eutralizing antibody titer after COVID-19 vaccination in Japanese elderly population - Neutralizing antibody titer after COVID-19 vaccination in Japanese elderly population

The geometric means of the first neutralizing antibody titer (NAT: AU/ml) were 645[49-8745] in OLD group (>= 65: N=119) and 1777 [159-19821] in YOUNG Group (< 65: N=62) respectively. The proportion of subjects (>=1280 AU/ml) were 39/119(32.8%) vs 39/62(62.9%) in the first measurement and 0/16(0.0%) vs 3/16(18.8%) in the second. Negative test results (<50) were 7/119(3.9%) vs (6/62(5.0%) vs 1/61(0.2%)) in the first NAT and (3/16(4.8%) vs 0/13(0.0%) in the second.