Dear Dr. Eva,

I was sick for 3 weeks. It seemed like COVID. I had a bad cough, was short of breath, was totally exhausted and my sense of taste and smell were less than normal (but didn’t disappear completely). I had five COVID tests and they all came up negative. My doctor says she thinks I probably did have COVID. Is it possible to have COVID and keep testing negative for it?

Been Pretty Sick


Dear BPS,

Testing for COVID is very finicky and time-sensitive. There are three main kinds of COVID tests: antigen tests, DNA tests, and antibody tests.

DNA tests and antigen(Ag) tests are both used to check for current COVID infection. Both DNA and antigen tests turn positive, showing the presence of COVID, after a person has been infected for about five days. The tests can turn negative as soon as five days later. So if a person with COVID doesn’t get tested in the five day window between the fifth and tenth day after they are infected, they may never have a positive test.

Antibodies (Ab) in the bloodstream are a sign that a person previously had an infection. Our bodies make disease-specific antibodies for every type of infection. Unfortunately, tests for COVID antibody are are only 50% accurate, meaning the results may be no better than flipping a coin. Although these tests are sometimes ordered, the results often are not useful because their accuracy depends on how common the disease is within that geographic area at the time, as well the limitations of the test itself. Better antibody tests are being developed but aren’t available yet. Generally, positive tests of all types are more reliable than negative ones. That means that if any of the COVID tests is positive, that is a strong suggestion the person now has or previously had COVID. However, if the test is negative, it doesn’t accurately tell if the person has (or had) COVID or not.

So you can see that yes, it is very possible to have COVID without having a positive test. Some people have died of COVID after having as many as a dozen negative COVID blood tests; tests done on their internal organs after death finally showed the virus.

In the situation of a pandemic, when many people are becoming infected with a disease that is difficult to test for, it is very reasonable to make the diagnosis of COVID without a positive test. This is especially true when a person has symptoms that are unusual and are typical of COVID. In your case, the decrease in your sense of taste and smell are a strong indication that you did have COVID.     

Dr. Eva

Dear Dr. Eva,

Is there really any such thing as long COVID, or is it just the trauma of getting back into the world and back to work? I know lots of people who haven’t had COVID and are still having trouble re-entering the work world.


Dear Skeptic,

You make an interesting point. It’s true that, just like getting used to isolation was difficult and took time, the readjustment to “normal” life has turned out to be difficult for many people. Still, readjustment stress is not the same as being sick.

Ongoing sickness after COVID infection is more than a readjustment problem. For a small number of people, COVID causes permanent damage to their lungs, heart, kidneys or brain. Many more people, more than one-third of everyone who has COVID, develop long COVID. Long COVID means having symptoms that start during or following COVID infection and continue for months after the initial illness is over. In addition to “long COVID”, this condition is sometimes called “post-COVID-19 syndrome.”  People who have long COVID are sometimes called “post-COVID long haulers.”

Because this is a new condition, there isn’t yet a standard definition of how many months the condition has to continue to be considered a case of long COVID.  Different studies on long COVID have surveyed people from as little as two months after their initial illness to as much as one year afterwards. The commonest long-term symptoms are fatigue (71% in the largest study), cough (61%), and headache (61%). ‘Brain fog,’ difficulty with memory and concentration, is also common. People with long COVID also may have body aches, shortness of breath, weakness with inability to exercise, and difficulty sleeping. Early studies show that one in ten people with COVID-19 develop long COVID that lasts a year or longer.

At first it was thought that long COVID only happened to people who were sick enough with COVID to be hospitalized. It is now known that people who were only mildly ill with COVID develop long COVID as often as people who were hospitalized. Long COVID happens more often to people over age 50 and people with two or more chronic illnesses, but it also happens to young people who had no health problems before COVID.

There is no specific test for long COVID. It is a clinical diagnosis, which means that the diagnosis is made based on the patient’s history and physical exam.

Dr. Eva

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Dr. Eva Hersh, MD
Dr. Eva Hersh, MD
Eva Hersh is a family physician. Send your comments and questions to her by email at