September 3, 2020 -- Coronavirus antibodies may last for at least 4 months and decline at a slower rate than previously thought, according to a new study published Tuesday in the New England Journal of Medicine.
The large-scale study could indicate that a COVID-19 vaccine would be effective and help people achieve immunity, according to an editorial that accompanied the research paper.
The study “provides hope that host immunity to this unpredictable and highly contagious virus may not be fleeting and may be similar to that elicited by most other viral infections,” wrote Galit Alter and Robert Seder, two U.S. scientists who weren’t involved with the research.
In the study, scientists looked for antibodies in blood samples for more than 30,000 people in Iceland. Among the nearly 1,800 people who had recovered from coronavirus infections, 1,107 of the 1,215 people who had lab-confirmed test results had antibodies.
In addition, in a subset of 487 people who had more than one antibody test, the researchers found that antibody levels seemed to increase in the 2 months after diagnosis and remained at a plateau for the next 2 months.
Antibody levels were higher in older people and those who had more severe infections, the researchers wrote. Women also had lower antibody levels than men, and smokers had lower antibody levels than non-smokers.
Previous studies have noted that antibodies may fade in the weeks after a diagnosis and last for about 3 months. In the Iceland study, however, researchers saw that people produced a second set of antibodies about a month or so after infection, which could create longer-lasting immunity.
“Infections and vaccines generate two waves of antibodies,” Alter and Seder wrote in the commentary. “The first wave is generated by early short-lived plasma cells … but this wave subsides rapidly … the second wave is generated by a smaller number of longer-lived plasma cells that provide long-lived immunity.”
Even still, more research on coronavirus antibodies is needed, the Iceland researchers wrote. Immune responses differ widely across people, and it’s still unclear whether antibodies can prevent reinfections or long-term immunity, they said.