H1N1相关侵袭性肺炎增多

Investigators at the U.S. Centers for Disease Control and Prevention are seeing a “worrisome spike” in serious bacterial pneumonia associated with pandemic influenza A(H1N1) virus, Dr. Anne Schuchat said a press briefing on Nov. 25.

In the Denver metropolitan area, for example, there were 58 reported cases of invasive pneumococcal infections during the month of October. Over the last 5 years, there have been an average of only 20 cases each October.

Invasive bacterial pneumonia is normally seen in individuals older than age 65. But about two-thirds of the patients in Denver are between the ages of 20 and 59 years, Dr. Schuchat said. The majority had underlying risk factors in addition to H1N1 influenza.

“People at risk for invasive pneumococcal [infection] include adults with chronic health conditions like diabetes, asthma, emphysema, or chronic lung disease, chronic heart disease, chronic kidney or liver disease, cancer and other immunosuppressive conditions like HIV,” Dr. Schuchat said. “So a lot of adults are at higher risk for pneumococcal complications.”

Studies show that only one-quarter of patients in these high-risk groups has received the highly effective and available pneumococcal vaccine. Adults typically require only one dose of the vaccine for lifetime protection.

In a person infected with influenza, an easing of symptoms followed by a sudden worsening is a key warning sign of a secondary bacterial infection. “We can see that in children or in adults,” Dr. Schuchat said. “And it doesn’t necessarily always mean bacterial pneumonia, but it very much can mean that.”

Other H1N1 influenza news discussed during the press briefing included confirmation that a physician in the state of West Virginia appears to have come down with laboratory-verified H1N1 influenza twice over a period of 3 or 4 months. This is uncommon but not impossible, Dr. Schuchat said, and this case does not bear on the efficacy of the H1N1 virus vaccine, which is highly – but not 100% – effective.

To date 61.2 million doses of the vaccine have been made available in the United States, with an additional 7 million doses since Nov. 20. “We are expecting vaccination efforts to really step up as we come into December in concert with these improved supplies,” Dr. Schuchat said.

The CDC continues to investigate adverse events associated with the vaccine. So far 94% of such reports relate to mild reactions such as soreness, tenderness, or injection-site pain. Anaphylaxis is not occurring more frequently than expected.

There have been 10 reports of possible cases of Guillain-Barré syndrome (GBS) associated with the vaccine, but not all of those have been confirmed. GBS is of particular concern because of a large number of cases associated with the 1976 swine flu vaccine. Dr. Schuchat said that 10 cases is a small number, given the large number of vaccine doses that have been administered.

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Anne Schuchat博士在11月25日召开的一次新闻发布会上说，美国疾病预防控制中心(CDC)的研究人员发现，大流行性甲型流感 (H1N1) 病毒相关重度细菌性肺炎“令人担忧地出现了大幅上升”。

例如，10月份丹佛市区报告发现58例侵袭性肺炎球菌感染患者。在过去5年里，每年10月份仅平均20例。

侵袭性细菌性肺炎常发生于年龄>65岁的人群。但Schuchat说，在丹佛，约有2/3的患者年龄为20~59岁。大多数患者具有除H1N1流感之外的潜在危险因素。

Schuchat博士说：“具有侵袭性肺炎球菌感染危险因素的人群包括患有慢性疾病的成人，如糖尿病、哮喘、肺气肿，或慢性肺、心、肾、肝脏疾病，或肿瘤及其他免疫抑制性疾病，如HIV感染。所以，很多成人发生肺炎并发症的风险较高。”

研究显示，上述高危人群中仅1/4的患者接种过现有高效肺炎球菌疫苗。成年人通常仅需接种1剂该疫苗即可获得终身保护。

对于流感感染者，症状缓解后病情突然加重是继发细菌感染的重要警示标志。Schuchat博士说：“我们可以在儿童和成人中发现这种现象，虽然这并非总意味着细菌性肺炎，但大多数是。”

在此次新闻发布会上讨论的有关H1N1流感的其他新闻还包括：西弗吉尼亚州一位内科医生在3或4个月内两次感染经实验室证实的H1N1流感。Schuchat博士说，这很少见但并非不可能；该情况对H1N1病毒疫苗的效力并无影响，它虽然高效，但并非百分百有效。

直至今日，美国共生产了6,120万剂H1N1病毒疫苗，而11月20日之后就有700万剂。Schuchat博士说：“眼看进入12月份，我们期望免疫接种的步伐真正随着疫苗供应的增加而加快。”

CDC在继续调查与该疫苗相关的不良事件。迄今为止，94%的不良事件报告均为轻度反应，如酸痛、压痛或注射部位疼痛。过敏反应的发生率并不像预期的那么高。

至今，已报告发生10例与该疫苗相关的吉兰-巴雷综合征(GBS)，但并非所有患者均被确诊。由于大量GBS的发生与1976年猪流感的疫苗相关，所以其颇受关注。Schuchat博士说，鉴于已注射疫苗的总剂量，10例只是个小数目。

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