People infected with COVID-19 develop antibodies targeting the new coronavirus that last for at least three months, according to two reports published on Thursday in Science Immunology.
The two studies, together involving nearly 750 patients, both point to immunoglobulin G (IgG) antibodies, which start showing up well after an infection begins, as the longest-lasting.
Researchers found IgG antibodies with two targets - a spike protein on the virus that helps it infect cells, and a part of the spike called the receptor binding domain (RBD) - lasted more than 100 days.
While the protective effect of COVID-19 antibodies is not completely clear, Jen Gommerman of the University of Toronto, co-author of the study, said her team also found levels of so-called neutralizing antibodies, which inactivate the virus, "appeared to be very stable."
The other study, from Harvard Medical School, reported similar findings. This means that a properly designed vaccine "should elicit a durable antibody response that has the potential to neutralize the virus," Gommerman said.
Her group also found that antibodies in saliva correlated with antibodies in blood, but at this point the saliva tests are not sensitive enough to replace blood tests.