99 percent of those with confirmed infection had anti-RBD antibodies versus 55 percent of those with unconfirmed infection<\/p>\n<\/h3>\n
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MONDAY, Feb. 7, 2022 (HealthDay News) — Anti-receptor binding domain (RBD) antibodies are detected in 99 percent of unvaccinated individuals who reported confirmed COVID-19 infection up to 20 months after infection, according to a research letter published online Feb. 3 in the Journal of the American Medical Association<\/em>.<\/p>\n Jennifer L. Alejo, M.D., from the Johns Hopkins University School of Medicine in Baltimore, and colleagues recruited healthy adults who reported no severe acute respiratory syndrome coronavirus 2 vaccination. Three equally sized sample groups were created: those who reported a test-confirmed COVID-19 infection, those who believed they had COVID-19 but were never tested, and those who did not believe they ever had COVID-19 and never tested positive (COVID-19-confirmed [295 participants], COVID-19-unconfirmed [275 participants], and no-COVID-19 [246 participants]). The groups underwent antibody testing.<\/p>\n The researchers found that 99 percent of the COVID-19-confirmed participants tested positive for anti-RBD antibodies. The median anti-RBD level was 205 U\/mL at a median 8.7 months (range, 0 to 20 months) since reported COVD-19 diagnosis. No evidence of an association was seen between time after infection and antibody titer. Fifty-five percent of the COVID-19-unconfirmed group tested positive for anti-RBD antibodies, with a median level of 131 U\/mL. Eleven percent of the reported no-COVID-19 participants tested positive for anti-RBD antibodies, with a median level of 82 U\/mL.<\/p>\n “Although evidence of natural immunity in unvaccinated healthy U.S. adults up to 20 months after confirmed COVID-19 infection is encouraging, it is unclear how these antibody levels correlate with protection against future SARS-CoV-2 infections, particularly with emerging variants,” the authors write.<\/p>\n One author disclosed financial ties to the pharmaceutical industry.<\/p>\n