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Covid-19: Antibody levels fall after second Pfizer dose, but protection against severe disease remains, studies indicate

BMJ 2021; 375 doi: https://doi.org/10.1136/bmj.n2481 (Published 11 October 2021) Cite this as: BMJ 2021;375:n2481

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  1. Elisabeth Mahase
  1. The BMJ

Six months after the second dose of the Pfizer-BioNTech covid-19 vaccine, antibody concentrations in healthcare workers had decreased substantially, especially among older men and immunosuppressed people, a study has found.1

The Israeli researchers carried out a six month longitudinal prospective study that involved monthly antibody testing of around 4000 vaccinated healthcare workers. At six months the mixed-model analysis showed decreases in antibody concentrations of 38% for IgG antibodies and 42% for neutralising antibodies among those aged 65 years or older, when compared with participants aged 18-45. Decreases of 37% (IgG) and 46% (neutralising) were also seen in men 65 years of age or older when compared with women in the same age group.

The study, published in the New England Journal of Medicine …

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