JdeM asked recently: “We know that COVID-19 is a flu-like viral infection. Or is it? I was wondering how long anti-bodies stay in the body after getting the (regular) flu or a cold?”
Great question! We know that COVID-19 is caused by a new coronavirus, which is a family of RNA viruses (meaning their genetic material is composed of ribonucleic acids) that can cause diseases in mammals and birds. In humans, these viruses cause respiratory tract infections that can range from mild to lethal. Mild illnesses include some cases of the common cold (which is also caused by other viruses, predominantly rhinoviruses), while more lethal varieties can cause SARS, MERS, and COVID-19. It is not an influenza virus, but it does cause respiratory illnesses.
And we do know that people who have been exposed to COVID-19 develop antibodies against the virus. A previous post covers how vaccines and antibodies work, but antibodies, are large, Y-shaped proteins produced mainly by plasma cells that is used by your body’s immune system to fight off infections.
However, we do not know much about the long-term effects of this virus and how long the antibodies remain in the body.
But, as JdeM asked – what is normal for diseases like flu?
Again – it is hard to extrapolate – since some vaccines for diseases can confer immunity for decades and some for much shorter times (like months).
An interesting Time Magazine article from years ago quoted a study that found that some people tested were still producing antibodies to the 1918 Flu many years after they had been exposed. It’s only many virus’s pesky tendency to constantly change (and become different variants) that renders these antibodies ineffective.
However – not all viruses cause this wonderful happenstance.
Antibodies are made by something called memory B cells, and while the memory B cells of say the 1918 flu can live for someone’s lifetime, not all viruses and memory B cells are created equal.
Some early research on COVID-19 is not quite as encouraging. One study of 1,500 COVID-positive people found that 10 percent registered undetectable antibody levels within weeks after they of first showed symptoms. Another smaller study found patients typically lost their antibodies two to three months after recovering from the infection, especially among those who tested positive but had no symptoms.
However – much research still needs to be done, so stay tuned!