Despite the fact that the duration of the antibodies generated by COVID-19 patients remains unknown, there are two studies published by Science that claim that can last at least three months, after the appearance of symptoms.
The new reports agree that immunoglobulin G (IgG) are the longest-lasting antibodies detectable in the blood and saliva of patients, for at least three months, suggesting that these “may serve as promising targets for detect and evaluate immune responses against the virus “.
The fact that these antibodies can be detected at similar levels, both in blood and saliva, “suggests” that the latter could be used as an alternative biofluid for antibody testing.
The first study, led by Anita Iyer from Boston University (USA), measured the antibody responses in the blood of 343 coronavirus patients for up to 122 days after the onset of symptoms and compared it with those of 1,548 control individuals sampled before of the pandemic. The results of this indicated that IgM and IgA antibodies were “short-lived”, falling below detection levels at 49 and 71 days, respectively, after the onset of symptoms.
In contrast, the response of IgGs directed against the coronavirus Spike protein “slowly declined over a period of 90 days” and only three individuals lost them within this period.
For its part, the second study, carried out with 402 patients and led by Baweleta Isho, from the University of Canada, indicates that IgG antibodies remained “relatively stable” up to 105 days after the onset of symptoms. The data indicated that peak IgG levels occurred between 16 and 30 days after the onset of symptoms. Thus they concluded by stating that “IgG antibodies against the Spike protein of the virus are relatively durable in both blood and saliva. “