Swine flu has become the world's first official pandemic in 41 years after the World Health Organisation raised the alert level on the H1N1 virus from phase 5 to 6, the highest on the scale.

    The decision was made after a meeting of experts in Geneva today and comes as infections have climbed in Europe, the US, Australia, South America and elsewhere. The WHO chief, Dr Margaret Chan, yesterday examined data from eight countries with large numbers of swine flu cases.

    "The world is moving into the early days of its first influenza pandemic in the 21st century," Chan told reporters tonight, advising that countries should prepare for a second wave of cases. "The [swine flu] virus is now unstoppable."

    Raising the alert level reflects that the virus is more widespread, but not necessarily more dangerous – although there are fears that infections could overwhelm hospitals and health authorities, especially in poorer countries.

    Another 25 cases of swine flu have been confirmed in England and 26 more in Scotland, taking the UK total to 848.

    Speaking to health service managers in Liverpool at a conference of NHS trusts, the UK's new health secretary, Andy Burnham, said: "It's not a cause for alarm. It doesn't change our plans."

    Swine flu originated in Mexico in April and has spread to 74 countries, infecting more than 27,700 people and killing 140.

    Most cases have been mild, although employers are being warned to prepare for absences through illness.

    The WHO said pharmaceutical companies should start making swine flu vaccine. One manufacturer, GlaxoSmithKline PLC, said it could start large-scale production by July but large quantities would not be available for several months.

    Despite the WHO's hopes, the announcement of a pandemic will almost certainly spark panic in some countries. Fear has already gripped Argentina, where thousands of people worried about swine flu flooded into hospitals this week, bringing to near-collapse the emergency health services in the capital, Buenos Aires.

    "People might imagine a virus is now going to rush in and kill everyone," said John Oxford, a professor of virology at St Bart's and Royal London hospital. "That's not going to happen."

    There are 337 cases in Scotland and health officials in Edinburgh said 30% of them were in young adults aged 15-24.

    The Scottish health secretary, Nicola Sturgeon, said public health tactics had changed after it emerged the virus was spreading uncontrolled.

    Sturgeon told the Scottish parliament this morning that hospitalisation rates were similar to those in the US. She indicated that attempts to contain the virus had failed and the strategy would be to limit its spread. Doctors in the most-affected areas – Glasgow, Dunoon and Paisley – would be allowed to make a swine flu diagnosis in their surgeries rather than wait for specialist or laboratory tests.

    England's chief medical officer, Sir Liam Donaldson, said health officials were expecting to see more and more cases this autumn and winter with the return of the traditional flu season, and the virus might yet change and become more severe.

    There were "very strong" plans in place to deal with the flu and so far the government's approach, including closing schools where necessary, appeared to have worked well, he said.

    At the NHS Confederation conference, senior health service managers held an early-morning session to refine their emergency plans. Contingency arrangements are being drawn up to allow for hospitals and health centres to continue operating when as many as 40% of staff are off sick.

    Steve Barnett, the chief executive of the NHS Confederation, which represents most health and ambulance trusts, said: "The confirmation of a level 6 global pandemic reinforces the need for the NHS to ensure all the flu plans already in place at local level are as comprehensive as possible and thoroughly tested.

    "We need to avoid complacency in dealing with a virus that is an unknown and seems to be spreading quickly."

    The last such pandemic was the Hong Kong flu of 1968 that killed about a million people. Ordinary flu kills about 250,000 to 500,000 people each year.

