The excess risk of developing Guillain-Barré syndrome associated with receipt of the pandemic influenza A(H1N1) vaccine is less than 1 case per 1 million vaccinations – a rate comparable to that seen for some trivalent seasonal influenza vaccines.

Preliminary results released in the June 2 issue of the U.S. Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report found 326 confirmed new cases of the neurological disorder from Oct. 1, 2009 – May 10, 2010 (MMWR 2010; 59:1-5). Of these patients, 27 reported having had the pandemic flu vaccine within 42 days of the onset of GBS – the time period considered plausible for any biologic link between the two. Most of these patients reported an antecedent illness typically related to GBS onset (gastrointestinal illness or respiratory infection).

“Notably, this high proportion of antecedent illnesses associated with GBS suggests that a number of the GBS illnesses observed after vaccination might be attributable to other antecedent illnesses,” wrote C. Prothro of the California Emerging Infections Program, Oakland, and co-authors. “Historically, 40%-70% of GBS patients report experiencing antecedent infectious illness.”

If the preliminary analysis is confirmed – which the CDC expects to happen by this fall – then the attributable rate of GBS would be 0.71 per 100,000 person-years, corresponding to an excess GBS rate of 0.8 cases per 1 million vaccinations, the report said.

Although the report deemed the risk of vaccination-related GBS to be low with pandemic flu vaccine, it did recommend caution for patients with GBS who might consider vaccination.

“Persons with a history of GBS should discuss potential risks and benefits with their health-care providers before receiving any influenza vaccine,” K.R. Copeland of the National Opinion Research Center, Chicago, and co-authors wrote in an accompanying editorial note. “However, risk assessment should take into account that influenza and influenza-like illnesses are associated with significant morbidity and mortality, including a hospitalization rate of 222 per 1 million population and a death rate of 9.7 per 1 million population for H1N1-associated illnesses, as well as possible increased risk for GBS.”

Of the 326 confirmed GBS cases, 27 had documentation proving pandemic flu vaccination within the 42-day window; vaccination status could not be determined in 25, and 274 did not take the vaccine.

Sixteen of the 27 (59%) who received the vaccine experienced antecedent symptoms before their GBS diagnosis. The program found no clustering of GBS between vaccination and illness onset.

Among the 27 with the disorder who were vaccinated, 4 (15%) required ventilator support, and 1 was hospitalized for 30 days. Among the 274 GBS patients who were not vaccinated, 37 (14%) required ventilator support, and 34 (12%) were hospitalized for 30 days after illness onset. Eight GBS patients died (2%); none of them had received the pandemic flu vaccine.

The CDC study used data gathered by its own Emerging Infections Program. The program has collaborated with the CDC, state health centers, and academic centers in 10 states to rapidly identify new GBS cases following pandemic flu vaccination. The surveillance areas included Connecticut, Maryland, Minnesota, New Mexico, Tennessee, and New York state (excluding Manhattan), and selected metropolitan counties in California, Colorado, Georgia, and Oregon. GBS incidence was calculated and compared for the vaccinated and unvaccinated populations.

No financial conflicts were reported in the study.

Copyright (c) 2009 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

大流行性甲型流感(H1N1)疫苗接种者发生吉兰-巴雷综合征(GBS)的额外风险低于1例/100万接种者，与一些三价季节性流感疫苗相当。

 

美国疾病预防控制中心(CDC)的《发病率与死亡率周报》6月2日发布的初步结果显示，2009年10月1日~2010年5月10日期间，新确诊为该神经疾病的病例为326例(MMWR 2010; 59:1-5)。在这些患者中，27例在GBS发病的42天内曾接种过大流行性流感疫苗，这被认为是两者之间发生生物学关联的一个时间段。大部分患者出现与GBS发病相关的典型前驱疾病(胃肠道疾病或呼吸道感染)。

 

奥克兰加利福尼亚新发感染病计划的C. Prothro博士及其同事写道：“值得注意的是，这一较高的GBS相关前驱疾病发病率表明，一些在接种后观察到的GBS疾病或可归因于其他前驱疾病。从既往数据来看，40%~70%的GBS患者出现前驱感染病。”

 

该报告称，CDC预计在今年秋季对该初步分析进行证实，如果得以证实，那么GBS归因发病率将为0.71例/ 100,000人年，相当于GBS额外发生率为0.8例/100万接种者。

 

尽管该报告认为，与大流行性流感疫苗接种相关的GBS风险较低，但仍建议欲接种的GBS患者应慎重考虑。

 

芝加哥国家民意研究中心的K.R. Copeland及其同事在随刊编者按中写道：“具有GBS病史的个体应在接种任何流感疫苗之前与其医生就潜在风险和效益进行商讨。然而，进行风险评估时，应考虑流感和流感样疾病与高发病率及死亡率之间的联系(如H1N1相关疾病所致住院率为222例/100万人、死亡率为9.7例/100万人)，以及GBS风险的增加。”

 

在326例确诊GBS的病例中，27例的病历记录显示大流行性流感疫苗接种的时间是在42天窗口期内；25例的接种情况未能明确，274例未接种该疫苗。

 

在接种疫苗的27例中，有16例(59%)在诊断GBS前出现前驱症状。该项目在接种后至发病前这段时间内未发现GBS聚集现象。

 

在27例接种的GBS患者中，4例(15%)需要呼吸机支持，1例住院30天。 在274例未接种的GBS患者中，37例(14%)需要呼吸机支持，34例(12%)在发病后住院了30天，8例(2%)死亡。

 

该CDC研究采用的是其新发感染病计划所收集的数据。该计划与CDC、州立卫生中心及10个州的学术中心进行合作，目的在于快速发现接种大流行性流感疫苗后新发的GBS病例。 监测区域包括康涅狄格州、马里兰州、明尼苏达州，新墨西哥州、田纳西州和纽约州(排除曼哈顿)以及加利福尼亚州、科罗拉多州、佐治亚州和俄勒冈州的部分大都会郊区。计算接种人群和未接种人群的GBS发生率，并进行比较。

 

该研究无任何经济利益冲突报告。

 

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