Reader may have had mild COVID-19

Dear Dr. Roach: I’ve had regular swab tests for COVID-19, which have always been negative. The last one was just a few days ago. I had an antibody test six weeks ago that also was negative, but my antibody test this time was strongly positive. I haven’t had any symptoms! I’m scheduled to get my first dose of vaccine tomorrow. What should I do?

Answer:

C.W.

With frequent negative swab tests and no symptoms, your likelihood of having had COVID-19 is lower than the average person in your community. But if your community has been hit hard, as most have, there is a good chance that you recently had an asymptomatic infection.

The antibody test result you sent showed a strongly positive result using a very highly specific laboratory assay. Although it is possible this is a false positive test result, I suspect you had a true COVID-19 case so mild that you noticed no symptoms.

You probably have some immunity against another case of COVID-19, but that immunity may wear off quickly. I recommend you get your vaccine as scheduled. It is safe to get the vaccine as long as you have no symptoms.

Dear Dr. Roach: I know someone who had the first and now second dose of the Moderna vaccine and did not get any of the side effects from either one of them. Does it mean the vaccine is not working? Everyone talks about the side effects, but no one mentions if you do not have side effects. Please clarify.

M.J.

Answer: I often hear doctors and patients explain vaccine reactions, such as sore arm and fever, as evidence that “the vaccine is working.” It’s natural to worry that no reaction means the vaccine isn’t working. However, that’s not the case. Even people with no side effects whatsoever get benefit from the vaccine.

It is true that people who have a history of COVID-19 infection are more likely to get a side effect like fever or fatigue. So, I wouldn’t say that the person you know who had no side effects had necessarily a “strong” immune system. But it does mean they are less likely to have had COVID-19 in the past.