Six months after a second dose of a Pfizer COVID-19 vaccine, men had substantially lower levels of neutralizing antibodies than women in a study published Oct. 6 in The New England Journal of Medicine.
The study included 4,868 healthcare workers vaccinated with two doses of a Pfizer vaccine in Israel. It took place between Dec. 19 and July 9.
The researchers found that antibody levels decreased rapidly in both sexes for the first three months following the second dose, with a relatively slow decrease after. After six months, women generally had higher levels of antibodies.
People ages 18 to 45 also had higher antibody levels than people over the age of 65 after the second dose.
A study published in November that included 308 healthcare workers in France who tested positive for COVID-19 also found that antibody levels declined faster in males than in females, The Washington Post reported.
Find the full study results here.