    世界卫生组织宣布将甲型H1N1流感病毒的警戒级别由5级提升至最高级别6级，至此，猪流感已成为41年来世界上第一个正式的全球大流行病。

    鉴于欧洲、美国、澳大利亚、南美洲及世界其他地方的感染病例不断增加，今天在日内瓦召开的专家会议宣布了这一决定。世卫总干事陈冯富珍（Margaret Chan）博士昨天审查来自八个猪流感病例最多的国家的统计数据。

    "世界正进入二十一世纪第一场全球流感大流行的初期阶段，"陈总干事今晚告诉记者，她建议各国应该做好准备应对流感第二波疫情的出现。"目前这[猪流感]病毒的流行是无法阻止了。"

    提高警戒级别表明病毒传播愈加广泛，但并不一定意味着病毒本身愈加危险--尽管有些人担心病毒感染的事态会发展到令医院和卫生主管部门无法应付，尤其是在较贫穷国家。

    英格兰又有25个猪流感确认病例，苏格兰另有26个，英国的流感确认病例总数上升为848例。

    在利物浦召开的英国全民医疗保健系统信托组织（NHS trusts）会议上，英国新任卫生大臣安迪·伯纳姆（Andy Burnham）对与会的公共医疗卫生服务主管们说："不必惊慌。我们的计划不变。"

    猪流感于今年4月在墨西哥爆发，现已蔓延到74个国家，感染人数超过27700人，死亡人数达140人。

    虽然已预先告知雇主做好应对员工因病缺勤的准备，但目前来看，大多数病例的病情温和。

    世卫组织建议制药公司应该开始抓紧生产猪流感疫苗。英国制药商葛兰素史克公司（GlaxoSmithKline PLC）宣布，公司7月份之前可以开始大规模生产猪流感疫苗，但几个月内无法供应大量疫苗。

    尽管世卫组织希望大家保持镇定，宣布全球大流行肯定会在一些国家引发恐慌。阿根廷已经笼罩在恐惧之中，本周数以千计担心猪流感的人涌入各家医院，导致首都布宜诺斯艾利斯的紧急医疗服务接近崩溃。

    "人们可能以为这种病毒现正在迅速蔓延而导致每一个人病亡，"圣巴特及皇家伦敦医院的病毒学教授约翰·奥克斯佛（John Oxford）说，"这绝不会发生。"

    在苏格兰有337个猪流感病例。爱丁堡的卫生官员指出，其中30%的感染者是年龄在15岁至24岁的年轻人。

    苏格兰卫生部长尼古拉·斯特金（Nicola Sturgeon）表示，自从猪流感病毒的蔓延失控之后，公众卫生部门的应对策略已有所改变。

    斯特金今天上午在苏格兰议会上报告，苏格兰猪流感病例的住院率和美国大致相同。她表示，控制病毒的努力已经失败，现在的策略是限制病毒传播。猪流感病毒感染最严重的地区--格拉斯哥（Glasgow）、丹农（Dunoon）及佩斯利（Paisley）的医生将被允许在各自的诊所现场进行猪流感诊断，而不需等待专家或化验。

    英格兰首席医务官利亚姆·唐纳森爵士（Sir Liam Donaldson）表示，卫生官员们预期，随着传统流感季节的到来，今年秋冬两猪流感病例会越来越多，而且这种病毒可能还会变化，变得更加严重。

    他说，政府已部署了"非常有力"的计划来应对猪流感，迄今为止，政府的应对措施，包括必要时关闭学校，看来效果良好。

    在英国国家卫生服务联盟（NHS Confederation）会议上，公共医疗卫生服务的高级主管们举行了一次晨会，旨在优化他们的应急计划。正在拟订的应变计划为医院和保健中心在多达40%的工作人员因病缺勤的情况下继续运作提供了适当安排。

    代表大多数卫生及救护信托组织的英国国家卫生服务联盟的行政长官史蒂夫·巴内特（Steve Barnett）说："全球大流行病6级警戒级别的确认，更增强了国家卫生服务体系（NHS）的重要性，以确保所有已制定的在地方级流感应对计划尽可能全面、尽可能经过彻底验证。

    "在应对这个似乎正迅速蔓延而又未知的病毒方面，我们必须避免有自满情绪。"

    上一次发生的全球大流行病是1968年的香港流感，那次约有100万人死亡。普通流每年造成25万至50万人的死亡。