July 23, 2020 -- People who recover from COVID-19 seem to develop antibodies that confer some type of immunity, but the antibody levels drop quickly, according to a new report from UCLA.
The research team published a short letter on Tuesday in the New England Journal of Medicine, adding their observations to the recent conversation about COVID-19 antibodies and the rapid decay in levels.
“The results call for caution regarding antibody-based ‘immunity passports,’ herd immunity, and perhaps vaccine durability, especially in light of short-lived immunity against common human coronaviruses,” they wrote.
The team studied antibody levels in 34 people who previously had COVID-19. Between ages 21-68, their average age was 43, and most had mild illness. Two people received supplemental oxygen.
The research team took two measurements — one a little over a month after the onset of symptoms and the other about three months after symptoms began. So far, researchers have reported that antibodies form within about 2 weeks of symptoms starting.
All of the participants had varying levels of antibodies, and some levels declined more rapidly than others. The average decline corresponded with a half-life of about 73 days, they wrote.
The study period was 90 days, so additional studies are needed to see the long-term effects, they added, but it’s likely that antibodies continue to decline after that.
Ultimately, antibody levels likely don’t last for a long time after a COVID-19 infection, especially for those who have a mild illness, which makes up the majority of cases. This aligns with other recent studies, they wrote.
At the same time, a decline in antibodies doesn’t necessarily mean that protection disappears entirely or that a vaccine won’t be effective. Certain immune system cells store information about viruses to create new antibodies if needed, according to The Associated Press.
“This shouldn’t dissuade us from pursuing a vaccine,” Buddy Creech, an infectious disease specialist at Vanderbilt University, told the news outlet. “Antibodies are only a part of the story.”