The world has been sheltering in place for over a month now and everyone wants it to end. There is much speculation about when cities in the US could start functioning again. I've had a number of patients and friends ask about antibody tests to see if one has actually had Covid. Most everyone can remember a "cold" or "sore throat" that they had since December and now wonder "Did I really have Covid-19?"
The answer to that will be provided with a serologic (blood) antibody test. By taking a few drops of blood (not nasal swabs) we will be able to see if a person has built up antibodies to the virus. That would mean they were at one time infected. We still don't know what level of antibody provides protection against catching it again, but if Covid-19 follows other viruses, it should be one-and-done, at least for a couple of years, which gives us time to develop a vaccine.
A number of studies are ongoing in humans to answer the question of who has antibodies, how long they last and how protective they are. Here is what an antibody test can tell us if we could test a majority of our population:
- The true infection rate and when 60% of the population has been infected we would have "herd immunity" and a very low incidence going forward.
- The true mortally rate. Up until now we have been guessing. If it is much less than regular influenza we can get back to work.
- Who has antibody and is safe to work and travel
- Protection of health workers by showing who is at low risk to care for Covid-19 patients.
- Information about the virus and how it spreads and how contagious it is.