COVID-19 antibody levels are highest in women after vaccination

In an ongoing study from the Texas Biomedical Research Institute, experts have found that after vaccination, COVID-19 antibody levels vary by age and sex. The researchers also found that antibody levels drop significantly within six months across all individuals.

The study participants were tested over the course of six months after receiving the Pfizer-BioNTech vaccine. The tests revealed that individuals under the age of 65 had more than twice the level of SARS-COV-2 antibodies than individuals 65 years and older. In addition, women had higher antibody levels than men, especially women under the age of 65. 

The experts report that by the sixth month, antibody levels had decreased by more than 50 percent from peak levels for all study participants. 

“While we see how well vaccines have helped keep people out of the hospital and prevent life-threatening disease, antibody levels are quickly declining in all persons regardless of age and sex,” said Dr. Brandon Michael Henry, a postdoctoral researcher at Texas Biomed who co-led the study. He emphasized that the decline in antibody level does not mean that the vaccines are not effective

The study was focused on 787 healthcare workers in Verona, Italy who received two doses of the Pfizer-BioNTech vaccine. The individuals ranged in age from 21 to 75. 

The researchers theorize that the significant sex differences are linked to hormones. They noted that testosterone naturally suppresses the immune system, while estrogen is known to amplify immune responses. 

Furthermore, some genes that code for certain immune proteins are on the X chromosome. Women have two X chromosomes, which could help increase immune activity.

“Normally, only one X chromosome is active and the other is mostly deactivated, but there is evidence that immune-related genes stay active on that redundant chromosome and help boost immune responses in women,” said Dr. Henry.

“We have observed throughout the pandemic more older people and men suffer the worst consequences of COVID-19. These studies point to weaker immune responses against SARS-CoV-2 as a contributing factor to this phenomenon.”

“Our study provides additional evidence that booster shots for all adults will be important to keep antibody levels up so we can continue to mount an effective immune response against COVID-19 infection and prevent COVID-19 fatalities.”

The study is published in the Journal of Medical Biochemistry.

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By Chrissy Sexton, Earth.com Staff Writer