A Japanese pre-print study analyzed antibody titers of 365 healthcare workers 3 and 6 months after receiving the second dose of the Pfizer vaccine. Their results showed that when adjusting for age, smoking was associated with lower titers, and a significant association is found with the female gender with a 31% drop compared to 25% in men. Older individuals in their 60-70s had nearly half of the antibody titers measured in people in their 20s.
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