Results of a longitudinal study confirmed that anti-receptor binding domain (RBD) antibodies conferred by COVID-19 mRNA vaccination decrease over time. In addition, women were more likely to produce antibodies at months 1 and 9 following COVID-19 vaccination compared with men. These findings were published in the International Journal of Infectious Diseases.

Researchers quantified the production of immunoglobulin (Ig) G antibodies among a cohort of 1343 health care workers who received 2-doses of the Pfizer-BioNTech COVID-19 (BNT162b2) vaccine between February and October 2021. The SARS-CoV-2 IgG II Quant assay by Abbott Laboratories (North Chicago, IL) was used to quantify antibodies at 1-, 6- and 9-months after receipt of the vaccine.

The cohort comprised 402 (29.9%) men and 941 (70.1%) women with a median age of 51 (range, 24-68) years. The median concentration of anti-RBD IgG was most increased 1 month after vaccination (1432 binding antibody units [BAU]/mL; range, 0.1-11,360 BAU/mL). At months 6 and 9, the median concentration of anti-RBD IgG antibodies among the participants decreased to 194.3 and 79.3 BAU/mL, respectively. There were significant differences between median anti-RBD IgG concentrations observed at all 3 timepoints (P <.0001), as well as between men and women at months 1 (P =.0373) and 9 (P =.0291). After stratification of participants by age and sex, no significant difference in the mean concentration of antibodies was noted at month 6.


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The researchers noted the need for additional studies to clarify the ways in which patient sex affects the cellular and molecular pathways associated with COVID-19 infection.

According to the researchers, “…these data support the importance of [additional]… vaccine doses, considering also the recent findings that underscore the importance of receiving a third vaccine dose to prevent moderate and severe COVID-19, especially when the Omicron variant is predominant and the effectiveness of [2] doses of [the] vaccine is reduced against this variant.”

Reference

Bordi L, Sberna  G, Piscioneri CN, et al. Longitudinal dynamics of SARS-CoV-2 anti-receptor binding domain IgG antibodies in a wide population of health care workers after BNT162b2 vaccination. Int J Infect Dis. Published online May 31, 2022. doi: 10.1016/j.ijid.2022.05.061