The European Medicines Agency warns that young children given GlaxoSmithKline's swine flu shot may get a fever after their second dose.

In a statement issued Friday, the European drug regulator said data from GlaxoSmithKline PLC showed a higher number of children aged six months to 3 years had a fever after their second dose of the Pandemrix vaccine, compared with the first. Kids were also more likely to have side effects like muscle pain, drowsiness, and irritability.

The European regulator recommends children get two doses of swine flu vaccine, though Glaxo says one dose is enough.

Glaxo's vaccine contains an adjuvant, a chemical compound to boost the immune response. It is sold across Europe and Canada.

Another formulation of Glaxo's vaccine, without the adjuvant, is available in the U.S. Vaccines with adjuvants usually cause more side effects. No flu vaccines with adjuvants are licensed in the U.S.

Last month, Glaxo advised health authorities not to use one batch of its Canadian-manufactured swine flu vaccine in case it triggered life-threatening side effects like anaphylactic shock.

In a press briefing on Thursday, the World Health Organization's flu chief Keiji Fukuda said that more than 150 million doses of swine flu vaccine have been distributed in more than 40 countries and that they had not seen any evidence to suggest the vaccines caused worrying side effects.

欧洲药品管理局发出警告说，注射过葛兰素史克公司的猪流感疫苗的幼儿，二次注射之后可能会发热。

在星期五发布的一项声明中，欧洲医药管理部门说，来自葛兰素史克公司的数据表明，与第一次注射相比，数量较多的年龄在6个月到3岁的儿童第二次注射 Pandemnrix 疫苗之后，已出现发热现象。很可能出现副作用，如肌肉酸痛、困倦和过敏。

尽管葛兰素史克公司称注射一次猪流感疫苗就足够了，但欧洲药品管理部门仍建议儿童注射两次。

葛兰素史克公司的疫苗含有一种促进免疫反应的辅药和化学物质。这种疫苗在全欧洲和加拿大销售。

葛兰素史克公司另一种配方的疫苗不含辅助药料，在美国可以买到。含有辅助药料的疫苗通常引起更多的副作用。这种疫苗在美国没有获得许可。

上个月，葛兰史克公司建议卫生机构，如果加拿大生产的一批疫引发威胁生命的象过敏性休克这样的副作用，则不要使用。

在星期二的新闻发布会上，世界卫生组织流感部干事福田敬二说，1.5亿支流感疫苗已发放到40多个国家，还说，他们并没有发现任何表示疫苗引起的让人担忧的副作用的证据。