Just say ‘no’ to antibody testing

As a doctor in New York City, it has become my job, both in the hospital and with my family and friends, to answer questions about the coronavirus. Today’s hot topic is antibody testing, and I’ve been asked daily where people can get this new diagnostic breakthrough. However, my response is as disappointing as it is urgent: completely avoid current antibody testing. Our scattered and unscientific approach to antibody detection is worse than useless, and individual tests threaten to do real harm.

During this pandemic, rapidly changing and seemingly conflicting recommendations have left us in a state of scientific whiplash. With so many private doctors, hospitals, and labs hastily promoting individual testing, we must step back and decide if this really is the best course of action. Each advance in coronavirus diagnosis and treatment brings us to a crossroads, a tipping point where we have the opportunity to proceed quickly as individuals or to create a collective approach carefully. Now that FDA-approved tests are finally on our doorstep, it’s time to slow down. The truth is, individual testing doesn’t get us anywhere, and rushing into a disorganized, private test for all will only slow us down in the fight against this devastating pandemic.

Even something as simple as “precision” depends on our ability to carefully test and analyze the results. The best tests on the market, now “over 99 percent accurate,” use laboratory calculations called “specificity” and “sensitivity” to support these claims. But these numbers are just the beginning of calculating what false negative and false positive rates look like in the real world. False negatives are more likely in an area where a disease is very common, due to the simple probability.

On the contrary, it is much more difficult to trust a positive result in an area where the disease you are looking for is quite rare. And there are more chances that they come into play. A negative result is more likely to be false than real if our suspicion of a disease is already very high, whereas we should be careful with any positive test result in a patient whose presentation makes the diagnosis of the disease extremely unlikely. Even a pregnancy test that is “99.9 percent accurate” will be positive for 1 in 1,000 biological men who take it. Without a careful and critical eye, even the most “accurate” test results are meaningless.

Many, including doctors, find that a potentially incorrect test result is better than nothing. But the isolated results are not only unreliable, they are also impossible to interpret clinically. We do not yet know what levels of antibodies are protective or how long this protection lasts. We also know from other viruses that even people without detectable antibodies can have some protection against the disease if they were exposed to the disease. For now, even “correct” antibody tests do not translate into immunity. For many, the negative results will only cause unnecessary increases in anxiety. And for others, positive results of unclear significance will give a false sense of security, amplify the cabin fever and undermine the return to systematic, regulated and sensitive work and the reopening of society.

Most importantly, random testing without a clear strategy detracts from the organized testing efforts we need to move forward. We have seen how important consistent testing strategies are in other countries. In Germany and South Korea, organized testing that reported contact tracing, isolation, and high-level policies was a crucial part of a response that led to early containment of the coronavirus and enviable low death rates. Generalized testing and speed of action are key to a successful public health policy. But this only matters if the data can be collected, organized and translated into compelling science policy. With the antibody test, which is much more difficult to interpret than nasal PCR results, critical interpretation of a large data set is the key to making this information meaningful.

The lessons of the pandemic are difficult to learn and full of endless loss. “Accurate” antibody testing presents us all with an opportunity to learn from our mistakes. Let’s pause and ask our leaders to sit down with the scientists and create a smart and thoughtful action plan together. Acting strategically is as important as reacting quickly. For now, we should all say “no” to individual antibody testing and demand a clear testing plan for this progress to translate into real progress. It will take us longer to see our own antibody levels, but the results we get will make sense.

Rebekah Diamond MD is an assistant professor at Columbia University Medical Center and a pediatrician at the NewYork-Presbyterian Hospital. The views expressed here are entirely yours and do not necessarily reflect those of your affiliated institutions.