How long do COVID-19 antibodies last? That seems to be the question on everyone’s mind for the majority of 2020. However, the answer seems to change quite frequently.
The research that produced these conclusions, conducted by scientists at the University of Toronto and the Lunenfeld-Tanenbaum Research Institute (LTRI) at Sinai Health, was made possible thanks to blood and saliva samples collected from dozens of COVID-19 patients. Those samples were used to compare antibody levels across patients over the course of three months after symptoms first appeared.
More specifically, IgG antibodies were detected in recovered patients’ samples for at least 115 days post-symptom onset. Those antibodies are quite important when it comes to fighting off future potential coronavirus infections; they bind to and subsequently neutralize the SARS-CoV-2 spike protein (which is used by the coronavirus to infect new cells).
Notably, this is also the first study to successfully detect coronavirus lgG antibodies in patient saliva samples.
“Our study shows that IgG antibodies against the spike protein of the virus are relatively durable in both blood and saliva,” says study leader Jennifer Gommerman, professor of immunology at the University of Toronto, in a release. “Our study suggests saliva may serve as an alternative for antibody testing. While saliva is not as sensitive as serum, it is easy to collect.”
Virtually everyone who recovers from a COVID-19 infection will show some antibodies in their body. Besides just providing a certain measure of protection against re-infection, keeping track of antibodies across population samples can also reveal who had been infected with the coronavirus – regardless of whether or not the infection is currently active. In this sense, antibody testing represents a superior option to straight-up COVID-19 infection tests that only identify active cases.
The saliva research was handled by the University of Toronto researchers, while scientists at LTRI took care of the blood tests.
“The LTRI platform for detection of antibodies in serum, or blood, is incredibly robust and well suited for assessing the prevalence of infection within the community,” notes senior investigator Anne-Claude Gingras, a professor of molecular genetics at the University of Toronto. “This is another tool that can help us better understand and even overcome this virus.”
Scientists have been debating for months just how long coronavirus antibodies stay in the body, especially for individuals who were asymptomatic in the first place. Some studies suggest antibodies disappear as quickly as two months later, but these latest findings out of Canada agree with the leading American immunologists.
So, while it’s impossible to say with absolute certainty at this point, it’s looking more and more like COVID-19 antibodies remain in blood and saliva for at least three months. Similarly, the jury is still very much out regarding just how much protection these antibodies actually provide against potential coronavirus re-infection.
All that being said, this study is certainly a step in the right direction for the medical community’s overall understanding of COVID-19 and its long-term effects on the human body. On another positive note, these conclusions bode well for a future vaccine.
“This study suggests that if a vaccine is properly designed, it has the potential to induce a durable antibody response that can help protect the vaccinated person against the virus that causes COVID-19,” professor Gommerman concludes.
The full study can be found here, published in Science Immunology.