Abstract：
This study (1) determined the association of time since initial vaccine regimen, booster dose receipt, and COVID-19 history with antibody titer, as well as change in titer levels over a defined period, and (2) determined risk of COVID-19 associated with low titer levels. This observational study used data from staff participating in the National Football League COVID-19 Monitoring Program. A cohort of staff consented to antibody-focused sub-study, during which detailed longitudinal data were collected. Among all staff in the program who received antibody testing, COVID-19 incidence following antibody testing was determined. Five hundred eighty-six sub-study participants completed initial antibody testing; 80% (469) completed follow-up testing 50-101 days later. Among 389 individuals who were not boosted at initial testing, the odds of titer < 1000 AU/mL (vs. ≥1000 AU/mL) increased 44% (odds ratio [OR] = 1.44, 95% confidence interval [CI]: 1.18-1.75) for every 30 days since final dose. Among 126 participants boosted before initial testing with no COVID-19 history, 125 (99%) had a value > 2500 AU/ml; 86 (96%) of 90 tested at follow-up and did not develop COVID-19 in the interim remained at that value. One thousand fifty-seven fully vaccinated (330 [29%] boosted at antibody test) individuals participating in the monitoring program were followed to determine COVID-19 status. Individuals with titer value < 1000 AU/mL had twice the risk of COVID-19 as those with >2500 AU/mL (HR = 2.02, 95% CI: 1.28-3.18). Antibody levels decrease postvaccination; boosting increases titer values. While antibody level is not a clear proxy for infection immunity, lower titer values are associated with higher COVID-19 incidence, suggesting increased protection from boosters.
摘要：
这项研究(1)确定了自初始疫苗方案以来的时间关联，加强剂量收据，和COVID-19抗体滴度病史，以及滴度水平在定义的时期内的变化，（2）确定与低滴度水平相关的COVID-19风险。这项观察性研究使用了参加国家橄榄球联盟COVID-19监测计划的工作人员的数据。一群工作人员同意以抗体为重点的子研究，在此期间收集了详细的纵向数据。在接受抗体检测的所有工作人员中，确定了抗体测试后的COVID-19发病率。586个子研究参与者完成了初始抗体测试；80％（469）在50-101天后完成了后续测试。在389名在初始测试中没有得到加强的人中，滴度<1000AU/mL的几率(与≥1000AU/mL）自最终剂量以来每30天增加44％（比值比[OR]=1.44，95％置信区间[CI]：1.18-1.75）。在最初测试前没有COVID-19病史的126名参与者中，125(99%)的值>2500AU/ml；在随访中测试的90人中有86人(96%)保持在该值，在此期间没有发展为COVID-19。对参与监测计划的千名57名完全接种疫苗(抗体测试时330名[29%]加强)的个体进行了随访，以确定COVID-19状态。滴度<1000AU/mL的个体患COVID-19的风险是>2500AU/mL的个体的两倍(HR=2.02，95%CI：1.28-3.18)。疫苗接种后抗体水平降低;加强增加效价值。虽然抗体水平不是感染免疫的明确代表，较低的滴度与较高的COVID-19发病率相关，建议加强对助推器的保护。
