WEDNESDAY, Sept. 15, 2021 (HealthDay News) -- BNT162b2 elicits relatively lower antibody levels to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike receptor binding domain (RBD) than mRNA-1273, and lower antibody levels are observed with BNT162b2 in older versus younger adults, according to a research letter published online Sept. 2 in JAMA Network Open.
Nathan E. Richards, M.D., from the University of Virginia in Charlottesville, and colleagues examined whether there are differences in antibody levels elicited by the BNT162b2 and mRNA-1273 vaccines. Data were included for 79 participants who received BNT162b2 and 88 who received mRNA-1273; all individuals received two doses of vaccine and had a blood sample drawn at seven to 31 days after the second dose (postboost).
The researchers found that the levels of immunoglobulin G (IgG) to the SARS-CoV-2 spike RBD were lower for those receiving BNT162b2 versus mRNA-1273 at both the preboost blood draw (5.9 versus 19.1 µg/mL) and postboost blood draw (45.9 versus 68.5 µg/mL). Recipients aged 50 years and older who received BNT162b2 had preboost IgG levels that were lower than those of recipients aged younger than 50 years and compared with those aged 50 years or older who received mRNA-1273 (2.1 µg/mL versus 10.2 and 14.7 µg/mL, respectively). The corresponding postboost levels were 31.3 µg/mL versus 59.0 and 71.8 µg/mL.
"BNT162b2 elicited relatively lower antibody levels in older adults versus younger adults, which is consistent with emerging reports," the authors write. "Additional studies are warranted to determine whether binding antibodies to SARS-CoV-2 can be used to predict clinical protection against COVID-19."
Two authors disclosed financial ties to Thermo-Fisher/Phadia.
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