Why Are Our Bodies Forgetting How to Fight COVID-19?

The race for a COVID-19 vaccine has been well underway with companies racing to release a vaccine by the fall. But what happens when scientists finally have one? Is that the end of our worries or should we still tread with caution? Reports of recovered patients falling ill a second time within days of recovery, seems to point to the latter. 

The NHK-World Japan reported that on March 14 a man who had previously recovered from COVID-19 was tested positive once again. This can mean a couple of things.:

#1 The man was thought to be fully recovered with disappearance of symptoms and a negative COVID-19 test, but was still carrying a very small amount of the virus in his body. This went undetected by the test and he simply later had a flare up.

OR

#2 He was reinfected with the virus for a second time.

What’s worrying about the second scenario is why a recovered patient would not be able to fight off the virus a second time if his body already has ready- to-deploy defenses, in the form of antibodies, against the virus?

It turns out, the antibodies made while fighting the virus the first time may not last very long in the body of recovered individuals. The South China Morning Post reported that researchers from Fudan University analysed blood samples from patients that had been discharged from the hospital, only to find that about a third of them had surprisingly low levels of the antibodies. Some samples had levels that were below detectable.

So what does this mean in terms of vaccines? The whole point of a vaccine is to provide our bodies with a small part of a virus, harmless in comparison to the real thing, so that our immune cells can encounter it and make specific neutralizing antibodies against the virus. If exposed to the real thing, our bodies are immune, nothing to worry about. But if recovered patients, people who made these antibodies after contracting the real virus and successfully fought it off, are getting sick a second time and barely have detectable antibodies after recovery, then how long will a vaccine really help?

Our immunologic memory after exposure to the virus is something that needs more investigating. The hope is researchers find a vaccine that elicits a more long term response in the immune cells that produce the virus fighting antibodies.