A cluster of nonspecific adverse events in a military reserve unit following pandemic influenza A (H1N1) 2009 vaccination—Possible stimulated reporting?

Background On February 20, 2010, a 23 year old male Army Reservist (index case) with symptom onset 4h after receiving inactivated monovalent pandemic 2009 (H1N1) vaccine (MIV) was hospitalized with possible Guillain-Barré syndrome (GBS). Within 1–2 days, 13 reservists from the same unit presented to the emergency department and 14 filed Vaccine Adverse Event Reporting System (VAERS) reports of nonspecific symptoms following MIV. Objectives To describe the spectrum of adverse events (AE) among reservists in the unit after MIV and to identify factors contributing to this cluster of reports. Methods We reviewed the reservists’ VAERS reports and hospital records for demographics, influenza vaccination status, diagnostic results and outcome. All VAERS reports after vaccination from the same MIV lot were also screened. We conducted a survey of unit reservists to identify contributing factors for this cluster. Results The presumptive diagnosis of GBS in the index case was not confirmed. All other reservists demonstrated normal exam findings and laboratory investigations. VAERS reports following vaccination from the same MIV lot revealed no consistent pattern. Our survey of factors contributing to the cluster was returned by 55 reservists (response rate 28%). AEs following MIV were significantly more often reported by female and black reservists. There was a tendency for concern about the safety of the 2010–2011 seasonal influenza vaccine to be higher for reservists that reported an AE to MIV (p =0.13) or that sought medical attention for their symptoms (p =0.08). Conclusions This cluster represents possible stimulated reporting following receipt of inactivated pandemic 2009 (H1N1) vaccine among service personnel.

背景 2010年2月20日，一名23岁的男性陆军预备役军人（指示病例）在接种2009年甲型H1N1流感单价灭活疫苗（MIV）4小时后出现症状，因可能患有吉兰 - 巴雷综合征（GBS）而住院。在1 - 2天内，同一部队的13名预备役军人前往急诊科就诊，14人向疫苗不良事件报告系统（VAERS）提交了接种MIV后出现非特异性症状的报告。 目的 描述该部队预备役军人接种MIV后的不良事件（AE）谱，并确定导致这一系列报告的因素。 方法 我们查阅了预备役军人的VAERS报告和医院记录，以了解人口统计学信息、流感疫苗接种情况、诊断结果和预后。还对同一批MIV接种后的所有VAERS报告进行了筛选。我们对该部队的预备役军人进行了一项调查，以确定导致这一聚集性事件的因素。 结果 指示病例中GBS的推定诊断未得到证实。所有其他预备役军人的检查结果和实验室检查均正常。同一批MIV接种后的VAERS报告未显示出一致的模式。我们对导致聚集性事件的因素进行的调查有55名预备役军人回复（回复率28%）。女性和黑人预备役军人报告接种MIV后出现不良事件的频率明显更高。对2010 - 2011年季节性流感疫苗安全性表示担忧的情况在接种MIV后报告有不良事件的预备役军人（p = 0.13）或因症状就医的预备役军人（p = 0.08）中更为常见。 结论 这一聚集性事件代表了军人在接种2009年甲型H1N1流感灭活疫苗后可能出现的受激发的报告情况。