdown, supplying lighting to some of the pop-up hospitals dedicated to Covid-19 patients, and they were eager to find out their status.

Neil McCarroll, the company’s managing director, says they debated for hours whether they should offer the tests, thinking it might even make people more anxious if they found out that someone they worked next to had antibodies from an infection they had not been aware of. Although the company had no confirmed cases of Covid-19, about 8% or 9% of about 260 who were tested came up positive for antibodies according to the Abbott test; the majority had experienced no symptoms. Everyone who took a test shared their results with the company, even though McCarroll told them testing wasn’t mandatory and they could remain anonymous.

“It’s all about the anxiety,” he says. “People wanted to talk about it. Opening their envelope was exciting. There was banter about it. There were people who were upset they didn’t have antibodies, but we’ve had a number of retests that confirmed they didn’t have it.”

McCarroll says testing has reassured management that the company has the right social distancing and sanitation procedures in place to prevent infection. While the meaning of testing positive remains unclear, the desire to find out was overwhelming. “One hundred percent of staff said they wanted to know,” he says. “I am not sure it changes anything for them, but they just want to know.”

I, too, have concluded that knowing is better than not knowing, even though I’m still following government guidelines on social distancing and working from home—waiting for scientists to figure out what it really means to test positive. And I might just get tested again in a few months.
 
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